Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933318AbZDASII (ORCPT ); Wed, 1 Apr 2009 14:08:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933297AbZDASHj (ORCPT ); Wed, 1 Apr 2009 14:07:39 -0400 Received: from gw.goop.org ([64.81.55.164]:37276 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933293AbZDASHi (ORCPT ); Wed, 1 Apr 2009 14:07:38 -0400 Message-ID: <49D3AD61.5090206@goop.org> Date: Wed, 01 Apr 2009 11:07:29 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Eric Dumazet CC: Ingo Molnar , Tejun Heo , linux kernel , Linux Netdev List , Joe Perches , Rusty Russell Subject: Re: [PATCH] x86: percpu_to_op() misses memory and flags clobbers References: <49D32212.80607@cosmosbay.com> <49D32DC2.9010003@goop.org> <49D33E80.70802@cosmosbay.com> <20090401161218.GB3859@elte.hu> <49D3A0C2.9000403@cosmosbay.com> In-Reply-To: <49D3A0C2.9000403@cosmosbay.com> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 627 Lines: 16 Eric Dumazet wrote: > +#define percpu_inc(var) percpu_to_op0("inc", per_cpu__##var) > +#define percpu_dec(var) percpu_to_op0("dec", per_cpu__##var) > There's probably not a lot of value in this. The Intel and AMD optimisation guides tend to deprecate inc/dec in favour of using add/sub, because the former can cause pipeline stalls due to its partial flags update. J -- 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/