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Message-ID: <1490194444.16816.154.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: Kees Cook <keescook@chromium.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
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        Stephen Hemminger <stephen@networkplumber.org>,
        Hans Liljestrand <ishkamiel@gmail.com>,
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        Andrew Morton <akpm@linux-foundation.org>
Date: Wed, 22 Mar 2017 07:54:04 -0700
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On Wed, 2017-03-22 at 15:33 +0100, Peter Zijlstra wrote:

> 
> But I would feel a whole lot better about the entire thing if we could
> measure their impact. It would also give us good precedent to whack
> other potential users of _nocheck over the head with -- show numbers.

I wont be able to measure the impact on real workloads, our productions
kernels are based on 4.3 at this moment.

I guess someone could code a lib/test_refcount.c launching X threads
using either atomic_inc or refcount_inc() in a loop.

That would give a rough estimate of the refcount_t overhead among
various platforms.