Re: [patch] SCHED_SOFTRR starve-free linux scheduling policy ...

From: Pavel Machek <pavel@ucw.cz>
To: Mike Galbraith <efault@gmx.de>
Cc: Roger Larsson <roger.larsson@skelleftea.mail.telia.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [patch] SCHED_SOFTRR starve-free linux scheduling policy ...
Date: Wed, 13 Aug 2003 01:35:02 +0200	[thread overview]
Message-ID: <20030812233502.GC1417@elf.ucw.cz> (raw)
In-Reply-To: <5.2.1.1.2.20030810084805.01a0dfa8@pop.gmx.net>

Hi!

> >> 2.   It's not useful for video (I see no difference between realtime
> >> component of video vs audio), and if the cpu restriction were opened up
> >> enough to become useful, you'd end up with ~pure SCHED_RR, which you can 
> >no
> >> way allow Joe User access to.  As a SCHED_LOWLATENCY, it seems like it
> >> might be useful, but I wonder how useful.
> >
> >Why shouldn't it be useful with video, is a frame processing burst longer 
> >than
> >a time slice? The rule for when to and how to revert a SCHED_SOFTRR can be
> >changed.
> 
> Everything I've seen says "you need at least a 300Mhz cpu to decode".  My 
> little cpu is 500Mhz, so I'd have to make more than half of my total 
> computational power available for SCHED_SOFTRR tasks for video decode in 
> realtime to work.  Even on my single user box, I wouldn't want to have to 
> fight for cpu because some random developer decided to use 
> SCHED_SOFTRR.  If I make that much cpu available, someone will try to use 
> it.  Personally, I think you should need authorization for even tiny 
> amounts of cpu at this priority.

What about only offering SCHED_SOFTRR to people logged in on console,
similar to way cdrom and /dev/dsp is handled on newer boxes?
								Pavel
-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]