Messages in this thread | | | Date | Tue, 18 Oct 2011 17:56:23 -0700 (PDT) | From | Hugh Dickins <> | Subject | Re: [PATCH] mm: munlock use mapcount to avoid terrible overhead |
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On Tue, 18 Oct 2011, Andrew Morton wrote: > On Tue, 18 Oct 2011 17:02:56 -0700 (PDT) > Hugh Dickins <hughd@google.com> wrote: > > > A process spent 30 minutes exiting, just munlocking the pages of a large > > anonymous area that had been alternately mprotected into page-sized vmas: > > for every single page there's an anon_vma walk through all the other > > little vmas to find the right one. > > And how long did the test case take with the patch applied?
5 seconds in the case tried; but the issue is quadratic, so you can make the improvement look arbitrarily good.
Hugh
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