- script to check internal locks
- script to trace futexes
- script to generate stats for DTracified linuxulator parts
- script to check for errors:
The programming-error checks give hints about userland programming errors respectively a hint about the reason of error return values due to resource shortage or maybe a wrong combination of parameters. An example error message for this case is “Application %s issued a sysctl which failed the length restrictions.\nThe length passed is %d, the min length supported is 1 and the max length supported is %d.\n”.
The stats-script (tailored specially to the linuxulator, but this can easily be extended to the rest of the kernel) can report about:
- number of calls to a kernel function per executable binary (not per PID!): allows to see where an optimization would be beneficial for a given application
- graph of CPU time spend in kernel functions per executable binary: together with the number of calls to this function this allows to determine if a kernel optimization would be beneficial / is possible for a given application
- graph of longest running (CPU-time!) kernel function in total
- timing statistics for the emul_lock
- graph of longest held (CPU-time!) locks
Unfortunately this can not be committed to HEAD as-is. The DTrace SDT provider can not handle probes which are added to the kernel after the SDT provider is already loaded. This means that you either have to compile the linuxulator statically into the kernel, or you have to load the SDT kernel module after the linuxulator module is loaded. If you do not respect this, you get a kernel panic on first access of one of the providers in the linuxulator (AFAIR this includes listing the probes available in the kernel).
Tags: error checks, error return, example error, kernel function, kernel functions, length restrictions, programming error, programming errors, time kernel, timing statistics —