From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 19 Jun 2000 18:07:34 -0300 (BRST) From: Rik van Riel Subject: Re: shrink_mmap() change in ac-21 In-Reply-To: <87r99t8m2r.fsf@atlas.iskon.hr> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Zlatko Calusic Cc: alan@redhat.com, linux-mm@kvack.org, linux-kernel@vger.rutgers.edu, "Juan J. Quintela" List-ID: On 19 Jun 2000, Zlatko Calusic wrote: > The shrink_mmap() change in your latest prepatch (ac12) doesn't look > very healthy. Removing the test for the wrong zone we effectively > discard lots of wrong pages before we get to the right one. That is > effectively flushing the page cache and we have unbalanced system. > > For example, check the "vmstat 1" output below, done while I was > reading a big file from the disk. At some point in time, the page > cache shrunk to almost half of its size (75MB -> 42MB). > > The reason is balancing of the DMA zone (which is much smaller on a > 128MB machine than the NORMAL zone!). shrink_mmap() now happily evicts > wrong pages from the memory and continues doing so until it finally > frees enough pages from the DMA zone. That, of course, hurts caching > as the page cache gets shrunk a lot without a good reason. I already suspected this could happen. /me looks at quintela Juan, didn't you and Roger have a patch to solve this? ;) (I think quintela and roger already have a patch so I'll save writing one myself) regards, Rik -- The Internet is not a network of computers. It is a network of people. That is its real strength. Wanna talk about the kernel? irc.openprojects.net / #kernelnewbies http://www.conectiva.com/ http://www.surriel.com/ -- 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/