Messages in this thread | | | Date | Thu, 15 Oct 2009 23:23:24 +0100 (BST) | From | Hugh Dickins <> | Subject | Re: [PATCH 8/9] swap_info: note SWAP_MAP_SHMEM |
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On Thu, 15 Oct 2009, KAMEZAWA Hiroyuki wrote: > On Thu, 15 Oct 2009 01:57:28 +0100 (BST) > Hugh Dickins <hugh.dickins@tiscali.co.uk> wrote: > > > While we're fiddling with the swap_map values, let's assign a particular > > value to shmem/tmpfs swap pages: their swap counts are never incremented, > > and it helps swapoff's try_to_unuse() a little if it can immediately > > distinguish those pages from process pages. > > > > Since we've no use for SWAP_MAP_BAD | COUNT_CONTINUED, > > we might as well use that 0xbf value for SWAP_MAP_SHMEM. > > > > Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> > > I welcome this!
Ah, I did wonder whether you might find some memcg use for it too: I'm guessing your welcome means that you do have some such in mind.
(By the way, there's no particular need to use that 0xbf value: during most of my testing I was using SWAP_MAP_SHMEM 0x3e and SWAP_MAP_MAX 0x3d; but then noticed that 0xbf just happened to be free, and also happened to sail through the tests in the right way. But if it ever becomes a nuisance there, no problem to move it.)
Hugh
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