Messages in this thread | | | Date | Thu, 25 Jan 2007 13:19:52 +0530 | From | Vaidyanathan Srinivasan <> | Subject | Re: [RFC] Limit the size of the pagecache |
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Aubrey Li wrote: > On 1/25/07, Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> wrote: >> >> Christoph Lameter wrote: >>> On Wed, 24 Jan 2007, Vaidyanathan Srinivasan wrote: >>> >>>> With your patch, MMAP of a file that will cross the pagecache limit hangs the >>>> system. As I mentioned in my previous mail, without subtracting the >>>> NR_FILE_MAPPED, the reclaim will infinitely try and fail. >>> Well mapped pages are still pagecache pages. >>> >> Yes, but they can be classified under a process RSS pages. Whether it >> is an anon page or shared mem or mmap of pagecache, it would show up >> under RSS. Those pages can be limited by RSS limiter similar to the >> one we are discussing in pagecache limiter. In my opinion, once a >> file page is mapped by the process, then it should be treated at par >> with anon pages. Application programs generally do not mmap a file >> page if the reuse for the content is very low. >> > > I agree, we shouldn't take mmapped page into account. > But Vaidy - even with your patch, we are still using the existing > reclaimer, that means we dont ensure that only page cache is > reclaimed/limited. mapped pages will be hit also. > I think we still need to add a new scancontrol field to lock mmaped > pages and remove unmapped pagecache pages only.
I have tried to add scan control to Roy's patch at http://lkml.org/lkml/2007/01/17/96
In that patch, we search and remove only pages that are not mapped. We also remove referenced and hot pagecache pages which the normal reclaimer is not expected to consider.
I will try to fit that logic in Christoph's patch and test.
--Vaidy
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