FreeBSD kernel kern code
sched_ule.c
Go to the documentation of this file.
1 /*-
2  * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  * notice unmodified, this list of conditions, and the following
10  * disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  * notice, this list of conditions and the following disclaimer in the
13  * documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 /*
28  * This file implements the ULE scheduler. ULE supports independent CPU
29  * run queues and fine grain locking. It has superior interactive
30  * performance under load even on uni-processor systems.
31  *
32  * etymology:
33  * ULE is the last three letters in schedule. It owes its name to a
34  * generic user created for a scheduling system by Paul Mikesell at
35  * Isilon Systems and a general lack of creativity on the part of the author.
36  */
37 
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD: head/sys/kern/sched_ule.c 263324 2014-03-19 00:38:27Z attilio $");
40 
41 #include "opt_hwpmc_hooks.h"
42 #include "opt_sched.h"
43 
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/kdb.h>
47 #include <sys/kernel.h>
48 #include <sys/ktr.h>
49 #include <sys/limits.h>
50 #include <sys/lock.h>
51 #include <sys/mutex.h>
52 #include <sys/proc.h>
53 #include <sys/resource.h>
54 #include <sys/resourcevar.h>
55 #include <sys/sched.h>
56 #include <sys/sdt.h>
57 #include <sys/smp.h>
58 #include <sys/sx.h>
59 #include <sys/sysctl.h>
60 #include <sys/sysproto.h>
61 #include <sys/turnstile.h>
62 #include <sys/umtx.h>
63 #include <sys/vmmeter.h>
64 #include <sys/cpuset.h>
65 #include <sys/sbuf.h>
66 
67 #ifdef HWPMC_HOOKS
68 #include <sys/pmckern.h>
69 #endif
70 
71 #ifdef KDTRACE_HOOKS
72 #include <sys/dtrace_bsd.h>
73 int dtrace_vtime_active;
74 dtrace_vtime_switch_func_t dtrace_vtime_switch_func;
75 #endif
76 
77 #include <machine/cpu.h>
78 #include <machine/smp.h>
79 
80 #define KTR_ULE 0
81 
82 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX)))
83 #define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU)))
84 #define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load"))
85 
86 /*
87  * Thread scheduler specific section. All fields are protected
88  * by the thread lock.
89  */
90 struct td_sched {
91  struct runq *ts_runq; /* Run-queue we're queued on. */
92  short ts_flags; /* TSF_* flags. */
93  u_char ts_cpu; /* CPU that we have affinity for. */
94  int ts_rltick; /* Real last tick, for affinity. */
95  int ts_slice; /* Ticks of slice remaining. */
96  u_int ts_slptime; /* Number of ticks we vol. slept */
97  u_int ts_runtime; /* Number of ticks we were running */
98  int ts_ltick; /* Last tick that we were running on */
99  int ts_ftick; /* First tick that we were running on */
100  int ts_ticks; /* Tick count */
101 #ifdef KTR
102  char ts_name[TS_NAME_LEN];
103 #endif
104 };
105 /* flags kept in ts_flags */
106 #define TSF_BOUND 0x0001 /* Thread can not migrate. */
107 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */
108 
109 static struct td_sched td_sched0;
110 
111 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0)
112 #define THREAD_CAN_SCHED(td, cpu) \
113  CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask)
114 
115 /*
116  * Priority ranges used for interactive and non-interactive timeshare
117  * threads. The timeshare priorities are split up into four ranges.
118  * The first range handles interactive threads. The last three ranges
119  * (NHALF, x, and NHALF) handle non-interactive threads with the outer
120  * ranges supporting nice values.
121  */
122 #define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1)
123 #define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2)
124 #define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE)
125 
126 #define PRI_MIN_INTERACT PRI_MIN_TIMESHARE
127 #define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1)
128 #define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE)
129 #define PRI_MAX_BATCH PRI_MAX_TIMESHARE
130 
131 /*
132  * Cpu percentage computation macros and defines.
133  *
134  * SCHED_TICK_SECS: Number of seconds to average the cpu usage across.
135  * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across.
136  * SCHED_TICK_MAX: Maximum number of ticks before scaling back.
137  * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results.
138  * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count.
139  * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks.
140  */
141 #define SCHED_TICK_SECS 10
142 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS)
143 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz)
144 #define SCHED_TICK_SHIFT 10
145 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT)
146 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz))
147 
148 /*
149  * These macros determine priorities for non-interactive threads. They are
150  * assigned a priority based on their recent cpu utilization as expressed
151  * by the ratio of ticks to the tick total. NHALF priorities at the start
152  * and end of the MIN to MAX timeshare range are only reachable with negative
153  * or positive nice respectively.
154  *
155  * PRI_RANGE: Priority range for utilization dependent priorities.
156  * PRI_NRESV: Number of nice values.
157  * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total.
158  * PRI_NICE: Determines the part of the priority inherited from nice.
159  */
160 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN)
161 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2)
162 #define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF)
163 #define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF)
164 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1)
165 #define SCHED_PRI_TICKS(ts) \
166  (SCHED_TICK_HZ((ts)) / \
167  (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE))
168 #define SCHED_PRI_NICE(nice) (nice)
169 
170 /*
171  * These determine the interactivity of a process. Interactivity differs from
172  * cpu utilization in that it expresses the voluntary time slept vs time ran
173  * while cpu utilization includes all time not running. This more accurately
174  * models the intent of the thread.
175  *
176  * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate
177  * before throttling back.
178  * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time.
179  * INTERACT_MAX: Maximum interactivity value. Smaller is better.
180  * INTERACT_THRESH: Threshold for placement on the current runq.
181  */
182 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT)
183 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT)
184 #define SCHED_INTERACT_MAX (100)
185 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2)
186 #define SCHED_INTERACT_THRESH (30)
187 
188 /*
189  * These parameters determine the slice behavior for batch work.
190  */
191 #define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */
192 #define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */
193 
194 /* Flags kept in td_flags. */
195 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */
196 
197 /*
198  * tickincr: Converts a stathz tick into a hz domain scaled by
199  * the shift factor. Without the shift the error rate
200  * due to rounding would be unacceptably high.
201  * realstathz: stathz is sometimes 0 and run off of hz.
202  * sched_slice: Runtime of each thread before rescheduling.
203  * preempt_thresh: Priority threshold for preemption and remote IPIs.
204  */
206 static int tickincr = 8 << SCHED_TICK_SHIFT;
207 static int realstathz = 127; /* reset during boot. */
208 static int sched_slice = 10; /* reset during boot. */
209 static int sched_slice_min = 1; /* reset during boot. */
210 #ifdef PREEMPTION
211 #ifdef FULL_PREEMPTION
212 static int preempt_thresh = PRI_MAX_IDLE;
213 #else
214 static int preempt_thresh = PRI_MIN_KERN;
215 #endif
216 #else
217 static int preempt_thresh = 0;
218 #endif
220 static int sched_idlespins = 10000;
221 static int sched_idlespinthresh = -1;
222 
223 /*
224  * tdq - per processor runqs and statistics. All fields are protected by the
225  * tdq_lock. The load and lowpri may be accessed without to avoid excess
226  * locking in sched_pickcpu();
227  */
228 struct tdq {
229  /*
230  * Ordered to improve efficiency of cpu_search() and switch().
231  * tdq_lock is padded to avoid false sharing with tdq_load and
232  * tdq_cpu_idle.
233  */
234  struct mtx_padalign tdq_lock; /* run queue lock. */
235  struct cpu_group *tdq_cg; /* Pointer to cpu topology. */
236  volatile int tdq_load; /* Aggregate load. */
237  volatile int tdq_cpu_idle; /* cpu_idle() is active. */
238  int tdq_sysload; /* For loadavg, !ITHD load. */
239  int tdq_transferable; /* Transferable thread count. */
240  short tdq_switchcnt; /* Switches this tick. */
241  short tdq_oldswitchcnt; /* Switches last tick. */
242  u_char tdq_lowpri; /* Lowest priority thread. */
243  u_char tdq_ipipending; /* IPI pending. */
244  u_char tdq_idx; /* Current insert index. */
245  u_char tdq_ridx; /* Current removal index. */
246  struct runq tdq_realtime; /* real-time run queue. */
247  struct runq tdq_timeshare; /* timeshare run queue. */
248  struct runq tdq_idle; /* Queue of IDLE threads. */
250 #ifdef KTR
251  char tdq_loadname[TDQ_LOADNAME_LEN];
252 #endif
253 } __aligned(64);
254 
255 /* Idle thread states and config. */
256 #define TDQ_RUNNING 1
257 #define TDQ_IDLE 2
258 
259 #ifdef SMP
260 struct cpu_group *cpu_top; /* CPU topology */
262 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000))
263 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity))
265 /*
266  * Run-time tunables.
267  */
268 static int rebalance = 1;
269 static int balance_interval = 128; /* Default set in sched_initticks(). */
270 static int affinity;
271 static int steal_idle = 1;
272 static int steal_thresh = 2;
274 /*
275  * One thread queue per processor.
276  */
277 static struct tdq tdq_cpu[MAXCPU];
278 static struct tdq *balance_tdq;
279 static int balance_ticks;
280 static DPCPU_DEFINE(uint32_t, randomval);
281 
282 #define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)])
283 #define TDQ_CPU(x) (&tdq_cpu[(x)])
284 #define TDQ_ID(x) ((int)((x) - tdq_cpu))
285 #else /* !SMP */
286 static struct tdq tdq_cpu;
287 
288 #define TDQ_ID(x) (0)
289 #define TDQ_SELF() (&tdq_cpu)
290 #define TDQ_CPU(x) (&tdq_cpu)
291 #endif
292 
293 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type))
294 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t)))
295 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f))
296 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t)))
297 #define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock))
298 
299 static void sched_priority(struct thread *);
300 static void sched_thread_priority(struct thread *, u_char);
301 static int sched_interact_score(struct thread *);
302 static void sched_interact_update(struct thread *);
303 static void sched_interact_fork(struct thread *);
304 static void sched_pctcpu_update(struct td_sched *, int);
305 
306 /* Operations on per processor queues */
307 static struct thread *tdq_choose(struct tdq *);
308 static void tdq_setup(struct tdq *);
309 static void tdq_load_add(struct tdq *, struct thread *);
310 static void tdq_load_rem(struct tdq *, struct thread *);
311 static __inline void tdq_runq_add(struct tdq *, struct thread *, int);
312 static __inline void tdq_runq_rem(struct tdq *, struct thread *);
313 static inline int sched_shouldpreempt(int, int, int);
314 void tdq_print(int cpu);
315 static void runq_print(struct runq *rq);
316 static void tdq_add(struct tdq *, struct thread *, int);
317 #ifdef SMP
318 static int tdq_move(struct tdq *, struct tdq *);
319 static int tdq_idled(struct tdq *);
320 static void tdq_notify(struct tdq *, struct thread *);
321 static struct thread *tdq_steal(struct tdq *, int);
322 static struct thread *runq_steal(struct runq *, int);
323 static int sched_pickcpu(struct thread *, int);
324 static void sched_balance(void);
325 static int sched_balance_pair(struct tdq *, struct tdq *);
326 static inline struct tdq *sched_setcpu(struct thread *, int, int);
327 static inline void thread_unblock_switch(struct thread *, struct mtx *);
328 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int);
329 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS);
330 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb,
331  struct cpu_group *cg, int indent);
332 #endif
333 
334 static void sched_setup(void *dummy);
335 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL);
336 
337 static void sched_initticks(void *dummy);
338 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks,
339  NULL);
340 
341 SDT_PROVIDER_DEFINE(sched);
342 
343 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *",
344  "struct proc *", "uint8_t");
345 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *",
346  "struct proc *", "void *");
347 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *",
348  "struct proc *", "void *", "int");
349 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *",
350  "struct proc *", "uint8_t", "struct thread *");
351 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int");
352 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *",
353  "struct proc *");
354 SDT_PROBE_DEFINE(sched, , , on__cpu);
355 SDT_PROBE_DEFINE(sched, , , remain__cpu);
356 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *",
357  "struct proc *");
358 
359 /*
360  * Print the threads waiting on a run-queue.
