Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756776AbZDRHpc (ORCPT ); Sat, 18 Apr 2009 03:45:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751994AbZDRHpU (ORCPT ); Sat, 18 Apr 2009 03:45:20 -0400 Received: from mx2.redhat.com ([66.187.237.31]:58991 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751646AbZDRHpU (ORCPT ); Sat, 18 Apr 2009 03:45:20 -0400 Date: Sat, 18 Apr 2009 09:44:28 +0200 From: Jiri Pirko To: Eric Dumazet Cc: Stephen Hemminger , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, jgarzik@pobox.com, davem@davemloft.net, bridge@lists.linux-foundation.org, fubar@us.ibm.com, bonding-devel@lists.sourceforge.net, kaber@trash.net, mschmidt@redhat.com, ivecera@redhat.com Subject: Re: [PATCH 1/3] net: introduce a list of device addresses dev_addr_list (v3) Message-ID: <20090418074427.GB3370@psychotron.englab.brq.redhat.com> References: <20090313183303.GF3436@psychotron.englab.brq.redhat.com> <20090415081720.GA21342@psychotron.englab.brq.redhat.com> <20090415081819.GB21342@psychotron.englab.brq.redhat.com> <20090415180215.GA22540@psychotron.englab.brq.redhat.com> <20090417115723.GE9556@psychotron.englab.brq.redhat.com> <20090417083315.2f089755@nehalam> <20090418070151.GA3370@psychotron.englab.brq.redhat.com> <49E982C4.8020407@cosmosbay.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <49E982C4.8020407@cosmosbay.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1745 Lines: 48 Sat, Apr 18, 2009 at 09:35:32AM CEST, dada1@cosmosbay.com wrote: >Jiri Pirko a ?crit : >> Fri, Apr 17, 2009 at 05:33:15PM CEST, shemminger@vyatta.com wrote: >> >> >> >>>> +struct netdev_hw_addr { >>>> + struct list_head list; >>>> + unsigned char addr[MAX_ADDR_LEN]; >>>> + int refcount; >>>> + struct rcu_head rcu_head; >>>> +}; >>> Minor nit, the ordering of elements cause holes that might not be >>> needed. >> >> Agree that ordering might be done better. Will do. >>> Space saving? is rcu_head needed or would using synchronize_net >>> make code cleaner and save space. >>> >> >> Well I originaly had this done by synchronize_rcu(). Eric argued that it might >> cause especially __hw_addr_del_multiple_ii() to run long and suggested to use >> call_rcu() instead. I plan to switch this to kfree_rcu() (or whatever it's >> called) once it hits the tree. >> > >Yes, and dont forget we wont save space, as we allocate a full >cache line to hold a 'struct netdev_hw_addr', since we dont want this >critical and read_mostly object polluted by a hot spot elsewhere in kernel... > >Considering this, letting 'rcu_head' at the end of structure, even if we >have an eventual hole on 64 bit arches is not really a problem, and IMHO >the best thing to do, as rcu_head is only used at dismantle time. I will order the struct better, there are archs with small cache line size where it makes sense. > >And yes, maybe kfree_rcu() will makes its way in kernel, eventually :) > >Thank you > > -- 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/