From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932300Ab0FGHuG (ORCPT ); Mon, 7 Jun 2010 03:50:06 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:63341 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1756368Ab0FGHuF (ORCPT ); Mon, 7 Jun 2010 03:50:05 -0400 Message-ID: <4C0CA4BE.9000703@cn.fujitsu.com> Date: Mon, 07 Jun 2010 15:50:22 +0800 From: Lai Jiangshan User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Theodore Tso , Theodore Tso CC: rostedt@goodmis.org, linux-kernel@vger.kernel.org, Ingo Molnar , Frederic Weisbecker Subject: Re: [PATCH] tracing: reduce latency and remove percpu trace_seq References: <4C078350.7090106@cn.fujitsu.com> <1275572170.15884.30.camel@gandalf.stny.rr.com> <4C0863BD.6000307@cn.fujitsu.com> <1275620590.15884.70.camel@gandalf.stny.rr.com> In-Reply-To: <1275620590.15884.70.camel@gandalf.stny.rr.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Steven Rostedt wrote: > On Fri, 2010-06-04 at 10:23 +0800, Lai Jiangshan wrote: >> Steven Rostedt wrote: >> >>> The "print" in the trace_seq_printf() is the TP_printk() field of the >>> TRACE_EVENT. I believe that there were some events (ext4?) that did >>> things that required preemption disabled. >>> >> It seems that ext4 has no such events. >> I find jbd2_dev_to_name() in the TP_printk() field of ext4's tracepoints. >> And it seems that jbd2_dev_to_name() requires preemption enabled and sleepable. >> >> Maybe there were some events did things that required preemption disabled. >> But No document ensure TP_printk() preemption disabled, such events should >> be fixed, I think. > > Well, I had a private email conversation with Ted last year where IIRC, > adding the preempt disable would fix things. > > I'd like to make sure Ted is OK with removing that before we do so. > > Ted? > Hi, Ted Could you give some comments? I'm waiting and will appreciate your help. Thanx, Lai