361  */
362 static void
363 runq_print(struct runq *rq)
364 {
365  struct rqhead *rqh;
366  struct thread *td;
367  int pri;
368  int j;
369  int i;
370 
371  for (i = 0; i < RQB_LEN; i++) {
372  printf("\t\trunq bits %d 0x%zx\n",
373  i, rq->rq_status.rqb_bits[i]);
374  for (j = 0; j < RQB_BPW; j++)
375  if (rq->rq_status.rqb_bits[i] & (1ul << j)) {
376  pri = j + (i << RQB_L2BPW);
377  rqh = &rq->rq_queues[pri];
378  TAILQ_FOREACH(td, rqh, td_runq) {
379  printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n",
380  td, td->td_name, td->td_priority,
381  td->td_rqindex, pri);
382  }
383  }
384  }
385 }
386 
387 /*
388  * Print the status of a per-cpu thread queue. Should be a ddb show cmd.
389  */
390 void
391 tdq_print(int cpu)
392 {
393  struct tdq *tdq;
394 
395  tdq = TDQ_CPU(cpu);
396 
397  printf("tdq %d:\n", TDQ_ID(tdq));
398  printf("\tlock %p\n", TDQ_LOCKPTR(tdq));
399  printf("\tLock name: %s\n", tdq->tdq_name);
400  printf("\tload: %d\n", tdq->tdq_load);
401  printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt);
402  printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt);
403  printf("\ttimeshare idx: %d\n", tdq->tdq_idx);
404  printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx);
405  printf("\tload transferable: %d\n", tdq->tdq_transferable);
406  printf("\tlowest priority: %d\n", tdq->tdq_lowpri);
407  printf("\trealtime runq:\n");
408  runq_print(&tdq->tdq_realtime);
409  printf("\ttimeshare runq:\n");
410  runq_print(&tdq->tdq_timeshare);
411  printf("\tidle runq:\n");
412  runq_print(&tdq->tdq_idle);
413 }
414 
415 static inline int
416 sched_shouldpreempt(int pri, int cpri, int remote)
417 {
418  /*
419  * If the new priority is not better than the current priority there is
420  * nothing to do.
421  */
422  if (pri >= cpri)
423  return (0);
424  /*
425  * Always preempt idle.
426  */
427  if (cpri >= PRI_MIN_IDLE)
428  return (1);
429  /*
430  * If preemption is disabled don't preempt others.
431  */
432  if (preempt_thresh == 0)
433  return (0);
434  /*
435  * Preempt if we exceed the threshold.
436  */
437  if (pri <= preempt_thresh)
438  return (1);
439  /*
440  * If we're interactive or better and there is non-interactive
441  * or worse running preempt only remote processors.
442  */
443  if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT)
444  return (1);
445  return (0);
446 }
447 
448 /*
449  * Add a thread to the actual run-queue. Keeps transferable counts up to
450  * date with what is actually on the run-queue. Selects the correct
451  * queue position for timeshare threads.
452  */
453 static __inline void
454 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags)
455 {
456  struct td_sched *ts;
457  u_char pri;
458 
459  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
460  THREAD_LOCK_ASSERT(td, MA_OWNED);
461 
462  pri = td->td_priority;
463  ts = td->td_sched;
464  TD_SET_RUNQ(td);
465  if (THREAD_CAN_MIGRATE(td)) {
466  tdq->tdq_transferable++;
467  ts->ts_flags |= TSF_XFERABLE;
468  }
469  if (pri < PRI_MIN_BATCH) {
470  ts->ts_runq = &tdq->tdq_realtime;
471  } else if (pri <= PRI_MAX_BATCH) {
472  ts->ts_runq = &tdq->tdq_timeshare;
473  KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH,
474  ("Invalid priority %d on timeshare runq", pri));
475  /*
476  * This queue contains only priorities between MIN and MAX
477  * realtime. Use the whole queue to represent these values.
478  */
479  if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) {
480  pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE;
481  pri = (pri + tdq->tdq_idx) % RQ_NQS;
482  /*
483  * This effectively shortens the queue by one so we
484  * can have a one slot difference between idx and
485  * ridx while we wait for threads to drain.
486  */
487  if (tdq->tdq_ridx != tdq->tdq_idx &&
488  pri == tdq->tdq_ridx)
489  pri = (unsigned char)(pri - 1) % RQ_NQS;
490  } else
491  pri = tdq->tdq_ridx;
492  runq_add_pri(ts->ts_runq, td, pri, flags);
493  return;
494  } else
495  ts->ts_runq = &tdq->tdq_idle;
496  runq_add(ts->ts_runq, td, flags);
497 }
498 
499 /*
500  * Remove a thread from a run-queue. This typically happens when a thread
501  * is selected to run. Running threads are not on the queue and the
502  * transferable count does not reflect them.
503  */
504 static __inline void
505 tdq_runq_rem(struct tdq *tdq, struct thread *td)
506 {
507  struct td_sched *ts;
508 
509  ts = td->td_sched;
510  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
511  KASSERT(ts->ts_runq != NULL,
512  ("tdq_runq_remove: thread %p null ts_runq", td));
513  if (ts->ts_flags & TSF_XFERABLE) {
514  tdq->tdq_transferable--;
515  ts->ts_flags &= ~TSF_XFERABLE;
516  }
517  if (ts->ts_runq == &tdq->tdq_timeshare) {
518  if (tdq->tdq_idx != tdq->tdq_ridx)
519  runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx);
520  else
521  runq_remove_idx(ts->ts_runq, td, NULL);
522  } else
523  runq_remove(ts->ts_runq, td);
524 }
525 
526 /*
527  * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load
528  * for this thread to the referenced thread queue.
529  */
530 static void
531 tdq_load_add(struct tdq *tdq, struct thread *td)
532 {
533 
534  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
535  THREAD_LOCK_ASSERT(td, MA_OWNED);
536 
537  tdq->tdq_load++;
538  if ((td->td_flags & TDF_NOLOAD) == 0)
539  tdq->tdq_sysload++;
540  KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load);
541  SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load);
542 }
543 
544 /*
545  * Remove the load from a thread that is transitioning to a sleep state or
546  * exiting.
547  */
548 static void
549 tdq_load_rem(struct tdq *tdq, struct thread *td)
550 {
551 
552  THREAD_LOCK_ASSERT(td, MA_OWNED);
553  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
554  KASSERT(tdq->tdq_load != 0,
555  ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq)));
556 
557  tdq->tdq_load--;
558  if ((td->td_flags & TDF_NOLOAD) == 0)
559  tdq->tdq_sysload--;
560  KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load);
561  SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load);
562 }
563 
564 /*
565  * Bound timeshare latency by decreasing slice size as load increases. We
566  * consider the maximum latency as the sum of the threads waiting to run
567  * aside from curthread and target no more than sched_slice latency but
568  * no less than sched_slice_min runtime.
569  */
570 static inline int
571 tdq_slice(struct tdq *tdq)
572 {
573  int load;
574 
575  /*
576  * It is safe to use sys_load here because this is called from
577  * contexts where timeshare threads are running and so there
578  * cannot be higher priority load in the system.
579  */
580  load = tdq->tdq_sysload - 1;
581  if (load >= SCHED_SLICE_MIN_DIVISOR)
582  return (sched_slice_min);
583  if (load <= 1)
584  return (sched_slice);
585  return (sched_slice / load);
586 }
587 
588 /*
589  * Set lowpri to its exact value by searching the run-queue and
590  * evaluating curthread. curthread may be passed as an optimization.
591  */
592 static void
593 tdq_setlowpri(struct tdq *tdq, struct thread *ctd)
594 {
595  struct thread *td;
596 
597  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
598  if (ctd == NULL)
599  ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread;
600  td = tdq_choose(tdq);
601  if (td == NULL || td->td_priority > ctd->td_priority)
602  tdq->tdq_lowpri = ctd->td_priority;
603  else
604  tdq->tdq_lowpri = td->td_priority;
605 }
606 
607 #ifdef SMP
608 struct cpu_search {
609  cpuset_t cs_mask;
610  u_int cs_prefer;
611  int cs_pri; /* Min priority for low. */
612  int cs_limit; /* Max load for low, min load for high. */
613  int cs_cpu;
614  int cs_load;
615 };
616 
617 #define CPU_SEARCH_LOWEST 0x1
618 #define CPU_SEARCH_HIGHEST 0x2
619 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST)
620 
621 #define CPUSET_FOREACH(cpu, mask) \
622  for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \
623  if (CPU_ISSET(cpu, &mask))
624 
625 static __inline int cpu_search(const struct cpu_group *cg, struct cpu_search *low,
626  struct cpu_search *high, const int match);
627 int cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low);
628 int cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high);
629 int cpu_search_both(const struct cpu_group *cg, struct cpu_search *low,
630  struct cpu_search *high);
631 
632 /*
633  * Search the tree of cpu_groups for the lowest or highest loaded cpu
634  * according to the match argument. This routine actually compares the
635  * load on all paths through the tree and finds the least loaded cpu on
636  * the least loaded path, which may differ from the least loaded cpu in
637  * the system. This balances work among caches and busses.
638  *
639  * This inline is instantiated in three forms below using constants for the
640  * match argument. It is reduced to the minimum set for each case. It is
641  * also recursive to the depth of the tree.
