From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3913AF3E.470F26E@ucla.edu> Date: Fri, 05 May 2000 22:35:58 -0700 From: Benjamin Redelings I MIME-Version: 1.0 Subject: Re: [DATAPOINT] pre7-6 will not swap References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: Rajagopal Ananthanarayanan , linux-mm@kvack.org List-ID: > and I suspect that we mightactually make the vmscan.c test more eager to > swap stuff out: my private source tree says > > /* > * Don't do any of the expensive stuff if > * we're not really interested in this zone. > */ > if (z->free_pages > z->pages_high) > goto out_unlock; > > in vmscan.c, and that seems to be quite well-behaved too (but if somebody > has the energy to test the two different versions, I'd absolutely love to > hear results..) Although I would have thought that putting this test in would have no effect on performance, it actually kills performance. Since the test appears very reasonable, I think this means we have a bug elsewhere, and that removing this reasonable test cures a symptom, but not the bug. OK, details. With Linus's test, the kernel does not want to swap much. It is a little better than the pervious version of the test, but much lower than if the test was removed. One result is that the cache shrinks to low sizes like 14Mb/64Mb, when there are several unused daemons that could be swapped out. Also, the WRONG PROCESSES are swapped out. Several large daemons that were swapped out w/o the test, are now left in core. Instead, RUNNING programs are swapped out, like netscape. Even worse, running xquake and 'tar -xf linux.tar' makes the system non-responsive - the VM continues paging the quake ENGINE in and out and in and out :P It looks like some processes (my unused daemons) are scanned only once, and then get stuck at the end of some list? Is that a possible explanation? Perhaps Rik's moving list-head idea is needed? . carry on, -benRI -- "I want to be in the light, as He is in the Light, I want to shine like the stars in the heavens." - DC Talk, "In the Light" Benjamin Redelings I <>< http://www.bol.ucla.edu/~bredelin/ -- 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/