From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756820AbZETJTT (ORCPT ); Wed, 20 May 2009 05:19:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756718AbZETJTH (ORCPT ); Wed, 20 May 2009 05:19:07 -0400 Received: from mx1.redhat.com ([66.187.233.31]:49835 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755876AbZETJTG (ORCPT ); Wed, 20 May 2009 05:19:06 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: Roland McGrath To: Peter Zijlstra X-Fcc: ~/Mail/linus Cc: Jason Baron , linux-kernel@vger.kernel.org, fweisbec@gmail.com, mingo@elte.hu, laijs@cn.fujitsu.com, rostedt@goodmis.org, mathieu.desnoyers@polymtl.ca, jiayingz@google.com, mbligh@google.com, fche@redhat.com Subject: Re: [PATCH 0/3] tracepoints: delay argument evaluation In-Reply-To: Peter Zijlstra's message of Wednesday, 20 May 2009 09:38:47 +0200 <1242805127.26820.532.camel@twins> References: <1242803524.26820.530.camel@twins> <20090520072750.DA9A0FC38D@magilla.sf.frob.com> <1242805127.26820.532.camel@twins> Emacs: Our Lady of Perpetual Garbage Collection Message-Id: <20090520091817.8E3EEFC38D@magilla.sf.frob.com> Date: Wed, 20 May 2009 02:18:17 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > But I think we should be asking GCC to get fixed. Since inline functions > don't act like a compiler barrier anyway, they might as well not force > argument evaluation either. I quite agree. I'm all for better compilation. However, usual practice in the kernel has been to complain about introducing C code sequences that add a few instructions when compiled by compilers over 5 years old, let alone the very latest one. I think it was the expectation of that sort of sensitive reaction to the hot-path impact of unused tracepoints that motivated Jason's attempt at microoptimization. Thanks, Roland