From mboxrd@z Thu Jan 1 00:00:00 1970 Message-Id: In-Reply-To: References: Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Date: Fri, 20 Apr 2001 13:02:11 +0100 From: Jonathan Morton Subject: Re: suspend processes at load (was Re: a simple OOM ...) Sender: owner-linux-mm@kvack.org Return-Path: To: Szabolcs Szakacsits , "James A. Sutherland" Cc: Dave McCracken , linux-mm@kvack.org List-ID: >> More to the point, though, what about the worst case, where every >> process is thrashing? > >What about the simplest case when one process thrasing? You suspend it >continuously from time to time so it won't finish e.g. in 10 minutes but >in 1 hour. One process thrashing, lots of other processes behaving sensibly. With the current page-replacement policy, active memory belonging to well-behaved processes will be regularly paged out (a Bad Thing?), whether the thrashing process is suspended periodically or not. The suspensions simply reduce the frequency of this a little. Where *every* process is thrashing, you have to suspend lots of processes in order to get the rest to run. Also, every time you change the set of suspended processes, you have to wait for the VM to settle before the peak useful work is being done again, and even longer than that before you can sensibly change the set of suspended processes again. This is *very* granular - of the order of tens of seconds for a medium-sized PC-type computer. We need a better page-replacement algorithm, and I think my suggestion goes some way towards that. Who knows, I might even attempt to implement it next week... -------------------------------------------------------------- from: Jonathan "Chromatix" Morton mail: chromi@cyberspace.org (not for attachments) big-mail: chromatix@penguinpowered.com uni-mail: j.d.morton@lancaster.ac.uk The key to knowledge is not to rely on people to teach you it. Get VNC Server for Macintosh from http://www.chromatix.uklinux.net/vnc/ -----BEGIN GEEK CODE BLOCK----- Version 3.12 GCS$/E/S dpu(!) s:- a20 C+++ UL++ P L+++ E W+ N- o? K? w--- O-- M++$ V? PS PE- Y+ PGP++ t- 5- X- R !tv b++ DI+++ D G e+ h+ r++ y+(*) -----END GEEK CODE BLOCK----- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux.eu.org/Linux-MM/