From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753934AbZCIJNx (ORCPT ); Mon, 9 Mar 2009 05:13:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752643AbZCIJNO (ORCPT ); Mon, 9 Mar 2009 05:13:14 -0400 Received: from hera.kernel.org ([140.211.167.34]:40800 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752563AbZCIJNM (ORCPT ); Mon, 9 Mar 2009 05:13:12 -0400 Date: Mon, 9 Mar 2009 09:12:34 GMT From: Ingo Molnar To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, peterz@infradead.org, fweisbec@gmail.com, rostedt@goodmis.org, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, fweisbec@gmail.com, rostedt@goodmis.org, peterz@infradead.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <1236356510-8381-5-git-send-email-fweisbec@gmail.com> References: <1236356510-8381-5-git-send-email-fweisbec@gmail.com> Subject: [tip:tracing/printk] tracing: optimize trace_printk() Message-ID: Git-Commit-ID: 7bffc23e56e92c14b787bf4d95249a32085bfed5 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Mon, 09 Mar 2009 09:12:36 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 7bffc23e56e92c14b787bf4d95249a32085bfed5 Gitweb: http://git.kernel.org/tip/7bffc23e56e92c14b787bf4d95249a32085bfed5 Author: "Ingo Molnar" AuthorDate: Mon, 9 Mar 2009 10:11:36 +0100 Commit: Ingo Molnar CommitDate: Mon, 9 Mar 2009 10:11:36 +0100 tracing: optimize trace_printk() Impact: micro-optimization trace_printk() does this unconditionally: trace_printk_fmt = fmt; Where trace_printk_fmt is an entry into a global array. This is very SMP-unfriendly. So only write it once per bootup. Cc: Frederic Weisbecker Cc: Steven Rostedt Cc: Peter Zijlstra LKML-Reference: <1236356510-8381-5-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- include/linux/kernel.h | 10 ++++++++-- 1 files changed, 8 insertions(+), 2 deletions(-) diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 4e726b9..7742798 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -454,7 +454,10 @@ do { \ do { \ static const char *trace_printk_fmt \ __attribute__((section("__trace_printk_fmt"))); \ - trace_printk_fmt = fmt; \ + \ + if (!trace_printk_fmt) \ + trace_printk_fmt = fmt; \ + \ __trace_printk_check_format(fmt, ##args); \ __trace_printk(_THIS_IP_, trace_printk_fmt, ##args); \ } while (0) @@ -467,7 +470,10 @@ __trace_printk(unsigned long ip, const char *fmt, ...) do { \ static const char *trace_printk_fmt \ __attribute__((section("__trace_printk_fmt"))); \ - trace_printk_fmt = fmt; \ + \ + if (!trace_printk_fmt) \ + trace_printk_fmt = fmt; \ + \ __ftrace_vprintk(_THIS_IP_, trace_printk_fmt, vargs); \ } while (0)