Dynamically determine if kernel includes CFS Scheduler

[Darren Hart <dvhltc@us.ibm.com>]

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?

-- 
Darren Hart
IBM Linux Technology Center
Real-Time Linux Team