Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964865AbVIMQfh (ORCPT ); Tue, 13 Sep 2005 12:35:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964870AbVIMQfg (ORCPT ); Tue, 13 Sep 2005 12:35:36 -0400 Received: from ns1.lanforge.com ([66.165.47.210]:51683 "EHLO www.lanforge.com") by vger.kernel.org with ESMTP id S964867AbVIMQff (ORCPT ); Tue, 13 Sep 2005 12:35:35 -0400 Message-ID: <4326FFC2.7030803@candelatech.com> Date: Tue, 13 Sep 2005 09:35:14 -0700 From: Ben Greear Organization: Candela Technologies User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.7.10) Gecko/20050719 Fedora/1.7.10-1.3.1 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Stephen Hemminger CC: Ravikiran G Thirumalai , Andrew Morton , linux-kernel@vger.kernel.org, dipankar@in.ibm.com, bharata@in.ibm.com, shai@scalex86.org, Rusty Russell , netdev@vger.kernel.org, davem@davemloft.net Subject: Re: [patch 7/11] net: Use bigrefs for net_device.refcount References: <20050913155112.GB3570@localhost.localdomain> <20050913161012.GI3570@localhost.localdomain> <20050913092659.791bddec@localhost.localdomain> In-Reply-To: <20050913092659.791bddec@localhost.localdomain> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1118 Lines: 34 Stephen Hemminger wrote: > On Tue, 13 Sep 2005 09:10:12 -0700 > Ravikiran G Thirumalai 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? We grab and drop a reference for each poll of a device, roughly. See dev_hold in _netif_rx_schedule(struct net_device *dev) in include/netdevice.h, for instance. Thanks, Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/