642  */
643 static __inline int
644 cpu_search(const struct cpu_group *cg, struct cpu_search *low,
645  struct cpu_search *high, const int match)
646 {
647  struct cpu_search lgroup;
648  struct cpu_search hgroup;
649  cpuset_t cpumask;
650  struct cpu_group *child;
651  struct tdq *tdq;
652  int cpu, i, hload, lload, load, total, rnd, *rndptr;
653 
654  total = 0;
655  cpumask = cg->cg_mask;
656  if (match & CPU_SEARCH_LOWEST) {
657  lload = INT_MAX;
658  lgroup = *low;
659  }
660  if (match & CPU_SEARCH_HIGHEST) {
661  hload = INT_MIN;
662  hgroup = *high;
663  }
664 
665  /* Iterate through the child CPU groups and then remaining CPUs. */
666  for (i = cg->cg_children, cpu = mp_maxid; ; ) {
667  if (i == 0) {
668 #ifdef HAVE_INLINE_FFSL
669  cpu = CPU_FFS(&cpumask) - 1;
670 #else
671  while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask))
672  cpu--;
673 #endif
674  if (cpu < 0)
675  break;
676  child = NULL;
677  } else
678  child = &cg->cg_child[i - 1];
679 
680  if (match & CPU_SEARCH_LOWEST)
681  lgroup.cs_cpu = -1;
682  if (match & CPU_SEARCH_HIGHEST)
683  hgroup.cs_cpu = -1;
684  if (child) { /* Handle child CPU group. */
685  CPU_NAND(&cpumask, &child->cg_mask);
686  switch (match) {
687  case CPU_SEARCH_LOWEST:
688  load = cpu_search_lowest(child, &lgroup);
689  break;
690  case CPU_SEARCH_HIGHEST:
691  load = cpu_search_highest(child, &hgroup);
692  break;
693  case CPU_SEARCH_BOTH:
694  load = cpu_search_both(child, &lgroup, &hgroup);
695  break;
696  }
697  } else { /* Handle child CPU. */
698  CPU_CLR(cpu, &cpumask);
699  tdq = TDQ_CPU(cpu);
700  load = tdq->tdq_load * 256;
701  rndptr = DPCPU_PTR(randomval);
702  rnd = (*rndptr = *rndptr * 69069 + 5) >> 26;
703  if (match & CPU_SEARCH_LOWEST) {
704  if (cpu == low->cs_prefer)
705  load -= 64;
706  /* If that CPU is allowed and get data. */
707  if (tdq->tdq_lowpri > lgroup.cs_pri &&
708  tdq->tdq_load <= lgroup.cs_limit &&
709  CPU_ISSET(cpu, &lgroup.cs_mask)) {
710  lgroup.cs_cpu = cpu;
711  lgroup.cs_load = load - rnd;
712  }
713  }
714  if (match & CPU_SEARCH_HIGHEST)
715  if (tdq->tdq_load >= hgroup.cs_limit &&
716  tdq->tdq_transferable &&
717  CPU_ISSET(cpu, &hgroup.cs_mask)) {
718  hgroup.cs_cpu = cpu;
719  hgroup.cs_load = load - rnd;
720  }
721  }
722  total += load;
723 
724  /* We have info about child item. Compare it. */
725  if (match & CPU_SEARCH_LOWEST) {
726  if (lgroup.cs_cpu >= 0 &&
727  (load < lload ||
728  (load == lload && lgroup.cs_load < low->cs_load))) {
729  lload = load;
730  low->cs_cpu = lgroup.cs_cpu;
731  low->cs_load = lgroup.cs_load;
732  }
733  }
734  if (match & CPU_SEARCH_HIGHEST)
735  if (hgroup.cs_cpu >= 0 &&
736  (load > hload ||
737  (load == hload && hgroup.cs_load > high->cs_load))) {
738  hload = load;
739  high->cs_cpu = hgroup.cs_cpu;
740  high->cs_load = hgroup.cs_load;
741  }
742  if (child) {
743  i--;
744  if (i == 0 && CPU_EMPTY(&cpumask))
745  break;
746  }
747 #ifndef HAVE_INLINE_FFSL
748  else
749  cpu--;
750 #endif
751  }
752  return (total);
753 }
754 
755 /*
756  * cpu_search instantiations must pass constants to maintain the inline
757  * optimization.
758  */
759 int
760 cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low)
761 {
762  return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST);
763 }
764 
765 int
766 cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high)
767 {
768  return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST);
769 }
770 
771 int
772 cpu_search_both(const struct cpu_group *cg, struct cpu_search *low,
773  struct cpu_search *high)
774 {
775  return cpu_search(cg, low, high, CPU_SEARCH_BOTH);
776 }
777 
778 /*
779  * Find the cpu with the least load via the least loaded path that has a
780  * lowpri greater than pri pri. A pri of -1 indicates any priority is
781  * acceptable.
782  */
783 static inline int
784 sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload,
785  int prefer)
786 {
787  struct cpu_search low;
788 
789  low.cs_cpu = -1;
790  low.cs_prefer = prefer;
791  low.cs_mask = mask;
792  low.cs_pri = pri;
793  low.cs_limit = maxload;
794  cpu_search_lowest(cg, &low);
795  return low.cs_cpu;
796 }
797 
798 /*
799  * Find the cpu with the highest load via the highest loaded path.
800  */
801 static inline int
802 sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload)
803 {
804  struct cpu_search high;
805 
806  high.cs_cpu = -1;
807  high.cs_mask = mask;
808  high.cs_limit = minload;
809  cpu_search_highest(cg, &high);
810  return high.cs_cpu;
811 }
812 
813 static void
814 sched_balance_group(struct cpu_group *cg)
815 {
816  cpuset_t hmask, lmask;
817  int high, low, anylow;
818 
819  CPU_FILL(&hmask);
820  for (;;) {
821  high = sched_highest(cg, hmask, 1);
822  /* Stop if there is no more CPU with transferrable threads. */
823  if (high == -1)
824  break;
825  CPU_CLR(high, &hmask);
826  CPU_COPY(&hmask, &lmask);
827  /* Stop if there is no more CPU left for low. */
828  if (CPU_EMPTY(&lmask))
829  break;
830  anylow = 1;
831 nextlow:
832  low = sched_lowest(cg, lmask, -1,
833  TDQ_CPU(high)->tdq_load - 1, high);
834  /* Stop if we looked well and found no less loaded CPU. */
835  if (anylow && low == -1)
836  break;
837  /* Go to next high if we found no less loaded CPU. */
838  if (low == -1)
839  continue;
840  /* Transfer thread from high to low. */
841  if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) {
842  /* CPU that got thread can no longer be a donor. */
843  CPU_CLR(low, &hmask);
844  } else {
845  /*
846  * If failed, then there is no threads on high
847  * that can run on this low. Drop low from low
848  * mask and look for different one.
849  */
850  CPU_CLR(low, &lmask);
851  anylow = 0;
852  goto nextlow;
853  }
854  }
855 }
856 
857 static void
858 sched_balance(void)
859 {
860  struct tdq *tdq;
861 
862  /*
863  * Select a random time between .5 * balance_interval and
864  * 1.5 * balance_interval.
865  */
866  balance_ticks = max(balance_interval / 2, 1);
867  balance_ticks += random() % balance_interval;
868  if (smp_started == 0 || rebalance == 0)
869  return;
870  tdq = TDQ_SELF();
871  TDQ_UNLOCK(tdq);
872  sched_balance_group(cpu_top);
873  TDQ_LOCK(tdq);
874 }
875 
876 /*
877  * Lock two thread queues using their address to maintain lock order.
878  */
879 static void
880 tdq_lock_pair(struct tdq *one, struct tdq *two)
881 {
882  if (one < two) {
883  TDQ_LOCK(one);
884  TDQ_LOCK_FLAGS(two, MTX_DUPOK);
885  } else {
886  TDQ_LOCK(two);
887  TDQ_LOCK_FLAGS(one, MTX_DUPOK);
888  }
889 }
890 
891 /*
892  * Unlock two thread queues. Order is not important here.
893  */
894 static void
895 tdq_unlock_pair(struct tdq *one, struct tdq *two)
896 {
897  TDQ_UNLOCK(one);
898  TDQ_UNLOCK(two);
899 }
900 
901 /*
902  * Transfer load between two imbalanced thread queues.
903  */
904 static int
905 sched_balance_pair(struct tdq *high, struct tdq *low)
906 {
907  int moved;
908  int cpu;
909 
910  tdq_lock_pair(high, low);
911  moved = 0;
912  /*
913  * Determine what the imbalance is and then adjust that to how many
914  * threads we actually have to give up (transferable).
915  */
916  if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load &&
917  (moved = tdq_move(high, low)) > 0) {
918  /*
919  * In case the target isn't the current cpu IPI it to force a
920  * reschedule with the new workload.
921  */
922  cpu = TDQ_ID(low);
923  if (cpu != PCPU_GET(cpuid))
924  ipi_cpu(cpu, IPI_PREEMPT);
925  }
926  tdq_unlock_pair(high, low);
927  return (moved);
928 }
929 
930 /*
931  * Move a thread from one thread queue to another.
932  */
933 static int
934 tdq_move(struct tdq *from, struct tdq *to)
935 {
936  struct td_sched *ts;
937  struct thread *td;
938  struct tdq *tdq;
939  int cpu;
940 
941  TDQ_LOCK_ASSERT(from, MA_OWNED);
942  TDQ_LOCK_ASSERT(to, MA_OWNED);
943 
944  tdq = from;
945  cpu = TDQ_ID(to);
946  td = tdq_steal(tdq, cpu);
947  if (td == NULL)
948  return (0);
949  ts = td->td_sched;
950  /*
951  * Although the run queue is locked the thread may be blocked. Lock
952  * it to clear this and acquire the run-queue lock.
953  */
954  thread_lock(td);
955  /* Drop recursive lock on from acquired via thread_lock(). */
956  TDQ_UNLOCK(from);
957  sched_rem(td);
958  ts->ts_cpu = cpu;
959  td->td_lock = TDQ_LOCKPTR(to);
960  tdq_add(to, td, SRQ_YIELDING);
961  return (1);
962 }
963 
964 /*
965  * This tdq has idled. Try to steal a thread from another cpu and switch
966  * to it.
967  */
968 static int
969 tdq_idled(struct tdq *tdq)
970 {
971  struct cpu_group *cg;
972  struct tdq *steal;
973  cpuset_t mask;
974  int thresh;
975  int cpu;
976 
977  if (smp_started == 0 || steal_idle == 0)
978  return (1);
979  CPU_FILL(&mask);
980  CPU_CLR(PCPU_GET(cpuid), &mask);
981  /* We don't want to be preempted while we're iterating. */
982  spinlock_enter();
983  for (cg = tdq->tdq_cg; cg != NULL; ) {
984  if ((cg->cg_flags & CG_FLAG_THREAD) == 0)
985  thresh = steal_thresh;
986  else
987  thresh = 1;
988  cpu = sched_highest(cg, mask, thresh);
989  if (cpu == -1) {
990  cg = cg->cg_parent;
991  continue;
992  }
993  steal = TDQ_CPU(cpu);
994  CPU_CLR(cpu, &mask);
995  tdq_lock_pair(tdq, steal);
996  if (steal->tdq_load < thresh || steal->tdq_transferable == 0) {
997  tdq_unlock_pair(tdq, steal);
998  continue;
999  }
1000  /*
1001  * If a thread was added while interrupts were disabled don't
1002  * steal one here. If we fail to acquire one due to affinity
1003  * restrictions loop again with this cpu removed from the
1004  * set.
1005  */
1006  if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) {
1007  tdq_unlock_pair(tdq, steal);
1008  continue;
1009  }
1010  spinlock_exit();
1011  TDQ_UNLOCK(steal);
1012  mi_switch(SW_VOL | SWT_IDLE, NULL);
1013  thread_unlock(curthread);
1014 
1015  return (0);
1016  }
1017  spinlock_exit();
1018  return (1);
1019 }
1020 
1021 /*
1022  * Notify a remote cpu of new work. Sends an IPI if criteria are met.
1023  */
1024 static void
1025 tdq_notify(struct tdq *tdq, struct thread *td)
1026 {
1027  struct thread *ctd;
1028  int pri;
1029  int cpu;
1030 
1031  if (tdq->tdq_ipipending)
1032  return;
1033  cpu = td->td_sched->ts_cpu;
1034  pri = td->td_priority;
1035  ctd = pcpu_find(cpu)->pc_curthread;
1036  if (!sched_shouldpreempt(pri, ctd->td_priority, 1))
1037  return;
1038  if (TD_IS_IDLETHREAD(ctd)) {
1039  /*
1040  * If the MD code has an idle wakeup routine try that before
1041  * falling back to IPI.
1042  */
1043  if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu))
1044  return;
1045  }
1046  tdq->tdq_ipipending = 1;
1047  ipi_cpu(cpu, IPI_PREEMPT);
1048 }
1049 
1050 /*
1051  * Steals load from a timeshare queue. Honors the rotating queue head
1052  * index.
