From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarek Poplawski Subject: Re: [PATCH net-next-2.6] net: pskb_expand_head() optimization Date: Mon, 20 Sep 2010 12:12:32 +0000 Message-ID: <20100920121232.GA9931@ff.dom.local> References: <1283852248.2338.160.camel@edumazet-laptop> <20100910.125449.235704956.davem@davemloft.net> <20100911123140.GA1939@del.dom.local> <20100919.171725.245378386.davem@davemloft.net> <20100920072149.GA6353@ff.dom.local> <1284973320.3420.49.camel@edumazet-laptop> <20100920091425.GA8381@ff.dom.local> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: David Miller , netdev@vger.kernel.org To: Eric Dumazet Return-path: Received: from mail-bw0-f46.google.com ([209.85.214.46]:61866 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755965Ab0ITMMf (ORCPT ); Mon, 20 Sep 2010 08:12:35 -0400 Received: by bwz11 with SMTP id 11so4163416bwz.19 for ; Mon, 20 Sep 2010 05:12:33 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20100920091425.GA8381@ff.dom.local> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Sep 20, 2010 at 09:14:25AM +0000, Jarek Poplawski wrote: > On Mon, Sep 20, 2010 at 11:02:00AM +0200, Eric Dumazet wrote: > > Le lundi 20 septembre 2010 ?? 07:21 +0000, Jarek Poplawski a =E9cri= t : > > > Btw, I wonder what is the exact reason we can't use only > > > NET_SKBUFF_DATA_USES_OFFSET? > >=20 > > I see no real reason. > >=20 > > On 32bit arches, it might be faster to manipulate pointers, and not > > 'base+offset' values. >=20 > The only reason is code readability and maintenance. Did anybody chec= k > how much faster? Hmm... I probably misread your reasoning. So, if no real reason, really, how about turning this NET_SKBUFF_DATA_USES_OFFSET on unconditionally in net-next, until somebody spots the difference? Jarek P.