Re: [PATCH] percpu_counter: Fix __percpu_counter_sum()

Theodore Tso
2008-12-08T23:01:19Z

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?

- Ted