From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <394BEEFF.C194F59E@norran.net> Date: Sat, 17 Jun 2000 23:34:55 +0200 From: Roger Larsson MIME-Version: 1.0 Subject: Re: kswapd eating too much CPU on ac16/ac18 References: <20000617164317.A9421@cesarb.personal> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Cesar Eduardo Barros Cc: linux-mm@kvack.org, linux-kernel@vger.rutgers.edu List-ID: Hi, The reason for me to ask you to remove it is since there are two problems related to this code snippet. (Reported earlier on linux-mm) * If no zone has pressure - we will loop "forever" since no pages will pass this test. (On a 16 MB machine this is the likely scenario) * If there are no pages of a zone with pressure are on LRU - we will loop... And since there is no guarantee that shrink_mmap is not called in these circumstances... I have released patches (on linux-mm) that tries to handle these situations. * do_try_to_free_pages avoids to call shrink_mmap with no pressure. * shrink_mmap tries to determine the bad situation (not in my latest) /RogerL Cesar Eduardo Barros wrote: > > > Please try to remove only this test to get a comparable result. > > I nuked the whole block: > > /* > * Page is from a zone we don't care about. > * Don't drop page cache entries in vain. > */ > if (page->zone->free_pages > page->zone->pages_high) { > /* the page from the wrong zone doesn't count */ > count++; > goto unlock_continue; > } > > Commenting it out made ac19 perform almost as good as ac4 (it looked a bit > faster). > > I don't know how it would affect boxes with more than one zone, but my gut > feeling is that it won't hurt and might make them even a bit faster. > > -- > Cesar Eduardo Barros > cesarb@nitnet.com.br > cesarb@dcc.ufrj.br > -- > 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/ -- Home page: http://www.norran.net/nra02596/ -- 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/