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Message-ID: <1490196147.16816.162.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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        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        James Morris <jmorris@namei.org>, Patrick McHardy <kaber@trash.net>,
        Stephen Hemminger <stephen@networkplumber.org>,
        Hans Liljestrand <ishkamiel@gmail.com>,
        David Windsor <dwindsor@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>
Date: Wed, 22 Mar 2017 08:22:27 -0700
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On Wed, 2017-03-22 at 16:08 +0100, Peter Zijlstra wrote:
> On Wed, Mar 22, 2017 at 07:54:04AM -0700, Eric Dumazet wrote:
> > 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.
> 
> Is there really no micro bench that exercises the relevant network
> paths? Do you really fully rely on Google production workloads?

You could run a synflood test, with ~10 Mpps.

sock_hold() is definitely used in SYN handling.

Last upstream kernels do not work on my lab hosts, for whatever reason.