Date: Fri, 11 Feb 2005 10:04:19 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Matt Mackall <mpm@selenic.com>
Cc: Paul Davis <paul@linuxaudiosystems.com>,
       Peter Williams <pwil3058@bigpond.net.au>,
       Nick Piggin <nickpiggin@yahoo.com.au>, Chris Wright <chrisw@osdl.org>,
       "Jack O'Quin" <jack.oquin@gmail.com>, Andrew Morton <akpm@osdl.org>,
       Christoph Hellwig <hch@infradead.org>, linux-kernel@vger.kernel.org,
       Con Kolivas <kernel@kolivas.org>, rlrevell@joe-job.com
Subject: Re: 2.6.11-rc3-mm2
Message-ID: <20050211090419.GD3980@elte.hu>
References: <420C25D6.6090807@bigpond.net.au> <200502110341.j1B3fS8o017685@localhost.localdomain> <20050211065753.GE15058@waste.org> <20050211075417.GA2287@elte.hu> <20050211082536.GF15058@waste.org>
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* Matt Mackall <mpm@selenic.com> wrote:

> So the comparison boils down to putting a magic gid in a sysfs
> file/module parameter or setting an rlimit with standard tools (PAM,
> etc). I'm really boggled that anyone could prefer the former,
> especially since we had almost this exact debate over what became the
> mlock rlimit!

the big difference to mlock is that for mlock there _is_ a _limit_. For
RT scheduling the priority is _NOT_ a _limit_. Okay? So you give the
false pretense of this being some kind of resource 'limit', while in
fact allowing SCHED_FIFO prio 1 alone enables unprivileged users to lock
up the system.

so i could agree with RLIMIT_NICE (which _is_ a limit), but
RLIMIT_RTPRIO sends the wrong message. The proper rlimit would be
RLIMIT_RT_CPU (the patch i did).

	Ingo
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