Message-ID: <1490021946.16816.54.camel@edumazet-glaptop3.roam.corp.google.com>
Subject: Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to
 refcount_t
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
        David Miller <davem@davemloft.net>, elena.reshetova@intel.com,
        keescook@chromium.org, netdev@vger.kernel.org,
        bridge@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
        kuznet@ms2.inr.ac.ru, jmorris@namei.org, kaber@trash.net,
        stephen@networkplumber.org, ishkamiel@gmail.com, dwindsor@gmail.com,
        akpm@linux-foundation.org
Date: Mon, 20 Mar 2017 07:59:06 -0700
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On Mon, 2017-03-20 at 07:51 -0700, Eric Dumazet wrote:

> atomic_cmpxchg() on PowerPC is horribly more expensive because of the
> added two SYNC instructions.

Although I just saw that refcount was using atomic_cmpxchg_relaxed()

Time to find some documentation (probably missing) or get some specs for
this thing.