From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758726AbZB0RDg (ORCPT ); Fri, 27 Feb 2009 12:03:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756525AbZB0RD1 (ORCPT ); Fri, 27 Feb 2009 12:03:27 -0500 Received: from mx2.redhat.com ([66.187.237.31]:53212 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756417AbZB0RD0 (ORCPT ); Fri, 27 Feb 2009 12:03:26 -0500 Message-ID: <49A81D05.4040807@redhat.com> Date: Fri, 27 Feb 2009 12:04:05 -0500 From: Masami Hiramatsu User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: Steven Rostedt CC: Ingo Molnar , Peter Zijlstra , Frederic Weisbecker , LKML , Arnaldo Carvalho de Melo , systemtap-ml Subject: Re: [PATCH] tracing/ftrace: add missing wake-up on some callsites References: <49a1cc8f.2283420a.54d2.ffff8461@mx.google.com> <20090223162630.GG5961@nowhere> <20090223170528.GH5961@nowhere> <20090223173714.GA601@elte.hu> In-Reply-To: X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=ISO-8859-1 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 Mon, 23 Feb 2009, Ingo Molnar wrote: > >> * Steven Rostedt wrote: >> >>>> Which would send a delayed work to wake up? >>> No, I was thinking that trace_delay_wake_up() would be called >>> by these dangerous call sites. Then a per_cpu flag could be >>> set. We could have a trace point in the scheduler code that is >>> outside holding a runqueue lock, and this trace point would >>> call a trace function that will clear the per cpu flag, and >>> then call trace_wake_up(). >> No, that's very roundabout and ugly. If we putting a tracepoint >> there we might as well put real scheduler code there that looks >> for such a flag. But i'm not convinced we need a flag ... > > Just a suggestion. I was trying to keep the tracer from being an overhead. > But what else would you suggest? Just having the scheduler call > trace_wakeup? Actually, Systemtap(LTTng too?) also has same problem. Currently, we're using a periodical timer to wake the reader process up. I assume if we can put a tracepoint at the beginning of schedule(), we can share it. Thank you, > > -- Steve > > -- > 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/ -- Masami Hiramatsu Software Engineer Hitachi Computer Products (America) Inc. Software Solutions Division e-mail: mhiramat@redhat.com