1053  */
1054 static struct thread *
1055 runq_steal_from(struct runq *rq, int cpu, u_char start)
1056 {
1057  struct rqbits *rqb;
1058  struct rqhead *rqh;
1059  struct thread *td, *first;
1060  int bit;
1061  int i;
1062 
1063  rqb = &rq->rq_status;
1064  bit = start & (RQB_BPW -1);
1065  first = NULL;
1066 again:
1067  for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) {
1068  if (rqb->rqb_bits[i] == 0)
1069  continue;
1070  if (bit == 0)
1071  bit = RQB_FFS(rqb->rqb_bits[i]);
1072  for (; bit < RQB_BPW; bit++) {
1073  if ((rqb->rqb_bits[i] & (1ul << bit)) == 0)
1074  continue;
1075  rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)];
1076  TAILQ_FOREACH(td, rqh, td_runq) {
1077  if (first && THREAD_CAN_MIGRATE(td) &&
1078  THREAD_CAN_SCHED(td, cpu))
1079  return (td);
1080  first = td;
1081  }
1082  }
1083  }
1084  if (start != 0) {
1085  start = 0;
1086  goto again;
1087  }
1088 
1089  if (first && THREAD_CAN_MIGRATE(first) &&
1090  THREAD_CAN_SCHED(first, cpu))
1091  return (first);
1092  return (NULL);
1093 }
1094 
1095 /*
1096  * Steals load from a standard linear queue.
1097  */
1098 static struct thread *
1099 runq_steal(struct runq *rq, int cpu)
1100 {
1101  struct rqhead *rqh;
1102  struct rqbits *rqb;
1103  struct thread *td;
1104  int word;
1105  int bit;
1106 
1107  rqb = &rq->rq_status;
1108  for (word = 0; word < RQB_LEN; word++) {
1109  if (rqb->rqb_bits[word] == 0)
1110  continue;
1111  for (bit = 0; bit < RQB_BPW; bit++) {
1112  if ((rqb->rqb_bits[word] & (1ul << bit)) == 0)
1113  continue;
1114  rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)];
1115  TAILQ_FOREACH(td, rqh, td_runq)
1116  if (THREAD_CAN_MIGRATE(td) &&
1117  THREAD_CAN_SCHED(td, cpu))
1118  return (td);
1119  }
1120  }
1121  return (NULL);
1122 }
1123 
1124 /*
1125  * Attempt to steal a thread in priority order from a thread queue.
1126  */
1127 static struct thread *
1128 tdq_steal(struct tdq *tdq, int cpu)
1129 {
1130  struct thread *td;
1131 
1132  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
1133  if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL)
1134  return (td);
1135  if ((td = runq_steal_from(&tdq->tdq_timeshare,
1136  cpu, tdq->tdq_ridx)) != NULL)
1137  return (td);
1138  return (runq_steal(&tdq->tdq_idle, cpu));
1139 }
1140 
1141 /*
1142  * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the
1143  * current lock and returns with the assigned queue locked.
1144  */
1145 static inline struct tdq *
1146 sched_setcpu(struct thread *td, int cpu, int flags)
1147 {
1148 
1149  struct tdq *tdq;
1150 
1151  THREAD_LOCK_ASSERT(td, MA_OWNED);
1152  tdq = TDQ_CPU(cpu);
1153  td->td_sched->ts_cpu = cpu;
1154  /*
1155  * If the lock matches just return the queue.
1156  */
1157  if (td->td_lock == TDQ_LOCKPTR(tdq))
1158  return (tdq);
1159 #ifdef notyet
1160  /*
1161  * If the thread isn't running its lockptr is a
1162  * turnstile or a sleepqueue. We can just lock_set without
1163  * blocking.
1164  */
1165  if (TD_CAN_RUN(td)) {
1166  TDQ_LOCK(tdq);
1167  thread_lock_set(td, TDQ_LOCKPTR(tdq));
1168  return (tdq);
1169  }
1170 #endif
1171  /*
1172  * The hard case, migration, we need to block the thread first to
1173  * prevent order reversals with other cpus locks.
1174  */
1175  spinlock_enter();
1176  thread_lock_block(td);
1177  TDQ_LOCK(tdq);
1178  thread_lock_unblock(td, TDQ_LOCKPTR(tdq));
1179  spinlock_exit();
1180  return (tdq);
1181 }
1182 
1183 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding");
1184 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity");
1185 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity");
1186 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load");
1187 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu");
1188 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration");
1189 
1190 static int
1191 sched_pickcpu(struct thread *td, int flags)
1192 {
1193  struct cpu_group *cg, *ccg;
1194  struct td_sched *ts;
1195  struct tdq *tdq;
1196  cpuset_t mask;
1197  int cpu, pri, self;
1198 
1199  self = PCPU_GET(cpuid);
1200  ts = td->td_sched;
1201  if (smp_started == 0)
1202  return (self);
1203  /*
1204  * Don't migrate a running thread from sched_switch().
1205  */
1206  if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td))
1207  return (ts->ts_cpu);
1208  /*
1209  * Prefer to run interrupt threads on the processors that generate
1210  * the interrupt.
1211  */
1212  pri = td->td_priority;
1213  if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) &&
1214  curthread->td_intr_nesting_level && ts->ts_cpu != self) {
1215  SCHED_STAT_INC(pickcpu_intrbind);
1216  ts->ts_cpu = self;
1217  if (TDQ_CPU(self)->tdq_lowpri > pri) {
1218  SCHED_STAT_INC(pickcpu_affinity);
1219  return (ts->ts_cpu);
1220  }
1221  }
1222  /*
1223  * If the thread can run on the last cpu and the affinity has not
1224  * expired or it is idle run it there.
1225  */
1226  tdq = TDQ_CPU(ts->ts_cpu);
1227  cg = tdq->tdq_cg;
1228  if (THREAD_CAN_SCHED(td, ts->ts_cpu) &&
1229  tdq->tdq_lowpri >= PRI_MIN_IDLE &&
1230  SCHED_AFFINITY(ts, CG_SHARE_L2)) {
1231  if (cg->cg_flags & CG_FLAG_THREAD) {
1232  CPUSET_FOREACH(cpu, cg->cg_mask) {
1233  if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE)
1234  break;
1235  }
1236  } else
1237  cpu = INT_MAX;
1238  if (cpu > mp_maxid) {
1239  SCHED_STAT_INC(pickcpu_idle_affinity);
1240  return (ts->ts_cpu);
1241  }
1242  }
1243  /*
1244  * Search for the last level cache CPU group in the tree.
1245  * Skip caches with expired affinity time and SMT groups.
1246  * Affinity to higher level caches will be handled less aggressively.
1247  */
1248  for (ccg = NULL; cg != NULL; cg = cg->cg_parent) {
1249  if (cg->cg_flags & CG_FLAG_THREAD)
1250  continue;
1251  if (!SCHED_AFFINITY(ts, cg->cg_level))
1252  continue;
1253  ccg = cg;
1254  }
1255  if (ccg != NULL)
1256  cg = ccg;
1257  cpu = -1;
1258  /* Search the group for the less loaded idle CPU we can run now. */
1259  mask = td->td_cpuset->cs_mask;
1260  if (cg != NULL && cg != cpu_top &&
1261  CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0)
1262  cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE),
1263  INT_MAX, ts->ts_cpu);
1264  /* Search globally for the less loaded CPU we can run now. */
1265  if (cpu == -1)
1266  cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu);
1267  /* Search globally for the less loaded CPU. */
1268  if (cpu == -1)
1269  cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu);
1270  KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu."));
1271  /*
1272  * Compare the lowest loaded cpu to current cpu.
1273  */
1274  if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri &&
1275  TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE &&
1276  TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) {
1277  SCHED_STAT_INC(pickcpu_local);
1278  cpu = self;
1279  } else
1280  SCHED_STAT_INC(pickcpu_lowest);
1281  if (cpu != ts->ts_cpu)
1282  SCHED_STAT_INC(pickcpu_migration);
1283  return (cpu);
1284 }
1285 #endif
1286 
1287 /*
1288  * Pick the highest priority task we have and return it.
1289  */
1290 static struct thread *
1291 tdq_choose(struct tdq *tdq)
1292 {
1293  struct thread *td;
1294 
1295  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
1296  td = runq_choose(&tdq->tdq_realtime);
1297  if (td != NULL)
1298  return (td);
1299  td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx);
1300  if (td != NULL) {
1301  KASSERT(td->td_priority >= PRI_MIN_BATCH,
1302  ("tdq_choose: Invalid priority on timeshare queue %d",
1303  td->td_priority));
1304  return (td);
1305  }
1306  td = runq_choose(&tdq->tdq_idle);
1307  if (td != NULL) {
1308  KASSERT(td->td_priority >= PRI_MIN_IDLE,
1309  ("tdq_choose: Invalid priority on idle queue %d",
1310  td->td_priority));
1311  return (td);
1312  }
1313 
1314  return (NULL);
1315 }
1316 
1317 /*
1318  * Initialize a thread queue.
1319  */
1320 static void
1321 tdq_setup(struct tdq *tdq)
1322 {
1323 
1324  if (bootverbose)
1325  printf("ULE: setup cpu %d\n", TDQ_ID(tdq));
1326  runq_init(&tdq->tdq_realtime);
1327  runq_init(&tdq->tdq_timeshare);
1328  runq_init(&tdq->tdq_idle);
1329  snprintf(tdq->tdq_name, sizeof(tdq->tdq_name),
1330  "sched lock %d", (int)TDQ_ID(tdq));
1331  mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock",
1332  MTX_SPIN | MTX_RECURSE);
1333 #ifdef KTR
1334  snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname),
1335  "CPU %d load", (int)TDQ_ID(tdq));
1336 #endif
1337 }
1338 
1339 #ifdef SMP
1340 static void
1341 sched_setup_smp(void)
1342 {
1343  struct tdq *tdq;
1344  int i;
1345 
1346  cpu_top = smp_topo();
1347  CPU_FOREACH(i) {
1348  tdq = TDQ_CPU(i);
1349  tdq_setup(tdq);
1350  tdq->tdq_cg = smp_topo_find(cpu_top, i);
1351  if (tdq->tdq_cg == NULL)
1352  panic("Can't find cpu group for %d\n", i);
1353  }
1354  balance_tdq = TDQ_SELF();
1355  sched_balance();
1356 }
1357 #endif
1358 
1359 /*
1360  * Setup the thread queues and initialize the topology based on MD
1361  * information.
1362  */
1363 static void
1365 {
1366  struct tdq *tdq;
1367 
1368  tdq = TDQ_SELF();
1369 #ifdef SMP
1370  sched_setup_smp();
1371 #else
1372  tdq_setup(tdq);
1373 #endif
1374 
1375  /* Add thread0's load since it's running. */
1376  TDQ_LOCK(tdq);
1377  thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF());
1378  tdq_load_add(tdq, &thread0);
1379  tdq->tdq_lowpri = thread0.td_priority;
1380  TDQ_UNLOCK(tdq);
1381 }
1382 
1383 /*
1384  * This routine determines time constants after stathz and hz are setup.
1385  */
1386 /* ARGSUSED */
1387 static void
1389 {
1390  int incr;
1391 
1392  realstathz = stathz ? stathz : hz;
1395  hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
1396  realstathz);
1397 
1398  /*
1399  * tickincr is shifted out by 10 to avoid rounding errors due to
1400  * hz not being evenly divisible by stathz on all platforms.
1401  */
1402  incr = (hz << SCHED_TICK_SHIFT) / realstathz;
1403  /*
1404  * This does not work for values of stathz that are more than
1405  * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen.
1406  */
1407  if (incr == 0)
1408  incr = 1;
1409  tickincr = incr;
1410 #ifdef SMP
1411  /*
1412  * Set the default balance interval now that we know
1413  * what realstathz is.
1414  */
1415  balance_interval = realstathz;
1416  affinity = SCHED_AFFINITY_DEFAULT;
1417 #endif
1418  if (sched_idlespinthresh < 0)
1419  sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz;
1420 }
1421 
1422 
1423 /*
1424  * This is the core of the interactivity algorithm. Determines a score based
1425  * on past behavior. It is the ratio of sleep time to run time scaled to
1426  * a [0, 100] integer. This is the voluntary sleep time of a process, which
1427  * differs from the cpu usage because it does not account for time spent
1428  * waiting on a run-queue. Would be prettier if we had floating point.
