Re: Dynamically determine if kernel includes CFS Scheduler

From: Peter Zijlstra
Date: Fri Mar 06 2009 - 16:01:20 EST


On Fri, 2009-03-06 at 12:44 -0800, Darren Hart wrote:
> I've received an internal request for a means to determine at run-time
> if the CFS scheduler is included in the running kernel. Looking through
> the git commit log and the /proc/sys/kernel filesystem, I think I see
> two approaches:
>
> 1) stat("/proc/sys/kernel/sched_compat_yield")
> This confirms 2.6.23-rc7 kernel or later which definitely has the CFS
> scheduler and this functionality is of interest anyway.
> 2) Test if the kernel version is >= 2.6.22 which is where I believe CFS
> landed.
>
> Any guesses as to how robust/future-proof approach #1 would be?

The question is why? Relying on scheduler specifics outside of whatever
POSIX mandates is an application bug.

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