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    SubjectRe: [15/17] SLUB: Support virtual fallback via SLAB_VFALLBACK
    On Fri, 28 Sep 2007 20:25:50 +0200 Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:

    >
    > On Fri, 2007-09-28 at 11:20 -0700, Christoph Lameter wrote:
    >
    > > > start 2 processes that each mmap a separate 64M file, and which does
    > > > sequential writes on them. start a 3th process that does the same with
    > > > 64M anonymous.
    > > >
    > > > wait for a while, and you'll see order=1 failures.
    > >
    > > Really? That means we can no longer even allocate stacks for forking.
    > >
    > > Its surprising that neither lumpy reclaim nor the mobility patches can
    > > deal with it? Lumpy reclaim should be able to free neighboring pages to
    > > avoid the order 1 failure unless there are lots of pinned pages.
    > >
    > > I guess then that lots of pages are pinned through I/O?
    >
    > memory got massively fragemented, as anti-frag gets easily defeated.
    > setting min_free_kbytes to 12M does seem to solve it - it forces 2 max
    > order blocks to stay available, so we don't mix types. however 12M on
    > 128M is rather a lot.
    >
    > its still on my todo list to look at it further..
    >

    That would be really really bad (as in: patch-dropping time) if those
    order-1 allocations are not atomic.

    What's the callsite?
    -
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