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Message-ID: <462E990B.6000902@bigpond.net.au>
Date: Wed, 25 Apr 2007 09:55:55 +1000
From: Peter Williams <pwil3058@bigpond.net.au>
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To: Rogan Dawes <lists@dawes.za.net>
CC: Chris Friesen <cfriesen@nortel.com>, Ingo Molnar <mingo@elte.hu>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Nick Piggin <npiggin@suse.de>, Gene Heskett <gene.heskett@gmail.com>,
       Juliusz Chroboczek <jch@pps.jussieu.fr>, Mike Galbraith <efault@gmx.de>,
       linux-kernel@vger.kernel.org, ck list <ck@vds.kolivas.org>,
       Thomas Gleixner <tglx@linutronix.de>,
       William Lee Irwin III <wli@holomorphy.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Bill Davidsen <davidsen@tmr.com>, Willy Tarreau <w@1wt.eu>,
       Arjan van de Ven <arjan@infradead.org>
Subject: Re: [REPORT] cfs-v4 vs sd-0.44
References: <20070421160008.GA28783@elte.hu> <200704220959.34978.kernel@kolivas.org> <87647oblx5.fsf@pps.jussieu.fr> <alpine.LFD.0.98.0704221620310.9964@woody.linux-foundation.org> <20070423013429.GB25162@wotan.suse.de> <alpine.LFD.0.98.0704230844410.9964@woody.linux-foundation.org> <20070423191143.GA16849@elte.hu> <alpine.LFD.0.98.0704231227300.9964@woody.linux-foundation.org> <20070423203317.GA26668@elte.hu> <462DAC06.9040309@dawes.za.net> <20070424073103.GA29054@elte.hu> <462DBEF6.70205@dawes.za.net> <462E1C2E.30406@nortel.com> <462E1D37.3060008@dawes.za.net>
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Rogan Dawes wrote:
> Chris Friesen wrote:
>> Rogan Dawes wrote:
>>
>>> I guess my point was if we somehow get to an odd number of 
>>> nanoseconds, we'd end up with rounding errors. I'm not sure if your 
>>> algorithm will ever allow that.
>>
>> And Ingo's point was that when it takes thousands of nanoseconds for a 
>> single context switch, an error of half a nanosecond is down in the 
>> noise.
>>
>> Chris
> 
> My concern was that since Ingo said that this is a closed economy, with 
> a fixed sum/total, if we lose a nanosecond here and there, eventually 
> we'll lose them all.
> 
> Some folks have uptimes of multiple years.
> 
> Of course, I could (very likely!) be full of it! ;-)

And won't be using the any new scheduler on these computers anyhow as 
that would involve bringing the system down to install the new kernel. :-)

Peter
-- 
Peter Williams                                   pwil3058@bigpond.net.au

"Learning, n. The kind of ignorance distinguishing the studious."
  -- Ambrose Bierce