Re: [Announce] [patch] Modular Scheduler Core and Completely Fair Scheduler [CFS]

Ingo Molnar
2007-04-16T21:06:09Z

* Andi Kleen <andi@firstfloor.org> wrote:

> > i'm pleased to announce the first release of the "Modular Scheduler
> > Core and Completely Fair Scheduler [CFS]" patchset:
> >
> > http://redhat.com/~mingo/cfs-scheduler/sched-modular+cfs.patch
>
> I would suggest to drop the tsc.c change. The "small errors" can be
> really large on some systems and you can also see large backward
> jumps.

actually, i designed the CFS code assuming a per-CPU TSC (with no global
synchronization), not assuming any globally sync TSC. In fact i wrote it
on such systems: a CoreDuo2 box that has stops the TSC in C3 and the
different cores have wildly different TSC values and a dual-core
Athlon64 that quickly drifts its TSC. So i'll keep the sched_clock()
change for now.

> BTW with all this CPU time measurement it would be really nice to
> report it to the user too. It seems a bit bizarre that the scheduler
> keeps track of ns, but top only knows jiffies with large sampling
> errors.

yeah - i'll fix that too if someone doesnt beat me at it.

Ingo