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    SubjectRe: [PATCH] percpu_counter: Fix __percpu_counter_sum()
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    On Tue, 2008-12-09 at 00:05 +0100, Peter Zijlstra wrote:
    > On Mon, 2008-12-08 at 18:00 -0500, Theodore Tso wrote:
    > > On Mon, Dec 08, 2008 at 11:20:35PM +0100, Peter Zijlstra wrote:
    > > >
    > > > atomic_t is pretty good on all archs, but you get to keep the cacheline
    > > > ping-pong.
    > > >
    > >
    > > Stupid question --- if you're worried about cacheline ping-pongs, why
    > > aren't each cpu's delta counter cacheline aligned? With a 64-byte
    > > cache-line, and a 32-bit counters entry, with less than 16 CPU's we're
    > > going to be getting cache ping-pong effects with percpu_counter's,
    > > right? Or am I missing something?
    >
    > sorta - a new per-cpu allocator is in the works, but we do cacheline
    > align the per-cpu allocations (or used to), also, the allocations are
    > node affine.

    Indeed we still (or again) do, see mm/allocpercpu.c:percpu_populate().



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