Date: Sat, 12 Jul 2003 19:51:57 +0100
From: Jamie Lokier <jamie@shareable.org>
To: Miguel Freitas <miguel@cetuc.puc-rio.br>
Cc: Davide Libenzi <davidel@xmailserver.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [patch] SCHED_SOFTRR linux scheduler policy ...
Message-ID: <20030712185157.GC10450@mail.jlokier.co.uk>
References: <1058017391.1197.24.camel@mf> <Pine.LNX.4.55.0307120735540.4351@bigblue.dev.mcafeelabs.com> <20030712154942.GB9547@mail.jlokier.co.uk> <Pine.LNX.4.55.0307120845470.4351@bigblue.dev.mcafeelabs.com> <20030712162029.GE9547@mail.jlokier.co.uk> <1058028064.1196.111.camel@mf>
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Miguel Freitas wrote:
> > I'm wondering what happens if the tasks are both good, early to bed
> > without a fuss.  Neither runs their entire timeslice.
> > 
> > Or to illustrate: say xine uses 10% of my CPU.  What happens when I
> > open 11 xine windows?
> 
> well of course 110% is more than what you have of resources and xine
> would have to drop frames to keep it up... :)

That's fine.  The problem is, does this completely starve the other
tasks such as kswapd, ksoftirqd, bash etc.?

The real problem is can a user accidentally or malicious lock up a box
using SCHED_SOFTRR (when xmms, xine, GNU software radio and modem are
all using it :), and also what about multi-user boxes, can two users
accidentally break it.

Perhaps there should be a _global_ maximum amount of CPU used in
SCHED_SOFTRR beyond which SCHED_SOFTRR tasks get downgraded.

-- Jamie
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