From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3911E8CB.AD90A518@sgi.com> Date: Thu, 04 May 2000 14:16:59 -0700 From: Rajagopal Ananthanarayanan MIME-Version: 1.0 Subject: Re: Oops in __free_pages_ok (pre7-1) (Long) (backtrace) References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: riel@nl.linux.org, Kanoj Sarcar , linux-mm@kvack.org, "David S. Miller" List-ID: Linus Torvalds wrote: > > On Thu, 4 May 2000, Rik van Riel wrote: > > > On Thu, 4 May 2000, Linus Torvalds wrote: > > > > > Note that changing how hard try_to_free_pages() tries to free a page is > > > exactly part of what Rik has been doing, so this is something that has > > > changed recently. It's not trivial to get right, for a very simple reason: > > > we need to balance the "hardness" between the VM area scanning and the RLU > > > list scanning. > > > > With the current scheme, it's pretty much impossible to get it > > right. > > Not really. That is what the "priority levels" are really there for: for [ ... discussion about shrink_mmap() ... ] > This, I think, is where the new swap_out() falls down flat on its face. It [ ... discussion about swap_out() ... ] I looked over the latest (7-4) implementation of swap_out, shrink_mmap & try_to_free_pages, etc. One clarification: In the case I reported only dbench was running, presumably doing a lot of read/write. So, why isn't shrink_mmap able to find freeable pages? Is it because the shrink_mmap() is too conservative about implementing LRU? I mean, it doesn't make sense to swap pages just to keep others in cache ... if the demand is too high, start shooting down pages regardless. Or, is shrink_mmap bailing not because of referenced bit, but because bdflush is too slow, for example? That is, are the pages having active I/O so can't be freed? Do you guys think a profile using gcc-style mcount would be useful? -- -------------------------------------------------------------------------- Rajagopal Ananthanarayanan ("ananth") Member Technical Staff, SGI. -------------------------------------------------------------------------- -- 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/