Messages in this thread | | | Date | Mon, 5 Feb 2007 10:38:47 -0600 | From | Matt Mackall <> | Subject | Re: [RFC] Tracking mlocked pages and moving them off the LRU |
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On Mon, Feb 05, 2007 at 09:39:34AM +0100, Arjan van de Ven wrote: > On Sun, 2007-02-04 at 23:57 -0800, Christoph Lameter wrote: > > Hmmm.. I have had no time to test this one yet but I think this should > > work. It uses the delayed method and a new page flag PageMlocked() with > > different semantics. Fix for page migration is also included. > > > > Patch avoids to put new anonymous mlocked pages on the LRU. Maybe the same > > could be done for new pagecache pages? > > > > I still need a solution for the problem of not having enough page flag > > bits on i386 NUMA. > > I still don't get why you *really* need such a bit.
There are three possibilities mentioned so far:
1) slow accounting - scan each attached VMA on each mmap/munmap 2) lazy accounting - the same as above, with the work all moved to the LRU sweep 3) accounting with an extra page flag - still needs to scan VMAs on munmap
Christoph seems to prefer the third.
I wonder if we couldn't stick a rough counter in address_space to fast-path the slow accounting - we'll typically only have 0 or 1 locks active.
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