linux-kernel - Re: [patch] Re: scheduler oddity [bug?]

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Message-Id: <1236607890.6168.7.camel@marge.simson.net>
Date:	Mon, 09 Mar 2009 15:11:30 +0100
From:	Mike Galbraith <efault@....de>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Ingo Molnar <mingo@...e.hu>, Balazs Scheidler <bazsi@...abit.hu>,
	linux-kernel@...r.kernel.org, Willy Tarreau <w@....eu>
Subject: Re: [patch] Re: scheduler oddity [bug?]

On Mon, 2009-03-09 at 14:58 +0100, Mike Galbraith wrote:
> On Mon, 2009-03-09 at 14:46 +0100, Peter Zijlstra wrote:
> > On Mon, 2009-03-09 at 14:37 +0100, Mike Galbraith wrote:
> > > On Mon, 2009-03-09 at 14:16 +0100, Mike Galbraith wrote:
> > > > On Mon, 2009-03-09 at 12:04 +0100, Peter Zijlstra wrote:
> > > > 
> > > > > OK, talked a bit with Ingo, the reason you're doing is that avg_overlap
> > > > > can easily grow stale.. I can see that happen indeed.
> > > > > 
> > > > > So the 'perfect' thing would be a task-runtime decay, barring that the
> > > > > preemption thing seems a sane enough hart-beat of a task.
> > > > > 
> > > > > How does the below look to you?
> > > > 
> > > > Other than the fact that the test for sync reject is currently
> > > > avg_overlap > sysctl_sched_migration_cost, looks fine to me.  Having it
> > > > capped at the boundary is probably the better way to go.
> > > 
> > > Heh, doesn't _quite_ work though.  The little bugger now hovers just
> > > under :-/
> > 
> > > se.avg_overlap                     :             0.499993
> > 
> > Right, update_avg()'s >>3 and the off-by-one you spotted.
> 
> (that was with the off-by-one fixed, but..)
> 
> > I recon stuff works better with a 2* added? After that I guess its
> > praying sysbench still works.. :-)
> 
> Yes 2* worked fine.  Mysql+oltp was my worry spot, being a very affinity
> sensitive little <bleep>, but my patchlet didn't cause any trouble, so
> this one shouldn't either.  I'll do some re-test in any case, and squeak
> should anything turn up.

Squeak!  Didn't even get to mysql+oltp.

marge:..local/tmp # netperf -t UDP_STREAM -l 60 -H 127.0.0.1  -- -P 15888,12384 -s 32768 -S 32768 -m 4096
UDP UNIDIRECTIONAL SEND TEST from 0.0.0.0 (0.0.0.0) port 15888 AF_INET to 127.0.0.1 (127.0.0.1) port 12384 AF_INET
Socket  Message  Elapsed      Messages
Size    Size     Time         Okay Errors   Throughput
bytes   bytes    secs            #      #   10^6bits/sec

 65536    4096   60.00     5161103      0    2818.65
 65536           60.00     5149666           2812.40

 6188 root      20   0  1040  544  324 R  100  0.0   0:31.49 0 netperf
 6189 root      20   0  1044  260  164 R   48  0.0   0:15.35 3 netserver

Hurt, pain, ouch, vs...

marge:..local/tmp # netperf -t UDP_STREAM -l 60 -H 127.0.0.1 -T 0,0 -- -P 15888,12384 -s 32768 -S 32768 -m 4096
UDP UNIDIRECTIONAL SEND TEST from 0.0.0.0 (0.0.0.0) port 15888 AF_INET to 127.0.0.1 (127.0.0.1) port 12384 AF_INET : cpu bind
Socket  Message  Elapsed      Messages
Size    Size     Time         Okay Errors   Throughput
bytes   bytes    secs            #      #   10^6bits/sec

 65536    4096   60.00     8452028      0    4615.93
 65536           60.00     8442945           4610.97

Drat.

	-Mike

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