From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <39178682.9AA1AB59@sgi.com> Date: Mon, 08 May 2000 20:31:14 -0700 From: Rajagopal Ananthanarayanan 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: "Quintela Carreira Juan J." , Andrea Arcangeli , Benjamin Redelings I , linux-mm@kvack.org List-ID: Linus Torvalds wrote: > [ ... ] > > The "don't page out pages from zones that don't need it" test is a good > test, but it turns out that it triggers a rather serious problem: the way > the buffer cache dirty page handling is done is by having shrink_mmap() do > a "try_to_free_buffers()" on the pages it encounters that have > "page->buffer" set. > > And doing that is quite important, because without that logic the buffers > don't get written to disk in a timely manner, nor do already-written > buffers get refiled to their proper lists. So you end up being "out of > memory" - not because the machine is really out of memory, but because > those buffers have a tendency to stick around if they aren't constantly > looked after by "try_to_free_buffers()". > > So the real fix ended up being to re-order the tests in shrink_mmap() a > bit, so that try_to_free_buffers() is called even for pages that are on > a good zone that doesn't need any real balancing.. Not sure entirely what effect this has, except for freeing underlying buffer_head's. The page itself is still skipped. Anyway, brief examination shows that you've changed several things here (in 7-7), so I'll have to go at it some more time to get a full picture. > > [ time passes ] > > pre7-7 is there now. > > Linus Unfortunately my dbench test really runs bad with pre 7-7. Quantitively, the amount of memory in "cache" of vmstat is higher than before. write()'s start failing. More later, -- -------------------------------------------------------------------------- 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/