Re: [patch 2/2] sched: fix select_idle_sibling() logic inselect_task_rq_fair()

From: Mike Galbraith
Date: Tue Mar 09 2010 - 01:06:14 EST


On Mon, 2010-03-08 at 14:24 -0800, Suresh Siddha wrote:
> On Fri, 2010-03-05 at 12:25 -0800, Mike Galbraith wrote:
> > On Fri, 2010-03-05 at 10:39 -0800, Suresh Siddha wrote:
> > > plain text document attachment (fix_lat_ctx.patch)
> > > Performance improvements with this patch:
> > > "lat_ctx -s 0 2" ~22usec (before-this-patch) ~5usec (after-this-patch)
> >
> > Hm. On my Q6600 box, it's nowhere near that.
>
> My numbers are based on an atom netbook.

Wish I had an atom to play with, hard to even imagine 22 usec lat_ctx,
that's some _serious_ pain.

> > Calling the waking cpu idle in that case is a mistake. Just because the
> > sync hint was used does not mean there is no gain to be had.
>
> Ok. I dropped that part in v2 patches that I just posted.

Yeah, I see mails (ramble ramble) crossed in the night. I'll take them
out for a spin, see if your box can get fixed up without busting mine :)

-Mike

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