Messages in this thread | | | Date | Mon, 20 Mar 2017 15:59:38 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to refcount_t |
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On Mon, Mar 20, 2017 at 07:51:01AM -0700, Eric Dumazet wrote: > PowerPC has no efficient atomic_inc() and this definitely shows on > network intensive workloads involving concurrent cores/threads.
Correct, PPC LL/SC are dreadfully expensive.
> atomic_cmpxchg() on PowerPC is horribly more expensive because of the > added two SYNC instructions.
Note that refcount_t uses atomic_cmpxchg_release() and atomic_cmpxchg_relaxed() which avoid most of the painful barriers.
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