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Date: Wed, 7 May 2014 06:33:46 +0200
From: Andi Kleen <andi@firstfloor.org>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Andi Kleen <ak@linux.intel.com>,
        Richard Cochran <richardcochran@gmail.com>, josh@joshtriplett.org,
        David Miller <davem@davemloft.net>, andi@firstfloor.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        tom.zanussi@linux.intel.com
Subject: Re: [PATCH 08/24] net, diet: Make TCP metrics optional
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On Tue, May 06, 2014 at 04:29:39PM -0700, Eric Dumazet wrote:
> On Tue, 2014-05-06 at 14:05 -0700, Andi Kleen wrote:
> 
> > - Make GRO optional.
> > This is purely a performance feature for high bandwidth.
> 
> Make this properly then, instead of relying on LTO.
> 
> We did preliminary work to put this stuff in separate files, but its not
> complete yet.

FWIW doesn't matter for LTO.

> 
> tcpv4_offload has pointers to tcp4_gro_receive() and tcp4_gro_complete()
> 
> Is LTO smart enough to understand this will never be called, and do
> proper code elimination of whole _gro_ helpers ?

When there are pointers in static objects it cannot eliminate it for C
(it may work for C++)

However if you just  remove the pointer it'll remove the rest.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.