From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933101AbZHDSHY (ORCPT ); Tue, 4 Aug 2009 14:07:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932989AbZHDSHX (ORCPT ); Tue, 4 Aug 2009 14:07:23 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123]:57699 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932978AbZHDSHX (ORCPT ); Tue, 4 Aug 2009 14:07:23 -0400 Date: Tue, 4 Aug 2009 14:07:21 -0400 (EDT) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Robert Richter cc: Ingo Molnar , LKML Subject: Re: [PATCH] ring-buffer: Fix advance of reader in rb_buffer_peek() In-Reply-To: <20090804164927.GZ14610@erda.amd.com> Message-ID: References: <1249044963-26878-1-git-send-email-robert.richter@amd.com> <20090804164927.GZ14610@erda.amd.com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 4 Aug 2009, Robert Richter wrote: > On 31.07.09 14:56:03, Robert Richter wrote: > > When calling rb_buffer_peek() from ring_buffer_consume() and a padding > > event is returned, the function rb_advance_reader() is called > > twice. This may lead to missing samples or under high workloads to the > > warning below. This patch fixes this. If a padding event is returned > > by rb_buffer_peek() it will be consumed by the calling function now. > > > > Also, I simplified some code in ring_buffer_consume(). > > > > ------------[ cut here ]------------ > > WARNING: at /dev/shm/.source/linux/kernel/trace/ring_buffer.c:2289 rb_advance_reader+0x2e/0xc5() > > Hardware name: Anaheim > > Modules linked in: > > Pid: 29, comm: events/2 Tainted: G W 2.6.31-rc3-oprofile-x86_64-standard-00059-g5050dc2 #1 > > Call Trace: > > [] ? rb_advance_reader+0x2e/0xc5 > > [] warn_slowpath_common+0x77/0x8f > > [] warn_slowpath_null+0xf/0x11 > > [] rb_advance_reader+0x2e/0xc5 > > [] ring_buffer_consume+0xa0/0xd2 > > [] op_cpu_buffer_read_entry+0x21/0x9e > > [] ? __find_get_block+0x4b/0x165 > > [] sync_buffer+0xa5/0x401 > > [] ? __find_get_block+0x4b/0x165 > > [] ? wq_sync_buffer+0x0/0x78 > > [] wq_sync_buffer+0x5b/0x78 > > [] worker_thread+0x113/0x1ac > > [] ? autoremove_wake_function+0x0/0x38 > > [] ? worker_thread+0x0/0x1ac > > [] kthread+0x88/0x92 > > [] child_rip+0xa/0x20 > > [] ? kthread+0x0/0x92 > > [] ? child_rip+0x0/0x20 > > ---[ end trace f561c0a58fcc89bd ]--- > > > > Cc: Steven Rostedt > > Cc: > > Signed-off-by: Robert Richter > > Steven, Ingo, > > should I apply the patch to my tree? Or does somebody of you wants to > apply it? I got a bug report and want to have it in a tree. I'll pull it in and start doing some of my own tests on it. Thanks! -- Steve