To:	linux-kernel@vger.rutgers.edu
Subject: [PATCH] per-process RSS limits (was: Re: Process Aggregates: module based support for jobs)
From:	Peter Chubb <peterc@aurema.com>
Date:	23 Jun 2000 08:54:24 +1000


Hi Everyone,
   As a first step toward RSS limits/guarantees, we've been working on 
making the setrlimit(RLIMIT_RSS,...) call work.  The 12k patch at

ftp://ftp-au.aurema.com/private/aurpjc31/linux-2216-rsslimit.diff.bz2

tracks integral and maximum RSS and makes them available to the
getrusage() and wait4() system calls (so /usr/bin/time -v reports
something meaningful), and adds three new CONFIG_EXPERIMENTAL options
to an otherwise stock Linux  2.2.16.  These are:
CONFIG_PROC_RSS
	Adds to /proc a file in each process's directory
	/proc/<pid>/rss 
	which allows control of RSS limits, and monitoring of minor
	and major page fault rates.

	We use this primarily to test the other two options:

CONFIG_RSS_HARDLIMIT
	causes any process that is over its limit to release a page
	every time it tries to grab a page.

CONFIG_RSS_SOFTLIMIT
	creates a new daemon, krssd, that every second scans all
	address spaces looking for ones over their limit, and attempts 
	to shrink each until under limit again.

It shouldn't be too hard to port the patch to 2.4.0-xxx or
2.5 when it gets going.

When no processes are over limit, there's no obvious difference in
overhead -- it's down in the noise (on my machines, there's more
difference in successive runs of make -j4 clean; make -j4 bzImage on
the same kernel than there is between the average of ten runs with and 
without the patch)

Share and Enjoy!
	
-- 
Dr Peter Chubb, Vice-President, Research
Aurema Pty Ltd,  P.O. Box 305,  Strawberry Hills, NSW 2012, AUSTRALIA
Phone: +61 2 9698 2322;    Fax: +61 2 9699 9174;    peterc@aurema.com

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