linux-kernel - Re: [patch] sched: fix broken smt/mc optimizations with CFS

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Message-ID: <20070827193103.GF1894@linux-os.sc.intel.com>
Date:	Mon, 27 Aug 2007 12:31:03 -0700
From:	"Siddha, Suresh B" <suresh.b.siddha@...el.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	"Siddha, Suresh B" <suresh.b.siddha@...el.com>,
	nickpiggin@...oo.com.au, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org
Subject: Re: [patch] sched: fix broken smt/mc optimizations with CFS

On Mon, Aug 27, 2007 at 09:23:24PM +0200, Ingo Molnar wrote:
> 
> * Siddha, Suresh B <suresh.b.siddha@...el.com> wrote:
> 
> > > -	if (*imbalance + SCHED_LOAD_SCALE_FUZZ < busiest_load_per_task/2) {
> > > +	if (*imbalance + SCHED_LOAD_SCALE_FUZZ < busiest_load_per_task) {
> > 
> > Ingo, this is still broken. This condition is always false for nice-0 
> > tasks..
> 
> yes - negative reniced tasks are not spread out via this - and positive 
> reniced tasks are spread out more easily.

Or the opposite?

Essentially I observed that nice 0 tasks still endup on two cores of same
package, with out getting spread out to two different packages. This behavior
is same with out this fix and this fix doesn't help in any way.

thanks,
suresh
-
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