Messages in this thread | | | Date | Fri, 05 Sep 2008 10:52:10 +0900 | From | KOSAKI Motohiro <> | Subject | Re: [PATCH 4/4] capture pages freed during direct reclaim for allocation by the reclaimer |
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> > Hi Andy, > > > > I like almost part of your patch. > > (at least, I can ack patch 1/4 - 3/4) > > > > So, I worry about OOM risk. > > Can you remember desired page size to capture list (or any other location)? > > if possible, __capture_on_page can avoid to capture unnecessary pages. > > > > So, if __capture_on_page() can make desired size page by buddy merging, > > it can free other pages on capture_list. > > > > In worst case, shrink_zone() is called by very much process at the same time. > > Then, if each process doesn't back few pages, very many pages doesn't be backed. > > The testing we have done pushes the system pretty damn hard, about as > hard as you can. Without the zone watermark checks in capture we would > periodically lose a test to an OOM. Since adding that I have never seen > an OOM, so I am confident we are safe. That said, clearly some wider > testing in -mm would be very desirable to confirm that this does not > tickle OOM for some unexpected workload. > > I think the idea of trying to short-circuit capture once it has a page > of the requisit order or greater is eminently sensible. I suspect we > are going to have trouble getting the information to the right place, > but it is clearly worth investigating. It feels like a logical step on > top of this, so I would propose to do it as a patch on top of this set. > > Thanks for your feedback.
Ok. makes sense. Thanks for good patch.
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
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