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Date: Mon, 16 Jul 2007 13:20:37 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Roman Zippel <zippel@linux-m68k.org>
Cc: James Bruce <bruce@andrew.cmu.edu>, Thomas Gleixner <tglx@linutronix.de>,
       Mike Galbraith <efault@gmx.de>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Andrea Arcangeli <andrea@suse.de>, Andi Kleen <andi@firstfloor.org>,
       Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org,
       Arjan van de Ven <arjan@infradead.org>,
       Chris Wright <chrisw@sous-sol.org>
Subject: Re: [PATCH] CFS: Fix missing digit off in wmult table
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* Roman Zippel <zippel@linux-m68k.org> wrote:

> > yes, the weight multiplier 1.25, but the actual difference in CPU 
> > utilization, when running two CPU intense tasks, is ~10%:
> > 
> >   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> >  8246 mingo     20   0  1576  244  196 R   55  0.0   0:11.96 loop
> >  8247 mingo     21   1  1576  244  196 R   45  0.0   0:10.52 loop
> > 
> > so the first task 'wins' +10% CPU utilization (relative to the 50% 
> > it had before), the second task 'loses' -10% CPU utilization 
> > (relative to the 50% it had before).
> 
> As soon as you add another loop the difference changes again, while 
> it's always correct to say it gets 25% more cpu time [...]

yep, and i'll add the relative effect to the comment too.

	Ingo