From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <shemminger@osdl.org>
Subject: Re: [patch 7/11] net: Use bigrefs for net_device.refcount
Date: Tue, 13 Sep 2005 09:26:59 -0700
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Cc: Andrew Morton <akpm@osdl.org>, linux-kernel@vger.kernel.org,
	dipankar@in.ibm.com, bharata@in.ibm.com, shai@scalex86.org,
	Rusty Russell <rusty@rustcorp.com.au>, netdev@vger.kernel.org,
	davem@davemloft.net
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To: Ravikiran G Thirumalai <kiran@scalex86.org>
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On Tue, 13 Sep 2005 09:10:12 -0700
Ravikiran G Thirumalai <kiran@scalex86.org> wrote:

> The net_device has a refcnt used to keep track of it's uses.
> This is used at the time of unregistering the network device
> (module unloading ..) (see netdev_wait_allrefs) .
> For loopback_dev , this refcnt increment/decrement  is causing
> unnecessary traffic on the interlink for NUMA system
> affecting it's performance.  This patch improves tbench numbers by 6% on a
> 8way x86 Xeon (x445).
> 

Since when is bringing a network device up/down performance critical?