linux-kernel - Re: [REPORT] cfs-v4 vs sd-0.44

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Date:	Tue, 24 Apr 2007 08:08:56 -0700
From:	"Ray Lee" <madrabbit@...il.com>
To:	"Linus Torvalds" <torvalds@...ux-foundation.org>
Cc:	"Ingo Molnar" <mingo@...e.hu>, "Nick Piggin" <npiggin@...e.de>,
	"Juliusz Chroboczek" <jch@....jussieu.fr>,
	"Con Kolivas" <kernel@...ivas.org>, "ck list" <ck@....kolivas.org>,
	"Bill Davidsen" <davidsen@....com>, "Willy Tarreau" <w@....eu>,
	"William Lee Irwin III" <wli@...omorphy.com>,
	linux-kernel@...r.kernel.org,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Mike Galbraith" <efault@....de>,
	"Arjan van de Ven" <arjan@...radead.org>,
	"Peter Williams" <pwil3058@...pond.net.au>,
	"Thomas Gleixner" <tglx@...utronix.de>, caglar@...dus.org.tr,
	"Gene Heskett" <gene.heskett@...il.com>
Subject: Re: [REPORT] cfs-v4 vs sd-0.44

On 4/23/07, Linus Torvalds <torvalds@...ux-foundation.org> wrote:
> On Mon, 23 Apr 2007, Ingo Molnar wrote:
> >
> > The "give scheduler money" transaction can be both an "implicit
> > transaction" (for example when writing to UNIX domain sockets or
> > blocking on a pipe, etc.), or it could be an "explicit transaction":
> > sched_yield_to(). This latter i've already implemented for CFS, but it's
> > much less useful than the really significant implicit ones, the ones
> > which will help X.
>
> Yes. It would be wonderful to get it working automatically, so please say
> something about the implementation..
>
> The "perfect" situation would be that when somebody goes to sleep, any
> extra points it had could be given to whoever it woke up last. Note that
> for something like X, it means that the points are 100% ephemeral: it gets
> points when a client sends it a request, but it would *lose* the points
> again when it sends the reply!

It would seem like there should be a penalty associated with sending
those points as well, so that two processes communicating quickly with
each other won't get into a mutual love-fest that'll capture the
scheduler's attention.

Ray
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