1429  */
1430 static int
1431 sched_interact_score(struct thread *td)
1432 {
1433  struct td_sched *ts;
1434  int div;
1435 
1436  ts = td->td_sched;
1437  /*
1438  * The score is only needed if this is likely to be an interactive
1439  * task. Don't go through the expense of computing it if there's
1440  * no chance.
1441  */
1443  ts->ts_runtime >= ts->ts_slptime)
1444  return (SCHED_INTERACT_HALF);
1445 
1446  if (ts->ts_runtime > ts->ts_slptime) {
1447  div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF);
1448  return (SCHED_INTERACT_HALF +
1449  (SCHED_INTERACT_HALF - (ts->ts_slptime / div)));
1450  }
1451  if (ts->ts_slptime > ts->ts_runtime) {
1452  div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF);
1453  return (ts->ts_runtime / div);
1454  }
1455  /* runtime == slptime */
1456  if (ts->ts_runtime)
1457  return (SCHED_INTERACT_HALF);
1458 
1459  /*
1460  * This can happen if slptime and runtime are 0.
1461  */
1462  return (0);
1463 
1464 }
1465 
1466 /*
1467  * Scale the scheduling priority according to the "interactivity" of this
1468  * process.
1469  */
1470 static void
1471 sched_priority(struct thread *td)
1472 {
1473  int score;
1474  int pri;
1475 
1476  if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
1477  return;
1478  /*
1479  * If the score is interactive we place the thread in the realtime
1480  * queue with a priority that is less than kernel and interrupt
1481  * priorities. These threads are not subject to nice restrictions.
1482  *
1483  * Scores greater than this are placed on the normal timeshare queue
1484  * where the priority is partially decided by the most recent cpu
1485  * utilization and the rest is decided by nice value.
1486  *
1487  * The nice value of the process has a linear effect on the calculated
1488  * score. Negative nice values make it easier for a thread to be
1489  * considered interactive.
1490  */
1491  score = imax(0, sched_interact_score(td) + td->td_proc->p_nice);
1492  if (score < sched_interact) {
1493  pri = PRI_MIN_INTERACT;
1494  pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) /
1495  sched_interact) * score;
1496  KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT,
1497  ("sched_priority: invalid interactive priority %d score %d",
1498  pri, score));
1499  } else {
1500  pri = SCHED_PRI_MIN;
1501  if (td->td_sched->ts_ticks)
1502  pri += min(SCHED_PRI_TICKS(td->td_sched),
1503  SCHED_PRI_RANGE - 1);
1504  pri += SCHED_PRI_NICE(td->td_proc->p_nice);
1505  KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH,
1506  ("sched_priority: invalid priority %d: nice %d, "
1507  "ticks %d ftick %d ltick %d tick pri %d",
1508  pri, td->td_proc->p_nice, td->td_sched->ts_ticks,
1509  td->td_sched->ts_ftick, td->td_sched->ts_ltick,
1510  SCHED_PRI_TICKS(td->td_sched)));
1511  }
1512  sched_user_prio(td, pri);
1513 
1514  return;
1515 }
1516 
1517 /*
1518  * This routine enforces a maximum limit on the amount of scheduling history
1519  * kept. It is called after either the slptime or runtime is adjusted. This
1520  * function is ugly due to integer math.
1521  */
1522 static void
1523 sched_interact_update(struct thread *td)
1524 {
1525  struct td_sched *ts;
1526  u_int sum;
1527 
1528  ts = td->td_sched;
1529  sum = ts->ts_runtime + ts->ts_slptime;
1530  if (sum < SCHED_SLP_RUN_MAX)
1531  return;
1532  /*
1533  * This only happens from two places:
1534  * 1) We have added an unusual amount of run time from fork_exit.
1535  * 2) We have added an unusual amount of sleep time from sched_sleep().
1536  */
1537  if (sum > SCHED_SLP_RUN_MAX * 2) {
1538  if (ts->ts_runtime > ts->ts_slptime) {
1540  ts->ts_slptime = 1;
1541  } else {
1543  ts->ts_runtime = 1;
1544  }
1545  return;
1546  }
1547  /*
1548  * If we have exceeded by more than 1/5th then the algorithm below
1549  * will not bring us back into range. Dividing by two here forces
1550  * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX]
1551  */
1552  if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) {
1553  ts->ts_runtime /= 2;
1554  ts->ts_slptime /= 2;
1555  return;
1556  }
1557  ts->ts_runtime = (ts->ts_runtime / 5) * 4;
1558  ts->ts_slptime = (ts->ts_slptime / 5) * 4;
1559 }
1560 
1561 /*
1562  * Scale back the interactivity history when a child thread is created. The
1563  * history is inherited from the parent but the thread may behave totally
1564  * differently. For example, a shell spawning a compiler process. We want
1565  * to learn that the compiler is behaving badly very quickly.
1566  */
1567 static void
1568 sched_interact_fork(struct thread *td)
1569 {
1570  int ratio;
1571  int sum;
1572 
1573  sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime;
1574  if (sum > SCHED_SLP_RUN_FORK) {
1575  ratio = sum / SCHED_SLP_RUN_FORK;
1576  td->td_sched->ts_runtime /= ratio;
1577  td->td_sched->ts_slptime /= ratio;
1578  }
1579 }
1580 
1581 /*
1582  * Called from proc0_init() to setup the scheduler fields.
1583  */
1584 void
1586 {
1587 
1588  /*
1589  * Set up the scheduler specific parts of proc0.
1590  */
1591  proc0.p_sched = NULL; /* XXX */
1592  thread0.td_sched = &td_sched0;
1595  td_sched0.ts_slice = 0;
1596 }
1597 
1598 /*
1599  * This is only somewhat accurate since given many processes of the same
1600  * priority they will switch when their slices run out, which will be
1601  * at most sched_slice stathz ticks.
1602  */
1603 int
1605 {
1606 
1607  /* Convert sched_slice from stathz to hz. */
1608  return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz));
1609 }
1610 
1611 /*
1612  * Update the percent cpu tracking information when it is requested or
1613  * the total history exceeds the maximum. We keep a sliding history of
1614  * tick counts that slowly decays. This is less precise than the 4BSD
1615  * mechanism since it happens with less regular and frequent events.
1616  */
1617 static void
1618 sched_pctcpu_update(struct td_sched *ts, int run)
1619 {
1620  int t = ticks;
1621 
1622  if (t - ts->ts_ltick >= SCHED_TICK_TARG) {
1623  ts->ts_ticks = 0;
1624  ts->ts_ftick = t - SCHED_TICK_TARG;
1625  } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) {
1626  ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) *
1627  (ts->ts_ltick - (t - SCHED_TICK_TARG));
1628  ts->ts_ftick = t - SCHED_TICK_TARG;
1629  }
1630  if (run)
1631  ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT;
1632  ts->ts_ltick = t;
1633 }
1634 
1635 /*
1636  * Adjust the priority of a thread. Move it to the appropriate run-queue
1637  * if necessary. This is the back-end for several priority related
1638  * functions.
1639  */
1640 static void
1641 sched_thread_priority(struct thread *td, u_char prio)
1642 {
1643  struct td_sched *ts;
1644  struct tdq *tdq;
1645  int oldpri;
1646 
1647  KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio",
1648  "prio:%d", td->td_priority, "new prio:%d", prio,
1649  KTR_ATTR_LINKED, sched_tdname(curthread));
1650  SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio);
1651  if (td != curthread && prio < td->td_priority) {
1652  KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread),
1653  "lend prio", "prio:%d", td->td_priority, "new prio:%d",
1654  prio, KTR_ATTR_LINKED, sched_tdname(td));
1655  SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio,
1656  curthread);
1657  }
1658  ts = td->td_sched;
1659  THREAD_LOCK_ASSERT(td, MA_OWNED);
1660  if (td->td_priority == prio)
1661  return;
1662  /*
1663  * If the priority has been elevated due to priority
1664  * propagation, we may have to move ourselves to a new
1665  * queue. This could be optimized to not re-add in some
1666  * cases.
1667  */
1668  if (TD_ON_RUNQ(td) && prio < td->td_priority) {
1669  sched_rem(td);
1670  td->td_priority = prio;
1671  sched_add(td, SRQ_BORROWING);
1672  return;
1673  }
1674  /*
1675  * If the thread is currently running we may have to adjust the lowpri
1676  * information so other cpus are aware of our current priority.
1677  */
1678  if (TD_IS_RUNNING(td)) {
1679  tdq = TDQ_CPU(ts->ts_cpu);
1680  oldpri = td->td_priority;
1681  td->td_priority = prio;
1682  if (prio < tdq->tdq_lowpri)
1683  tdq->tdq_lowpri = prio;
1684  else if (tdq->tdq_lowpri == oldpri)
1685  tdq_setlowpri(tdq, td);
1686  return;
1687  }
1688  td->td_priority = prio;
1689 }
1690 
1691 /*
1692  * Update a thread's priority when it is lent another thread's
1693  * priority.
1694  */
1695 void
1696 sched_lend_prio(struct thread *td, u_char prio)
1697 {
1698 
1699  td->td_flags |= TDF_BORROWING;
1700  sched_thread_priority(td, prio);
1701 }
1702 
1703 /*
1704  * Restore a thread's priority when priority propagation is
1705  * over. The prio argument is the minimum priority the thread
1706  * needs to have to satisfy other possible priority lending
1707  * requests. If the thread's regular priority is less
1708  * important than prio, the thread will keep a priority boost
1709  * of prio.
1710  */
1711 void
1712 sched_unlend_prio(struct thread *td, u_char prio)
1713 {
1714  u_char base_pri;
1715 
1716  if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
1717  td->td_base_pri <= PRI_MAX_TIMESHARE)
1718  base_pri = td->td_user_pri;
1719  else
1720  base_pri = td->td_base_pri;
1721  if (prio >= base_pri) {
1722  td->td_flags &= ~TDF_BORROWING;
1723  sched_thread_priority(td, base_pri);
1724  } else
1725  sched_lend_prio(td, prio);
1726 }
1727 
1728 /*
1729  * Standard entry for setting the priority to an absolute value.
1730  */
1731 void
1732 sched_prio(struct thread *td, u_char prio)
1733 {
1734  u_char oldprio;
1735 
1736  /* First, update the base priority. */
1737  td->td_base_pri = prio;
1738 
1739  /*
1740  * If the thread is borrowing another thread's priority, don't
1741  * ever lower the priority.
1742  */
1743  if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
1744  return;
1745 
1746  /* Change the real priority. */
1747  oldprio = td->td_priority;
1748  sched_thread_priority(td, prio);
1749 
1750  /*
1751  * If the thread is on a turnstile, then let the turnstile update
1752  * its state.
1753  */
1754  if (TD_ON_LOCK(td) && oldprio != prio)
1755  turnstile_adjust(td, oldprio);
1756 }
1757 
1758 /*
1759  * Set the base user priority, does not effect current running priority.
1760  */
1761 void
1762 sched_user_prio(struct thread *td, u_char prio)
1763 {
1764 
1765  td->td_base_user_pri = prio;
1766  if (td->td_lend_user_pri <= prio)
1767  return;
1768  td->td_user_pri = prio;
1769 }
1770 
1771 void
1772 sched_lend_user_prio(struct thread *td, u_char prio)
1773 {
1774 
1775  THREAD_LOCK_ASSERT(td, MA_OWNED);
1776  td->td_lend_user_pri = prio;
1777  td->td_user_pri = min(prio, td->td_base_user_pri);
1778  if (td->td_priority > td->td_user_pri)
1779  sched_prio(td, td->td_user_pri);
1780  else if (td->td_priority != td->td_user_pri)
1781  td->td_flags |= TDF_NEEDRESCHED;
1782 }
1783 
1784 /*
1785  * Handle migration from sched_switch(). This happens only for
1786  * cpu binding.
