Messages in this thread | | | Date | Mon, 8 Dec 2008 15:07:24 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] percpu_counter: Fix __percpu_counter_sum() |
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On Mon, 8 Dec 2008 18:00:47 -0500 Theodore Tso <tytso@mit.edu> 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?
They are allocated with alloc_percpu(), so each CPU's counter lives in a per-cpu area. If you chase through seventeen layers of Rustyness you end up at mm/allocpercpu.c:percpu_populate() which is where that little s32 ends up getting allocated.
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