From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755949Ab1CGKpd (ORCPT ); Mon, 7 Mar 2011 05:45:33 -0500 Received: from mx1.redhat.com ([209.132.183.28]:31814 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755883Ab1CGKpZ (ORCPT ); Mon, 7 Mar 2011 05:45:25 -0500 Date: Mon, 7 Mar 2011 11:45:13 +0100 From: Jiri Olsa To: rostedt@goodmis.org Cc: linux-kernel@vger.kernel.org, fweisbec@gmail.com, mingo@elte.hu Subject: Re: [PATCHv2] trace: adding unstable sched clock note to the warning Message-ID: <20110307104513.GB3661@jolsa.redhat.com> References: <1296649698-6003-1-git-send-email-jolsa@redhat.com> <20110218145219.GD2604@jolsa.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110218145219.GD2604@jolsa.brq.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, any feedback? thanks, jirka On Fri, Feb 18, 2011 at 03:52:19PM +0100, Jiri Olsa wrote: > 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 > -- > 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/