From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755418Ab1BROwk (ORCPT ); Fri, 18 Feb 2011 09:52:40 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49416 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752417Ab1BROwh (ORCPT ); Fri, 18 Feb 2011 09:52:37 -0500 Date: Fri, 18 Feb 2011 15:52:19 +0100 From: Jiri Olsa To: rostedt@goodmis.org Cc: linux-kernel@vger.kernel.org, fweisbec@gmail.com, mingo@elte.hu Subject: [PATCHv2] trace: adding unstable sched clock note to the warning Message-ID: <20110218145219.GD2604@jolsa.brq.redhat.com> References: <1296649698-6003-1-git-send-email-jolsa@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1296649698-6003-1-git-send-email-jolsa@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org hi, warning "Delta way too big" warning might appear on a system with unstable shed clock right after the system is resumed and tracing was enabled during the suspend. Since it's not realy bug, and the unstable sched clock is working fast and reliable otherwise, Steven suggested to keep using the sched clock in any case and just to make note in the warning itself. v2 changes: - added CONFIG_HAVE_UNSTABLE_SCHED_CLOCK dependency wbr, jirka Signed-off-by: Jiri Olsa --- kernel/trace/ring_buffer.c | 12 ++++++++++-- 1 files changed, 10 insertions(+), 2 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index bd1c35a..37c4d3e 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2162,11 +2162,19 @@ rb_reserve_next_event(struct ring_buffer *buffer, if (likely(ts >= cpu_buffer->write_stamp)) { delta = diff; if (unlikely(test_time_stamp(delta))) { + int local_clock_stable = 1; +#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK + local_clock_stable = sched_clock_stable; +#endif WARN_ONCE(delta > (1ULL << 59), - KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n", + KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s", (unsigned long long)delta, (unsigned long long)ts, - (unsigned long long)cpu_buffer->write_stamp); + (unsigned long long)cpu_buffer->write_stamp, + local_clock_stable ? "" : + "If you just came from a suspend/resume,\n" + "please switch to the trace global clock:\n" + " echo global > /sys/kernel/debug/tracing/trace_clock\n"); add_timestamp = 1; } } -- 1.7.1