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Subject: Re: Scheduler priorities
From: Robert Love <rml@tech9.net>
To: Pavel Machek <pavel@ucw.cz>
Cc: Wessel Dankers <wsl@fruit.eu.org>, linux-kernel@vger.kernel.org
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Date: 29 Mar 2002 18:52:21 -0500
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On Fri, 2002-03-29 at 16:42, Pavel Machek wrote:

> On each entry of kernel, promote SCHED_IDLE task to SCHED_NORMAL, and
> demote it at exit. This can be done with 0 overhad on hot paths.

Agreed.

> What's the problem with "promote at enter" approach? Using ptrace
> trick, it can be 0 overhead. [Was that your code that cleverly used
> ptrace?] What is problem with it?

There is no problem with the ptrace approach, it is good - I have
experimented with that solution myself.  There is just a lot more to
SCHED_IDLE than "make the task only run when nothing else wants to" and
even the ptrace solution may involve a bit of work.

	Robert Love

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