Date: Fri, 18 May 2001 23:18:37 -0300 (BRST) From: Rik van Riel <riel@conectiva.com.br> To: Jonathan Morton <chromi@cyberspace.org> Cc: Matt Dillon <dillon@earth.backplane.com>, Terry Lambert <tlambert2@mindspring.com>, Charles Randall <crandall@matchlogic.com>, Roger Larsson <roger.larsson@norran.net>, arch@FreeBSD.ORG, linux-mm@kvack.org, sfkaplan@cs.amherst.edu Subject: Re: on load control / process swapping Message-ID: <Pine.LNX.4.21.0105182315430.5531-100000@imladris.rielhome.conectiva> In-Reply-To: <l03130302b72ad6e553b5@[192.168.239.105]>
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On Fri, 18 May 2001, Jonathan Morton wrote: > FWIW, I've been running with a 2-line hack in my kernel for some weeks > now, which essentially forces the RSS of each process not to be forced > below some arbitrary "fair share" of the physical memory available. > It's not a very clean hack, but it improves performance by a very > large margin under a thrashing load. The only problem I'm seeing is a > deadlock when I run out of VM completely, but I think that's a > separate issue that others are already working on. I'm pretty sure I know what you're running into. Say you guarantee a minimum of 3% of memory for each process; now when you have 30 processes running your memory is full and you cannot reclaim any pages when one of the processes runs into a page fault. The minimum RSS guarantee is a really nice thing to prevent the proverbial root shell from thrashing, but it really only works if you drop such processes every once in a while and swap them out completely. You especially need to do this when you're getting tight on memory and you have idle processes sitting around using their minimum RSS worth of RAM ;) It'd work great together with load control though. I guess I should post a patch for - simple&naive - load control code once I've got the inodes and the dirty page writeout code balancing fixed. regards, Rik -- Virtual memory is like a game you can't win; However, without VM there's truly nothing to lose... http://www.surriel.com/ http://distro.conectiva.com/ Send all your spam to aardvark@nl.linux.org (spam digging piggy) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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