From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754982AbXLCLzM (ORCPT ); Mon, 3 Dec 2007 06:55:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753651AbXLCLy5 (ORCPT ); Mon, 3 Dec 2007 06:54:57 -0500 Received: from rhun.apana.org.au ([64.62.148.172]:4986 "EHLO arnor.apana.org.au" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753633AbXLCLy4 (ORCPT ); Mon, 3 Dec 2007 06:54:56 -0500 Date: Mon, 3 Dec 2007 22:54:35 +1100 From: Herbert Xu To: Alexey Kuznetsov Cc: Wang Chen , Gerrit Renker , davem@davemloft.net, andi@firstfloor.org, netdev@vger.kernel.org, Linux Kernel Mailing List , Christoph Lameter , Ingo Molnar Subject: Re: [PATCH 3/3] [UDP6]: Counter increment on BH mode Message-ID: <20071203115435.GA4202@gondor.apana.org.au> References: <474F7EE8.2040009@cn.fujitsu.com> <474F8255.5060501@cn.fujitsu.com> <20071130111949.GB28277@gerrit.erg.abdn.ac.uk> <20071201015438.GC26895@gondor.apana.org.au> <4753AE07.1040906@cn.fujitsu.com> <20071203113935.GA25124@gondor.apana.org.au> <20071203114912.GA4425@ms2.inr.ac.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071203114912.GA4425@ms2.inr.ac.ru> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 03, 2007 at 02:49:12PM +0300, Alexey Kuznetsov wrote: > On Mon, Dec 03, 2007 at 10:39:35PM +1100, Herbert Xu wrote: > > So we need to fix this, and whatever the fix is will probably render > > the BH/USER distinction obsolete. > > Hmm, I would think opposite. USER (or generic) is expensive variant, > BH is lite. No? Yes that would certainly be the obvious fix. In other words, just use smp_processor_id instead of the raw version. I suppose the only issue would be that disabling/enabling preemption isn't exactly cost-free and we're going to be doing that for every single increment. Hmm, wasn't someone else talking about a non-atomic version of atomic ops lately (i.e., atomic with respect to the local CPU only)? Perhaps this is the killer app for it :) Thanks, -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt