From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262221AbTIWSGa (ORCPT ); Tue, 23 Sep 2003 14:06:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262223AbTIWSGa (ORCPT ); Tue, 23 Sep 2003 14:06:30 -0400 Received: from verein.lst.de ([212.34.189.10]:56758 "EHLO mail.lst.de") by vger.kernel.org with ESMTP id S262221AbTIWSG2 (ORCPT ); Tue, 23 Sep 2003 14:06:28 -0400 Date: Tue, 23 Sep 2003 20:06:21 +0200 From: Christoph Hellwig To: "David S. Miller" Cc: akpm@osdl.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] softirq_pending() Message-ID: <20030923180621.GA18794@lst.de> Mail-Followup-To: Christoph Hellwig , "David S. Miller" , akpm@osdl.org, linux-kernel@vger.kernel.org References: <20030923144847.GA16139@lst.de> <20030923105841.27809d11.davem@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030923105841.27809d11.davem@redhat.com> User-Agent: Mutt/1.3.28i X-Spam-Score: -5 () EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 23, 2003 at 10:58:41AM -0700, David S. Miller wrote: > The problem is that, on some of the platforms that don't ignore > the argument, the code generation is much better. > > GCC doesn't consider smp_processor_id() like some const local > variable, so multiple invocations are assumed to return different > values because in many cases 'current_thread_info()' is obscured. > > Your patch is going to make a lot of new code get generated on > x86 for example, so I don't think it should be applied even though > my own platforms are not effected by this issue. Okay, thanks forthe explanation. I don't think it matters in this case because there's exactly one case where we pass an variable into softirq_pending() instead of a direct, uncached smp_processor_id() - and that is in arch/cris/ which is UP only. I'll try to remember the hint so I know what do to this pops up the next time, though :)