1787  */
1788 static struct mtx *
1789 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags)
1790 {
1791  struct tdq *tdn;
1792 
1793  tdn = TDQ_CPU(td->td_sched->ts_cpu);
1794 #ifdef SMP
1795  tdq_load_rem(tdq, td);
1796  /*
1797  * Do the lock dance required to avoid LOR. We grab an extra
1798  * spinlock nesting to prevent preemption while we're
1799  * not holding either run-queue lock.
1800  */
1801  spinlock_enter();
1802  thread_lock_block(td); /* This releases the lock on tdq. */
1803 
1804  /*
1805  * Acquire both run-queue locks before placing the thread on the new
1806  * run-queue to avoid deadlocks created by placing a thread with a
1807  * blocked lock on the run-queue of a remote processor. The deadlock
1808  * occurs when a third processor attempts to lock the two queues in
1809  * question while the target processor is spinning with its own
1810  * run-queue lock held while waiting for the blocked lock to clear.
1811  */
1812  tdq_lock_pair(tdn, tdq);
1813  tdq_add(tdn, td, flags);
1814  tdq_notify(tdn, td);
1815  TDQ_UNLOCK(tdn);
1816  spinlock_exit();
1817 #endif
1818  return (TDQ_LOCKPTR(tdn));
1819 }
1820 
1821 /*
1822  * Variadic version of thread_lock_unblock() that does not assume td_lock
1823  * is blocked.
1824  */
1825 static inline void
1826 thread_unblock_switch(struct thread *td, struct mtx *mtx)
1827 {
1828  atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock,
1829  (uintptr_t)mtx);
1830 }
1831 
1832 /*
1833  * Switch threads. This function has to handle threads coming in while
1834  * blocked for some reason, running, or idle. It also must deal with
1835  * migrating a thread from one queue to another as running threads may
1836  * be assigned elsewhere via binding.
1837  */
1838 void
1839 sched_switch(struct thread *td, struct thread *newtd, int flags)
1840 {
1841  struct tdq *tdq;
1842  struct td_sched *ts;
1843  struct mtx *mtx;
1844  int srqflag;
1845  int cpuid, preempted;
1846 
1847  THREAD_LOCK_ASSERT(td, MA_OWNED);
1848  KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument"));
1849 
1850  cpuid = PCPU_GET(cpuid);
1851  tdq = TDQ_CPU(cpuid);
1852  ts = td->td_sched;
1853  mtx = td->td_lock;
1854  sched_pctcpu_update(ts, 1);
1855  ts->ts_rltick = ticks;
1856  td->td_lastcpu = td->td_oncpu;
1857  td->td_oncpu = NOCPU;
1858  preempted = !(td->td_flags & TDF_SLICEEND);
1859  td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND);
1860  td->td_owepreempt = 0;
1861  if (!TD_IS_IDLETHREAD(td))
1862  tdq->tdq_switchcnt++;
1863  /*
1864  * The lock pointer in an idle thread should never change. Reset it
1865  * to CAN_RUN as well.
1866  */
1867  if (TD_IS_IDLETHREAD(td)) {
1868  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1869  TD_SET_CAN_RUN(td);
1870  } else if (TD_IS_RUNNING(td)) {
1871  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1872  srqflag = preempted ?
1873  SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
1874  SRQ_OURSELF|SRQ_YIELDING;
1875 #ifdef SMP
1876  if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu))
1877  ts->ts_cpu = sched_pickcpu(td, 0);
1878 #endif
1879  if (ts->ts_cpu == cpuid)
1880  tdq_runq_add(tdq, td, srqflag);
1881  else {
1882  KASSERT(THREAD_CAN_MIGRATE(td) ||
1883  (ts->ts_flags & TSF_BOUND) != 0,
1884  ("Thread %p shouldn't migrate", td));
1885  mtx = sched_switch_migrate(tdq, td, srqflag);
1886  }
1887  } else {
1888  /* This thread must be going to sleep. */
1889  TDQ_LOCK(tdq);
1890  mtx = thread_lock_block(td);
1891  tdq_load_rem(tdq, td);
1892  }
1893  /*
1894  * We enter here with the thread blocked and assigned to the
1895  * appropriate cpu run-queue or sleep-queue and with the current
1896  * thread-queue locked.
1897  */
1898  TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED);
1899  newtd = choosethread();
1900  /*
1901  * Call the MD code to switch contexts if necessary.
1902  */
1903  if (td != newtd) {
1904 #ifdef HWPMC_HOOKS
1905  if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1906  PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
1907 #endif
1908  SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc);
1909  lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object);
1910  TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd;
1911  sched_pctcpu_update(newtd->td_sched, 0);
1912 
1913 #ifdef KDTRACE_HOOKS
1914  /*
1915  * If DTrace has set the active vtime enum to anything
1916  * other than INACTIVE (0), then it should have set the
1917  * function to call.
1918  */
1919  if (dtrace_vtime_active)
1920  (*dtrace_vtime_switch_func)(newtd);
1921 #endif
1922 
1923  cpu_switch(td, newtd, mtx);
1924  /*
1925  * We may return from cpu_switch on a different cpu. However,
1926  * we always return with td_lock pointing to the current cpu's
1927  * run queue lock.
1928  */
1929  cpuid = PCPU_GET(cpuid);
1930  tdq = TDQ_CPU(cpuid);
1931  lock_profile_obtain_lock_success(
1932  &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__);
1933 
1934  SDT_PROBE0(sched, , , on__cpu);
1935 #ifdef HWPMC_HOOKS
1936  if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1937  PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
1938 #endif
1939  } else {
1940  thread_unblock_switch(td, mtx);
1941  SDT_PROBE0(sched, , , remain__cpu);
1942  }
1943  /*
1944  * Assert that all went well and return.
1945  */
1946  TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED);
1947  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1948  td->td_oncpu = cpuid;
1949 }
1950 
1951 /*
1952  * Adjust thread priorities as a result of a nice request.
1953  */
1954 void
1955 sched_nice(struct proc *p, int nice)
1956 {
1957  struct thread *td;
1958 
1959  PROC_LOCK_ASSERT(p, MA_OWNED);
1960 
1961  p->p_nice = nice;
1962  FOREACH_THREAD_IN_PROC(p, td) {
1963  thread_lock(td);
1964  sched_priority(td);
1965  sched_prio(td, td->td_base_user_pri);
1966  thread_unlock(td);
1967  }
1968 }
1969 
1970 /*
1971  * Record the sleep time for the interactivity scorer.
1972  */
1973 void
1974 sched_sleep(struct thread *td, int prio)
1975 {
1976 
1977  THREAD_LOCK_ASSERT(td, MA_OWNED);
1978 
1979  td->td_slptick = ticks;
1980  if (TD_IS_SUSPENDED(td) || prio >= PSOCK)
1981  td->td_flags |= TDF_CANSWAP;
1982  if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
1983  return;
1984  if (static_boost == 1 && prio)
1985  sched_prio(td, prio);
1986  else if (static_boost && td->td_priority > static_boost)
1987  sched_prio(td, static_boost);
1988 }
1989 
1990 /*
1991  * Schedule a thread to resume execution and record how long it voluntarily
1992  * slept. We also update the pctcpu, interactivity, and priority.
1993  */
1994 void
1995 sched_wakeup(struct thread *td)
1996 {
1997  struct td_sched *ts;
1998  int slptick;
1999 
2000  THREAD_LOCK_ASSERT(td, MA_OWNED);
2001  ts = td->td_sched;
2002  td->td_flags &= ~TDF_CANSWAP;
2003  /*
2004  * If we slept for more than a tick update our interactivity and
2005  * priority.
2006  */
2007  slptick = td->td_slptick;
2008  td->td_slptick = 0;
2009  if (slptick && slptick != ticks) {
2010  ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT;
2012  sched_pctcpu_update(ts, 0);
2013  }
2014  /*
2015  * Reset the slice value since we slept and advanced the round-robin.
2016  */
2017  ts->ts_slice = 0;
2018  sched_add(td, SRQ_BORING);
2019 }
2020 
2021 /*
2022  * Penalize the parent for creating a new child and initialize the child's
2023  * priority.
2024  */
2025 void
2026 sched_fork(struct thread *td, struct thread *child)
2027 {
2028  THREAD_LOCK_ASSERT(td, MA_OWNED);
2029  sched_pctcpu_update(td->td_sched, 1);
2030  sched_fork_thread(td, child);
2031  /*
2032  * Penalize the parent and child for forking.
2033  */
2034  sched_interact_fork(child);
2035  sched_priority(child);
2036  td->td_sched->ts_runtime += tickincr;
2038  sched_priority(td);
2039 }
2040 
2041 /*
2042  * Fork a new thread, may be within the same process.
2043  */
2044 void
2045 sched_fork_thread(struct thread *td, struct thread *child)
2046 {
2047  struct td_sched *ts;
2048  struct td_sched *ts2;
2049  struct tdq *tdq;
2050 
2051  tdq = TDQ_SELF();
2052  THREAD_LOCK_ASSERT(td, MA_OWNED);
2053  /*
2054  * Initialize child.
2055  */
2056  ts = td->td_sched;
2057  ts2 = child->td_sched;
2058  child->td_lock = TDQ_LOCKPTR(tdq);
2059  child->td_cpuset = cpuset_ref(td->td_cpuset);
2060  ts2->ts_cpu = ts->ts_cpu;
2061  ts2->ts_flags = 0;
2062  /*
2063  * Grab our parents cpu estimation information.
2064  */
2065  ts2->ts_ticks = ts->ts_ticks;
2066  ts2->ts_ltick = ts->ts_ltick;
2067  ts2->ts_ftick = ts->ts_ftick;
2068  /*
2069  * Do not inherit any borrowed priority from the parent.
2070  */
2071  child->td_priority = child->td_base_pri;
2072  /*
2073  * And update interactivity score.
2074  */
2075  ts2->ts_slptime = ts->ts_slptime;
2076  ts2->ts_runtime = ts->ts_runtime;
2077  /* Attempt to quickly learn interactivity. */
2078  ts2->ts_slice = tdq_slice(tdq) - sched_slice_min;
2079 #ifdef KTR
2080  bzero(ts2->ts_name, sizeof(ts2->ts_name));
2081 #endif
2082 }
2083 
2084 /*
2085  * Adjust the priority class of a thread.
2086  */
2087 void
2088 sched_class(struct thread *td, int class)
2089 {
2090 
2091  THREAD_LOCK_ASSERT(td, MA_OWNED);
2092  if (td->td_pri_class == class)
2093  return;
2094  td->td_pri_class = class;
2095 }
2096 
2097 /*
2098  * Return some of the child's priority and interactivity to the parent.
2099  */
2100 void
2101 sched_exit(struct proc *p, struct thread *child)
2102 {
2103  struct thread *td;
2104 
2105  KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit",
2106  "prio:%d", child->td_priority);
2107  PROC_LOCK_ASSERT(p, MA_OWNED);
2108  td = FIRST_THREAD_IN_PROC(p);
2109  sched_exit_thread(td, child);
2110 }
2111 
2112 /*
2113  * Penalize another thread for the time spent on this one. This helps to
2114  * worsen the priority and interactivity of processes which schedule batch
2115  * jobs such as make. This has little effect on the make process itself but
2116  * causes new processes spawned by it to receive worse scores immediately.
2117  */
2118 void
2119 sched_exit_thread(struct thread *td, struct thread *child)
2120 {
2121 
2122  KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit",
2123  "prio:%d", child->td_priority);
2124  /*
2125  * Give the child's runtime to the parent without returning the
2126  * sleep time as a penalty to the parent. This causes shells that
2127  * launch expensive things to mark their children as expensive.
