From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753348AbYLUMVY (ORCPT ); Sun, 21 Dec 2008 07:21:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751797AbYLUMVQ (ORCPT ); Sun, 21 Dec 2008 07:21:16 -0500 Received: from qw-out-2122.google.com ([74.125.92.26]:26122 "EHLO qw-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751480AbYLUMVP (ORCPT ); Sun, 21 Dec 2008 07:21:15 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=sAJ3YdBBBxmyXgYBMGmKkagQKD3iz081/OwHAnhntHkDQvmwrOkbqFehlzYFEEaEsx 4OPwE12rXH81+o4eqgkMtJI6pSz8xnvbSYSfVYZQ+w6pct/EN7K38Op9XrFSSNCOYKzG /lzsLiZQwpNJuBwCU8I6yZh1eZOXftduWkM7M= Message-ID: Date: Sun, 21 Dec 2008 13:21:12 +0100 From: "=?ISO-8859-1?Q?Fr=E9d=E9ric_Weisbecker?=" To: "Ingo Molnar" Subject: Re: [PATCH v2] tracing/function-graph-tracer: prevent from hrtimer interrupt infinite loop Cc: "Thomas Gleixner" , "Steven Rostedt" , "Andrew Morton" , "Linux Kernel" In-Reply-To: <20081221101226.GA6021@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <4949A2CC.6040209@gmail.com> <20081218103459.GD10513@elte.hu> <20081218112216.GE14332@elte.hu> <20081218211637.GF24271@elte.hu> <20081218214458.GA30834@elte.hu> <20081221100047.GA31074@elte.hu> <20081221101226.GA6021@elte.hu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2008/12/21 Ingo Molnar : > > btw., a graph-tracer buglet i noticed: > > 3) | perf_counter_task_tick() { > 3) | perf_counter_task_sched_out() { > 3) | /* c:ffff88049b184000, u:0: 0000000020ca1ab0 + 0000000000000000 = 0000000020ca1ab0 > */ > 3) | /* sched-out counter ffff88049b184000, state: 0 > */ > 3) 5.024 us | } > 3) | perf_counter_task_sched_in() { > 3) | /* c:ffff88049b184000, u:0: 0000000020ca1ab0 + 0000000000000000 = 0000000020ca1ab0 > */ > 3) | /* sched-in counter ffff88049b184000, state: 1 > */ > 3) 2.605 us | } > 3) 9.714 us | } > 3) | perf_counter_task_tick() { > > the bug is that the '*/' comment closing text is printed in the next line > - that's not a linewrap, it happened like this in the trace. > > The reason is that the ftrace_printk did: > > ftrace_printk("c:%p, u:%d: %016Lx + %016Lx = %016Lx\n", > > the closing \n is pretty natural - especially for kernel hackers who might > just turn printk()s into ftrace_printk(), to embedd printouts in function > traces. So it would be nice if ftrace skipped over \n's when printing them > out as embedded C comments. > > Ingo > Yes I was afraid of the \n from the user for these comments. You're right, I will skip the newlines from the user. 2008/12/21 Ingo Molnar : > > * Ingo Molnar wrote: > >> btw., a graph-tracer buglet i noticed: > > another thing. I turned off all the options that come ahead of the 'meat' > of the trace data: > > # cat /debug/tracing/trace_options > print-parent nosym-offset nosym-addr noverbose noraw nohex nobin noblock > nostacktrace nosched-tree ftrace_printk noftrace_preempt nobranch annotate > nouserstacktrace nosym-userobj printk-msg-only nofuncgraph-overrun > nofuncgraph-cpu nofuncgraph-overhead nofuncgraph-proc > > but i still got the 'duration' field printed: > > # tracer: function_graph > # > # DURATION FUNCTION CALLS > # | | | | | > > 0.865 us | } > | alloc_page_vma() { > 0.295 us | get_vma_policy(); > 0.268 us | policy_zonelist(); > | __alloc_pages_internal() { > 0.257 us | __might_sleep(); > | get_page_from_freelist() { > > > i'd have expected to only see the flow of execution as it happens. > > Ingo > Strange. I will test that.