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From: Michael Gerdau <mgd@technosis.de>
To: Con Kolivas <kernel@kolivas.org>
Cc: ck@vds.kolivas.org, Ingo Molnar <mingo@elte.hu>,
	Nick Piggin <npiggin@suse.de>, Bill Davidsen <davidsen@tmr.com>,
	Juliusz Chroboczek <jch@pps.jussieu.fr>,
	Mike Galbraith <efault@gmx.de>,
	linux-kernel@vger.kernel.org,
	William Lee Irwin III <wli@holomorphy.com>,
	Peter Williams <pwil3058@bigpond.net.au>,
	Gene Heskett <gene.heskett@gmail.com>, Willy Tarreau <w@1wt.eu>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Arjan van de Ven <arjan@infradead.org>
Subject: Re: [ck] Re: [REPORT] cfs-v6-rc2 vs sd-0.46 vs 2.6.21-rc7
Date: Fri, 27 Apr 2007 07:59:07 +0200	[thread overview]
Message-ID: <200704270759.23265.mgd@technosis.de> (raw)
In-Reply-To: <200704270859.37931.kernel@kolivas.org>

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> Very interesting indeed but fairly complicated as well.

Sorry for that -- I've taken these figures from the 3MB logfile
that each job creates and "reading" them on a regular basis tend
to forget that probably everyody else does not find them as
obvious as I do. Also I'm don't really have lots of experience
with how a scheduler is properly tested.

For any upcoming tests I will restrict the numbers to wallclock
and what time provides which probably is better suited anyway.

> > as a summary: i think your numbers demonstrate it nicely that the
> > shorter 'timeslice length' that both CFS and SD utilizes does not have a
> > measurable negative impact on your workload. To measure the total impact
> > of 'timeslicing' you might want to try the exact same workload with a
> > much higher 'timeslice length' of say 400 msecs, via:
> >
> >     echo 400000000 > /proc/sys/kernel/sched_granularity_ns  # on CFS
> >     echo 400 > /proc/sys/kernel/rr_interval                 # on SD
> 
> I thought that the effective "timeslice" on CFS was double the 
> sched_granularity_ns so wouldn't this make the effective timeslice double 
> that of what you're setting SD to? Anyway the difference between 400 and 
> 800ms timeslices is unlikely to be significant so I don't mind.

I'm happy to do that, hopefully over the weekend.

Best,
Michael
-- 
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  reply	other threads:[~2007-04-27  6:53 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-26 11:12 Michael Gerdau
2007-04-26 12:07 ` Ingo Molnar
2007-04-26 13:22   ` Michael Gerdau
2007-04-26 13:55     ` Ingo Molnar
2007-04-26 22:59   ` [ck] " Con Kolivas
2007-04-27  5:59     ` Michael Gerdau [this message]
2007-04-27  6:52     ` Ingo Molnar

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