Re: [RFC][PATCH] Multimedia scheduling class, take 2

From: Jussi Laako <jussi@sonarnerd.net>
To: Chris Friesen <cfriesen@nortel.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	James Courtier-Dutton <James@superbug.co.uk>,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
	d.faggioli@sssup.it
Subject: Re: [RFC][PATCH] Multimedia scheduling class, take 2
Date: Tue, 12 May 2009 20:53:37 +0300	[thread overview]
Message-ID: <4A09B7A1.2060706@sonarnerd.net> (raw)
In-Reply-To: <4A09AB2E.8030002@nortel.com>

Chris Friesen wrote:
> Of course, without glibc/pthreads support you would only be able to set
> the nice level for the current thread since you don't have any way to
> map from "pthread_t *" to tid.  And you wouldn't be able to create new
> threads with a particular nice level already set.

This is the problem... It has to work this way, otherwise it's pretty
useless.

> But that argument
> holds true for a new sched policy as well, because glibc checks the
> policy internally and only knows about the normal three.

Don't tell that to my system, where also SCHED_IDLE, SCHED_BATCH (which
are btw not listed on POSIX either) ...and... SCHED_MM work. It goes
directly to kernel which does the checks and fails if it sees fit.

> This option extends the "nice" API rather than the static priority API,
> so all of the above would still have a static priority of 0 for SCHED_OTHER.

For extending "nice" API, I would first ask for extension in POSIX, and
once it's there I could think about implementation.

And still this doesn't solve the second level problem.

	- Jussi