Re: [Bug #11308] tbench regression on each kernel release from 2.6.22 -> 2.6.28

Ingo Molnar
2008-11-17T19:53:16Z

* Linus Torvalds <torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org> wrote:

> On Mon, 17 Nov 2008, David Miller wrote:
> >
> > The scheduler has accounted for at least %10 of the tbench
> > regressions at this point, what are you talking about?
>
> I'm wondering if you're not looking at totally different issues.
>
> For example, if I recall correctly, David had a big hit on the
> hrtimers. And I wonder if perhaps Ingo's numbers are without
> hrtimers or something?

hrtimers should not be an issue anymore since this commit:

| commit 0c4b83da58ec2e96ce9c44c211d6eac5f9dae478
| Author: Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>
| Date: Mon Oct 20 14:27:43 2008 +0200
|
| sched: disable the hrtick for now
|
| David Miller reported that hrtick update overhead has tripled the
| wakeup overhead on Sparc64.
|
| That is too much - disable the HRTICK feature for now by default,
| until a faster implementation is found.
|
| Reported-by: David Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
| Acked-by: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
| Signed-off-by: Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>

Which was included in v2.6.28-rc1 already.

Ingo