netdev - Re: [PATCH net-2.6.26 2/5][SOCK]: Introduce a percpu inuse counters array (v2).

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Message-Id: <20080328.164024.209852324.davem@davemloft.net>
Date:	Fri, 28 Mar 2008 16:40:24 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	dada1@...mosbay.com
Cc:	xemul@...nvz.org, netdev@...r.kernel.org
Subject: Re: [PATCH net-2.6.26 2/5][SOCK]: Introduce a percpu inuse
 counters array (v2).

From: Eric Dumazet <dada1@...mosbay.com>
Date: Fri, 28 Mar 2008 18:17:49 +0100

> Pavel Emelyanov a écrit :
> > And redirect sock_prot_inuse_add and _get to use one.
> >
> > As far as the dereferences are concerned. Before the patch we made
> > 1 dereference to proto->inuse.add call, the call itself and then
> > called the __get_cpu_var() on a static variable. After the patch we 
> > make a direct call, then one dereference to proto->inuse_idx and 
> > then the same __get_cpu_var() on a still static variable. So this 
> > patch doesn't seem to produce performance penalty on SMP.
> >
> > This is not per-net yet, but I will deliberately make NET_NS=y case
> > separated from NET_NS=n one, since it'll cost us one-or-two more 
> > dereferences to get the struct net and the inuse counter.
> >
> > Signed-off-by: Pavel Emelyanov <xemul@...nvz.org>
> >
> >   
> 
> Acked-by: Eric Dumazet <dada1@...mosbay.com>

Applied.
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