netdev - Re: [PATCH net-next-2.6] inetpeer: lower false sharing effect

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Message-Id: <20110608.233145.255635792817750847.davem@davemloft.net>
Date:	Wed, 08 Jun 2011 23:31:45 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	netdev@...r.kernel.org, andi@...stfloor.org,
	tim.c.chen@...ux.intel.com
Subject: Re: [PATCH net-next-2.6] inetpeer: lower false sharing effect

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Thu, 09 Jun 2011 08:26:50 +0200

> Profiles show false sharing in addr_compare() because refcnt/dtime
> changes dirty the first inet_peer cache line, where are lying the keys
> used at lookup time. If many cpus are calling inet_getpeer() and
> inet_putpeer(), or need frag ids, addr_compare() is in 2nd position in
> "perf top".
> 
> Before patch, my udpflood bench (16 threads) on my 2x4x2 machine :
 ..
> After patch, no more addr_compare() in profiles :
 ..
> Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
> CC: Andi Kleen <andi@...stfloor.org>
> CC: Tim Chen <tim.c.chen@...ux.intel.com>

Applied, thanks!
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