From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754311Ab1CKJwB (ORCPT ); Fri, 11 Mar 2011 04:52:01 -0500 Received: from hera.kernel.org ([140.211.167.34]:38619 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751838Ab1CKJwA (ORCPT ); Fri, 11 Mar 2011 04:52:00 -0500 Date: Fri, 11 Mar 2011 09:51:44 GMT From: tip-bot for Jiri Olsa Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, rostedt@goodmis.org, tglx@linutronix.de, jolsa@redhat.com Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, rostedt@goodmis.org, tglx@linutronix.de, jolsa@redhat.com In-Reply-To: <20110218145219.GD2604@jolsa.brq.redhat.com> References: <20110218145219.GD2604@jolsa.brq.redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] tracing: Explain about unstable clock on resume with ring buffer warning Message-ID: Git-Commit-ID: 31274d72f01604f4b02d933b4f3cac84d2c201fd X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Fri, 11 Mar 2011 09:51:44 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 31274d72f01604f4b02d933b4f3cac84d2c201fd Gitweb: http://git.kernel.org/tip/31274d72f01604f4b02d933b4f3cac84d2c201fd Author: Jiri Olsa AuthorDate: Fri, 18 Feb 2011 15:52:19 +0100 Committer: Steven Rostedt CommitDate: Thu, 10 Mar 2011 10:34:47 -0500 tracing: Explain about unstable clock on resume with ring buffer warning The "Delta way too big" warning might appear on a system with a unstable shed clock right after the system is resumed and tracing was enabled at time of suspend. Since it's not realy a 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 #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK Signed-off-by: Jiri Olsa LKML-Reference: <20110218145219.GD2604@jolsa.brq.redhat.com> Signed-off-by: Steven Rostedt --- 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 3237d96..db7b439 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2172,11 +2172,19 @@ 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; } }