2128  */
2129  thread_lock(td);
2130  td->td_sched->ts_runtime += child->td_sched->ts_runtime;
2132  sched_priority(td);
2133  thread_unlock(td);
2134 }
2135 
2136 void
2137 sched_preempt(struct thread *td)
2138 {
2139  struct tdq *tdq;
2140 
2141  SDT_PROBE2(sched, , , surrender, td, td->td_proc);
2142 
2143  thread_lock(td);
2144  tdq = TDQ_SELF();
2145  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2146  tdq->tdq_ipipending = 0;
2147  if (td->td_priority > tdq->tdq_lowpri) {
2148  int flags;
2149 
2150  flags = SW_INVOL | SW_PREEMPT;
2151  if (td->td_critnest > 1)
2152  td->td_owepreempt = 1;
2153  else if (TD_IS_IDLETHREAD(td))
2154  mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL);
2155  else
2156  mi_switch(flags | SWT_REMOTEPREEMPT, NULL);
2157  }
2158  thread_unlock(td);
2159 }
2160 
2161 /*
2162  * Fix priorities on return to user-space. Priorities may be elevated due
2163  * to static priorities in msleep() or similar.
2164  */
2165 void
2166 sched_userret(struct thread *td)
2167 {
2168  /*
2169  * XXX we cheat slightly on the locking here to avoid locking in
2170  * the usual case. Setting td_priority here is essentially an
2171  * incomplete workaround for not setting it properly elsewhere.
2172  * Now that some interrupt handlers are threads, not setting it
2173  * properly elsewhere can clobber it in the window between setting
2174  * it here and returning to user mode, so don't waste time setting
2175  * it perfectly here.
2176  */
2177  KASSERT((td->td_flags & TDF_BORROWING) == 0,
2178  ("thread with borrowed priority returning to userland"));
2179  if (td->td_priority != td->td_user_pri) {
2180  thread_lock(td);
2181  td->td_priority = td->td_user_pri;
2182  td->td_base_pri = td->td_user_pri;
2183  tdq_setlowpri(TDQ_SELF(), td);
2184  thread_unlock(td);
2185  }
2186 }
2187 
2188 /*
2189  * Handle a stathz tick. This is really only relevant for timeshare
2190  * threads.
2191  */
2192 void
2193 sched_clock(struct thread *td)
2194 {
2195  struct tdq *tdq;
2196  struct td_sched *ts;
2197 
2198  THREAD_LOCK_ASSERT(td, MA_OWNED);
2199  tdq = TDQ_SELF();
2200 #ifdef SMP
2201  /*
2202  * We run the long term load balancer infrequently on the first cpu.
2203  */
2204  if (balance_tdq == tdq) {
2205  if (balance_ticks && --balance_ticks == 0)
2206  sched_balance();
2207  }
2208 #endif
2209  /*
2210  * Save the old switch count so we have a record of the last ticks
2211  * activity. Initialize the new switch count based on our load.
2212  * If there is some activity seed it to reflect that.
2213  */
2214  tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt;
2215  tdq->tdq_switchcnt = tdq->tdq_load;
2216  /*
2217  * Advance the insert index once for each tick to ensure that all
2218  * threads get a chance to run.
2219  */
2220  if (tdq->tdq_idx == tdq->tdq_ridx) {
2221  tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS;
2222  if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx]))
2223  tdq->tdq_ridx = tdq->tdq_idx;
2224  }
2225  ts = td->td_sched;
2226  sched_pctcpu_update(ts, 1);
2227  if (td->td_pri_class & PRI_FIFO_BIT)
2228  return;
2229  if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) {
2230  /*
2231  * We used a tick; charge it to the thread so
2232  * that we can compute our interactivity.
2233  */
2234  td->td_sched->ts_runtime += tickincr;
2236  sched_priority(td);
2237  }
2238 
2239  /*
2240  * Force a context switch if the current thread has used up a full
2241  * time slice (default is 100ms).
2242  */
2243  if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) {
2244  ts->ts_slice = 0;
2245  td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND;
2246  }
2247 }
2248 
2249 /*
2250  * Called once per hz tick.
2251  */
2252 void
2253 sched_tick(int cnt)
2254 {
2255 
2256 }
2257 
2258 /*
2259  * Return whether the current CPU has runnable tasks. Used for in-kernel
2260  * cooperative idle threads.
2261  */
2262 int
2264 {
2265  struct tdq *tdq;
2266  int load;
2267 
2268  load = 1;
2269 
2270  tdq = TDQ_SELF();
2271  if ((curthread->td_flags & TDF_IDLETD) != 0) {
2272  if (tdq->tdq_load > 0)
2273  goto out;
2274  } else
2275  if (tdq->tdq_load - 1 > 0)
2276  goto out;
2277  load = 0;
2278 out:
2279  return (load);
2280 }
2281 
2282 /*
2283  * Choose the highest priority thread to run. The thread is removed from
2284  * the run-queue while running however the load remains. For SMP we set
2285  * the tdq in the global idle bitmask if it idles here.
2286  */
2287 struct thread *
2289 {
2290  struct thread *td;
2291  struct tdq *tdq;
2292 
2293  tdq = TDQ_SELF();
2294  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2295  td = tdq_choose(tdq);
2296  if (td) {
2297  tdq_runq_rem(tdq, td);
2298  tdq->tdq_lowpri = td->td_priority;
2299  return (td);
2300  }
2301  tdq->tdq_lowpri = PRI_MAX_IDLE;
2302  return (PCPU_GET(idlethread));
2303 }
2304 
2305 /*
2306  * Set owepreempt if necessary. Preemption never happens directly in ULE,
2307  * we always request it once we exit a critical section.
2308  */
2309 static inline void
2310 sched_setpreempt(struct thread *td)
2311 {
2312  struct thread *ctd;
2313  int cpri;
2314  int pri;
2315 
2316  THREAD_LOCK_ASSERT(curthread, MA_OWNED);
2317 
2318  ctd = curthread;
2319  pri = td->td_priority;
2320  cpri = ctd->td_priority;
2321  if (pri < cpri)
2322  ctd->td_flags |= TDF_NEEDRESCHED;
2323  if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd))
2324  return;
2325  if (!sched_shouldpreempt(pri, cpri, 0))
2326  return;
2327  ctd->td_owepreempt = 1;
2328 }
2329 
2330 /*
2331  * Add a thread to a thread queue. Select the appropriate runq and add the
2332  * thread to it. This is the internal function called when the tdq is
2333  * predetermined.
2334  */
2335 void
2336 tdq_add(struct tdq *tdq, struct thread *td, int flags)
2337 {
2338 
2339  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2340  KASSERT((td->td_inhibitors == 0),
2341  ("sched_add: trying to run inhibited thread"));
2342  KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
2343  ("sched_add: bad thread state"));
2344  KASSERT(td->td_flags & TDF_INMEM,
2345  ("sched_add: thread swapped out"));
2346 
2347  if (td->td_priority < tdq->tdq_lowpri)
2348  tdq->tdq_lowpri = td->td_priority;
2349  tdq_runq_add(tdq, td, flags);
2350  tdq_load_add(tdq, td);
2351 }
2352 
2353 /*
2354  * Select the target thread queue and add a thread to it. Request
2355  * preemption or IPI a remote processor if required.
2356  */
2357 void
2358 sched_add(struct thread *td, int flags)
2359 {
2360  struct tdq *tdq;
2361 #ifdef SMP
2362  int cpu;
2363 #endif
2364 
2365  KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
2366  "prio:%d", td->td_priority, KTR_ATTR_LINKED,
2367  sched_tdname(curthread));
2368  KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
2369  KTR_ATTR_LINKED, sched_tdname(td));
2370  SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
2371  flags & SRQ_PREEMPTED);
2372  THREAD_LOCK_ASSERT(td, MA_OWNED);
2373  /*
2374  * Recalculate the priority before we select the target cpu or
2375  * run-queue.
2376  */
2377  if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
2378  sched_priority(td);
2379 #ifdef SMP
2380  /*
2381  * Pick the destination cpu and if it isn't ours transfer to the
2382  * target cpu.
2383  */
2384  cpu = sched_pickcpu(td, flags);
2385  tdq = sched_setcpu(td, cpu, flags);
2386  tdq_add(tdq, td, flags);
2387  if (cpu != PCPU_GET(cpuid)) {
2388  tdq_notify(tdq, td);
2389  return;
2390  }
2391 #else
2392  tdq = TDQ_SELF();
2393  TDQ_LOCK(tdq);
2394  /*
2395  * Now that the thread is moving to the run-queue, set the lock
2396  * to the scheduler's lock.
2397  */
2398  thread_lock_set(td, TDQ_LOCKPTR(tdq));
2399  tdq_add(tdq, td, flags);
2400 #endif
2401  if (!(flags & SRQ_YIELDING))
2402  sched_setpreempt(td);
2403 }
2404 
2405 /*
2406  * Remove a thread from a run-queue without running it. This is used
2407  * when we're stealing a thread from a remote queue. Otherwise all threads
2408  * exit by calling sched_exit_thread() and sched_throw() themselves.
2409  */
2410 void
2411 sched_rem(struct thread *td)
2412 {
2413  struct tdq *tdq;
2414 
2415  KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem",
2416  "prio:%d", td->td_priority);
2417  SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL);
2418  tdq = TDQ_CPU(td->td_sched->ts_cpu);
2419  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2420  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2421  KASSERT(TD_ON_RUNQ(td),
2422  ("sched_rem: thread not on run queue"));
2423  tdq_runq_rem(tdq, td);
2424  tdq_load_rem(tdq, td);
2425  TD_SET_CAN_RUN(td);
2426  if (td->td_priority == tdq->tdq_lowpri)
2427  tdq_setlowpri(tdq, NULL);
2428 }
2429 
2430 /*
2431  * Fetch cpu utilization information. Updates on demand.
2432  */
2433 fixpt_t
2434 sched_pctcpu(struct thread *td)
2435 {
2436  fixpt_t pctcpu;
2437  struct td_sched *ts;
2438 
2439  pctcpu = 0;
2440  ts = td->td_sched;
2441  if (ts == NULL)
2442  return (0);
2443 
2444  THREAD_LOCK_ASSERT(td, MA_OWNED);
2445  sched_pctcpu_update(ts, TD_IS_RUNNING(td));
2446  if (ts->ts_ticks) {
2447  int rtick;
2448 
2449  /* How many rtick per second ? */
2450  rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz);
2451  pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT;
2452  }
2453 
2454  return (pctcpu);
2455 }
2456 
2457 /*
2458  * Enforce affinity settings for a thread. Called after adjustments to
2459  * cpumask.
2460  */
2461 void
2462 sched_affinity(struct thread *td)
2463 {
2464 #ifdef SMP
2465  struct td_sched *ts;
2466 
2467  THREAD_LOCK_ASSERT(td, MA_OWNED);
2468  ts = td->td_sched;
2469  if (THREAD_CAN_SCHED(td, ts->ts_cpu))
2470  return;
2471  if (TD_ON_RUNQ(td)) {
2472  sched_rem(td);
2473  sched_add(td, SRQ_BORING);
2474  return;
2475  }
2476  if (!TD_IS_RUNNING(td))
2477  return;
2478  /*
2479  * Force a switch before returning to userspace. If the
2480  * target thread is not running locally send an ipi to force
2481  * the issue.
2482  */
2483  td->td_flags |= TDF_NEEDRESCHED;
2484  if (td != curthread)
2485  ipi_cpu(ts->ts_cpu, IPI_PREEMPT);
2486 #endif
2487 }
2488 
2489 /*
2490  * Bind a thread to a target cpu.
