Subject: Re: Rationale for RLIMIT_MEMLOCK?
From: Lee Revell <rlrevell@joe-job.com>
To: Matthias Andree <matthias.andree@gmx.de>
Cc: Arjan van de Ven <arjan@infradead.org>,
       Linux-Kernel mailing list <linux-kernel@vger.kernel.org>
In-Reply-To: <20060123185549.GA15985@merlin.emma.line.org>
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Date: Mon, 23 Jan 2006 14:57:34 -0500
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On Mon, 2006-01-23 at 19:55 +0100, Matthias Andree wrote:
> I'm asking the Bcc'd gentleman to reconsider mlockall() and perhaps
> use explicit mlock() instead. 

Probably good advice, I have found mlockall() to be especially
problematic with multithreaded programs and NPTL, as glibc eats
RLIMIT_STACK of unswappable memory for each thread stack which defaults
to 8MB here - you go OOM really quick like this.  Most people don't seem
to realize the need to set a sane value with pthread_attr_setstack().

(Even when not mlock'ed, insanely huge thread stack defaults seem to
account for a lot of the visible bloat on the desktop - decreasing
RLIMIT_STACK to 512KB reduces the footprint of Gnome 2.12 by 100+ MB.)

Lee

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