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Subject: Re: [PATCH] scheduler hints
From: Robert Love <rml@tech9.net>
To: Rick Bressler <rickb@mushroom.ca.boeing.com>
Cc: linux-kernel@vger.kernel.org
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Date: 05 Jun 2002 17:53:36 -0700
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On Wed, 2002-06-05 at 17:46, Rick Bressler wrote:

> Sequent had an interesting hint they cooked up with Oracle. (Or maybe it
> was the other way around.)  As I recall they called it 'twotask.'
> Essentially Oracle clients processes spend a lot of time exchanging
> information with its server process. It usually makes sense to bind them
> to the same CPU in an SMP (and especially NUMA) machine.  (Probably
> obvious to most of the folks on the group, but it is generally lots
> better to essentially communicate through the cache and local memory
> than across the NUMA bus.)

This is similar in theory to why we used to have the sync option on
wake_up for pipes... it does work.

We don't need a scheduler "hint" for this, though.  A big loud command
"bind me to this processor!" would do fine, and in 2.5 we have that:

just have one of the tasks do:

	sched_setaffinity(0, sizeof(unsigned long), 1);
	sched_setaffinity(other_guys_pid, sizeof(unsigned long), 1);

and both will be affined to CPU 1.

	Robert Love