2491  */
2492 void
2493 sched_bind(struct thread *td, int cpu)
2494 {
2495  struct td_sched *ts;
2496 
2497  THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED);
2498  KASSERT(td == curthread, ("sched_bind: can only bind curthread"));
2499  ts = td->td_sched;
2500  if (ts->ts_flags & TSF_BOUND)
2501  sched_unbind(td);
2502  KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td));
2503  ts->ts_flags |= TSF_BOUND;
2504  sched_pin();
2505  if (PCPU_GET(cpuid) == cpu)
2506  return;
2507  ts->ts_cpu = cpu;
2508  /* When we return from mi_switch we'll be on the correct cpu. */
2509  mi_switch(SW_VOL, NULL);
2510 }
2511 
2512 /*
2513  * Release a bound thread.
2514  */
2515 void
2516 sched_unbind(struct thread *td)
2517 {
2518  struct td_sched *ts;
2519 
2520  THREAD_LOCK_ASSERT(td, MA_OWNED);
2521  KASSERT(td == curthread, ("sched_unbind: can only bind curthread"));
2522  ts = td->td_sched;
2523  if ((ts->ts_flags & TSF_BOUND) == 0)
2524  return;
2525  ts->ts_flags &= ~TSF_BOUND;
2526  sched_unpin();
2527 }
2528 
2529 int
2530 sched_is_bound(struct thread *td)
2531 {
2532  THREAD_LOCK_ASSERT(td, MA_OWNED);
2533  return (td->td_sched->ts_flags & TSF_BOUND);
2534 }
2535 
2536 /*
2537  * Basic yield call.
2538  */
2539 void
2540 sched_relinquish(struct thread *td)
2541 {
2542  thread_lock(td);
2543  mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
2544  thread_unlock(td);
2545 }
2546 
2547 /*
2548  * Return the total system load.
2549  */
2550 int
2552 {
2553 #ifdef SMP
2554  int total;
2555  int i;
2556 
2557  total = 0;
2558  CPU_FOREACH(i)
2559  total += TDQ_CPU(i)->tdq_sysload;
2560  return (total);
2561 #else
2562  return (TDQ_SELF()->tdq_sysload);
2563 #endif
2564 }
2565 
2566 int
2568 {
2569  return (sizeof(struct proc));
2570 }
2571 
2572 int
2574 {
2575  return (sizeof(struct thread) + sizeof(struct td_sched));
2576 }
2577 
2578 #ifdef SMP
2579 #define TDQ_IDLESPIN(tdq) \
2580  ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0)
2581 #else
2582 #define TDQ_IDLESPIN(tdq) 1
2583 #endif
2584 
2585 /*
2586  * The actual idle process.
2587  */
2588 void
2590 {
2591  struct thread *td;
2592  struct tdq *tdq;
2593  int oldswitchcnt, switchcnt;
2594  int i;
2595 
2596  mtx_assert(&Giant, MA_NOTOWNED);
2597  td = curthread;
2598  tdq = TDQ_SELF();
2599  THREAD_NO_SLEEPING();
2600  oldswitchcnt = -1;
2601  for (;;) {
2602  if (tdq->tdq_load) {
2603  thread_lock(td);
2604  mi_switch(SW_VOL | SWT_IDLE, NULL);
2605  thread_unlock(td);
2606  }
2607  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2608 #ifdef SMP
2609  if (switchcnt != oldswitchcnt) {
2610  oldswitchcnt = switchcnt;
2611  if (tdq_idled(tdq) == 0)
2612  continue;
2613  }
2614  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2615 #else
2616  oldswitchcnt = switchcnt;
2617 #endif
2618  /*
2619  * If we're switching very frequently, spin while checking
2620  * for load rather than entering a low power state that
2621  * may require an IPI. However, don't do any busy
2622  * loops while on SMT machines as this simply steals
2623  * cycles from cores doing useful work.
2624  */
2625  if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) {
2626  for (i = 0; i < sched_idlespins; i++) {
2627  if (tdq->tdq_load)
2628  break;
2629  cpu_spinwait();
2630  }
2631  }
2632 
2633  /* If there was context switch during spin, restart it. */
2634  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2635  if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt)
2636  continue;
2637 
2638  /* Run main MD idle handler. */
2639  tdq->tdq_cpu_idle = 1;
2640  cpu_idle(switchcnt * 4 > sched_idlespinthresh);
2641  tdq->tdq_cpu_idle = 0;
2642 
2643  /*
2644  * Account thread-less hardware interrupts and
2645  * other wakeup reasons equal to context switches.
2646  */
2647  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2648  if (switchcnt != oldswitchcnt)
2649  continue;
2650  tdq->tdq_switchcnt++;
2651  oldswitchcnt++;
2652  }
2653 }
2654 
2655 /*
2656  * A CPU is entering for the first time or a thread is exiting.
2657  */
2658 void
2659 sched_throw(struct thread *td)
2660 {
2661  struct thread *newtd;
2662  struct tdq *tdq;
2663 
2664  tdq = TDQ_SELF();
2665  if (td == NULL) {
2666  /* Correct spinlock nesting and acquire the correct lock. */
2667  TDQ_LOCK(tdq);
2668  spinlock_exit();
2669  PCPU_SET(switchtime, cpu_ticks());
2670  PCPU_SET(switchticks, ticks);
2671  } else {
2672  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2673  tdq_load_rem(tdq, td);
2674  lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object);
2675  }
2676  KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
2677  newtd = choosethread();
2678  TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd;
2679  cpu_throw(td, newtd); /* doesn't return */
2680 }
2681 
2682 /*
2683  * This is called from fork_exit(). Just acquire the correct locks and
2684  * let fork do the rest of the work.
2685  */
2686 void
2687 sched_fork_exit(struct thread *td)
2688 {
2689  struct td_sched *ts;
2690  struct tdq *tdq;
2691  int cpuid;
2692 
2693  /*
2694  * Finish setting up thread glue so that it begins execution in a
2695  * non-nested critical section with the scheduler lock held.
2696  */
2697  cpuid = PCPU_GET(cpuid);
2698  tdq = TDQ_CPU(cpuid);
2699  ts = td->td_sched;
2700  if (TD_IS_IDLETHREAD(td))
2701  td->td_lock = TDQ_LOCKPTR(tdq);
2702  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2703  td->td_oncpu = cpuid;
2704  TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED);
2705  lock_profile_obtain_lock_success(
2706  &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__);
2707 }
2708 
2709 /*
2710  * Create on first use to catch odd startup conditons.
2711  */
2712 char *
2713 sched_tdname(struct thread *td)
2714 {
2715 #ifdef KTR
2716  struct td_sched *ts;
2717 
2718  ts = td->td_sched;
2719  if (ts->ts_name[0] == '\0')
2720  snprintf(ts->ts_name, sizeof(ts->ts_name),
2721  "%s tid %d", td->td_name, td->td_tid);
2722  return (ts->ts_name);
2723 #else
2724  return (td->td_name);
2725 #endif
2726 }
2727 
2728 #ifdef KTR
2729 void
2730 sched_clear_tdname(struct thread *td)
2731 {
2732  struct td_sched *ts;
2733 
2734  ts = td->td_sched;
2735  ts->ts_name[0] = '\0';
2736 }
2737 #endif
2738 
2739 #ifdef SMP
2740 
2741 /*
2742  * Build the CPU topology dump string. Is recursively called to collect
2743  * the topology tree.
2744  */
2745 static int
2746 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg,
2747  int indent)
2748 {
2749  char cpusetbuf[CPUSETBUFSIZ];
2750  int i, first;
2751 
2752  sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent,
2753  "", 1 + indent / 2, cg->cg_level);
2754  sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "",
2755  cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask));
2756  first = TRUE;
2757  for (i = 0; i < MAXCPU; i++) {
2758  if (CPU_ISSET(i, &cg->cg_mask)) {
2759  if (!first)
2760  sbuf_printf(sb, ", ");
2761  else
2762  first = FALSE;
2763  sbuf_printf(sb, "%d", i);
2764  }
2765  }
2766  sbuf_printf(sb, "</cpu>\n");
2767 
2768  if (cg->cg_flags != 0) {
2769  sbuf_printf(sb, "%*s <flags>", indent, "");
2770  if ((cg->cg_flags & CG_FLAG_HTT) != 0)
2771  sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>");
2772  if ((cg->cg_flags & CG_FLAG_THREAD) != 0)
2773  sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>");
2774  if ((cg->cg_flags & CG_FLAG_SMT) != 0)
2775  sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>");
2776  sbuf_printf(sb, "</flags>\n");
2777  }
2778 
2779  if (cg->cg_children > 0) {
2780  sbuf_printf(sb, "%*s <children>\n", indent, "");
2781  for (i = 0; i < cg->cg_children; i++)
2782  sysctl_kern_sched_topology_spec_internal(sb,
2783  &cg->cg_child[i], indent+2);
2784  sbuf_printf(sb, "%*s </children>\n", indent, "");
2785  }
2786  sbuf_printf(sb, "%*s</group>\n", indent, "");
2787  return (0);
2788 }
2789 
2790 /*
2791  * Sysctl handler for retrieving topology dump. It's a wrapper for
2792  * the recursive sysctl_kern_smp_topology_spec_internal().
2793  */
2794 static int
2795 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS)
2796 {
2797  struct sbuf *topo;
2798  int err;
2799 
2800  KASSERT(cpu_top != NULL, ("cpu_top isn't initialized"));
2801 
2802  topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND);
2803  if (topo == NULL)
2804  return (ENOMEM);
2805 
2806  sbuf_printf(topo, "<groups>\n");
2807  err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1);
2808  sbuf_printf(topo, "</groups>\n");
2809 
2810  if (err == 0) {
2811  sbuf_finish(topo);
2812  err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo));
2813  }
2814  sbuf_delete(topo);
2815  return (err);
2816 }
2817 
2818 #endif
2819 
2820 static int
2821 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
2822 {
2823  int error, new_val, period;
2824 
2825  period = 1000000 / realstathz;
2826  new_val = period * sched_slice;
2827  error = sysctl_handle_int(oidp, &new_val, 0, req);
2828  if (error != 0 || req->newptr == NULL)
2829  return (error);
2830  if (new_val <= 0)
2831  return (EINVAL);
2832  sched_slice = imax(1, (new_val + period / 2) / period);
2833  sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR;
2834  hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
2835  realstathz);
2836  return (0);
2837 }
2838 
2839 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler");
2840 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0,
2841  "Scheduler name");
2842 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW,
2843  NULL, 0, sysctl_kern_quantum, "I",
2844  "Quantum for timeshare threads in microseconds");
2845 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
2846  "Quantum for timeshare threads in stathz ticks");
2847 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0,
2848  "Interactivity score threshold");
2849 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW,
2850  &preempt_thresh, 0,
2851  "Maximal (lowest) priority for preemption");
2852 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0,
2853  "Assign static kernel priorities to sleeping threads");
2854 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0,
2855  "Number of times idle thread will spin waiting for new work");
2856 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW,
2858  "Threshold before we will permit idle thread spinning");
2859 #ifdef SMP
2860 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0,
2861  "Number of hz ticks to keep thread affinity for");
2862 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0,
2863  "Enables the long-term load balancer");
2864 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW,
2865  &balance_interval, 0,
2866  "Average period in stathz ticks to run the long-term balancer");
2867 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0,
2868  "Attempts to steal work from other cores before idling");
2869 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0,
2870  "Minimum load on remote CPU before we'll steal");
2871 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING |
2872  CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A",
2873  "XML dump of detected CPU topology");
2874 #endif
2875 
2876 /* ps compat. All cpu percentages from ULE are weighted. */
2877 static int ccpu = 0;
2878 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");