From: Ingo Molnar <mingo@kernel.org>
To: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>,
linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Andi Kleen <ak@linux.intel.com>,
Corey Ashford <cjashfor@linux.vnet.ibm.com>,
David Ahern <dsahern@gmail.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Matt Fleming <matt.fleming@intel.com>,
Namhyung Kim <namhyung@kernel.org>,
Paul Mackerras <paulus@samba.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH] perf tools: Do not fail on processing out of order event
Date: Thu, 27 Nov 2014 11:56:03 +0100 [thread overview]
Message-ID: <20141127105603.GA1987@gmail.com> (raw)
In-Reply-To: <20141126154459.GD3808@redhat.com>
* Arnaldo Carvalho de Melo <acme@redhat.com> wrote:
> Em Wed, Nov 26, 2014 at 04:39:31PM +0100, Jiri Olsa escreveu:
> > Linus reported perf report command being interrupted due to
> > processing of 'out of order' event, with following error:
> >
> > Timestamp below last timeslice flush
> > 0x5733a8 [0x28]: failed to process type: 3
> >
> > I could reproduce the issue and in my case it was caused by one
> > CPU (mmap) being behind during record and userspace mmap reader
> > seeing the data after other CPUs data were already stored.
> >
> > It'd be nice to find the source of this hiccup, meanwhile I'm
> > submitting change that does not kill the processing, but only
> > tracks the number of out of order events and warn user.
>
> Works, for me, thanks for the fast response!
Thanks Jiri!
> > --- a/tools/perf/util/session.c
> > +++ b/tools/perf/util/session.c
> > @@ -533,15 +533,11 @@ int perf_session_queue_event(struct perf_session *s, union perf_event *event,
> > return -ETIME;
> >
> > if (timestamp < oe->last_flush) {
> > - WARN_ONCE(1, "Timestamp below last timeslice flush\n");
> > -
> > - pr_oe_time(timestamp, "out of order event");
> > + pr_oe_time(timestamp, "out of order event\n");
> > pr_oe_time(oe->last_flush, "last flush, last_flush_type %d\n",
> > oe->last_flush_type);
> >
> > - /* We could get out of order messages after forced flush. */
> > - if (oe->last_flush_type != OE_FLUSH__HALF)
> > - return -EINVAL;
> > + s->stats.nr_unordered_events++;
Btw., in the forced flush case we'll get out of order events that
are 'expected'. Shouldn't we count them separately and not warn
about them, or so?
> > + if (session->stats.nr_unordered_events != 0) {
> > + ui__warning("%u out of order events recorded.\n",
> > + session->stats.nr_unordered_events);
> > + }
Nit: I'd suggest keeping the message printout on a single line:
if (session->stats.nr_unordered_events != 0) {
ui__warning("%u out of order events recorded.\n", session->stats.nr_unordered_events);
as IMHO the cure for this col80 linebreak checkpatch warning is
worse than the disease! :-)
Barring those details:
Acked-by: Ingo Molnar <mingo@kernel.org>
Arnaldo, I suppose the fix will go upstream via your tree, as a
pull request for v3.18 fixes?
Thanks,
Ingo
next prev parent reply other threads:[~2014-11-27 10:56 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-26 15:39 [PATCH] perf tools: Do not fail on processing out of order event Jiri Olsa
2014-11-26 15:44 ` Arnaldo Carvalho de Melo
2014-11-27 10:56 ` Ingo Molnar [this message]
2014-11-27 12:54 ` Jiri Olsa
2014-11-27 13:54 ` Arnaldo Carvalho de Melo
2014-11-27 13:53 ` Arnaldo Carvalho de Melo
2014-11-27 14:07 ` Jiri Olsa
2014-11-27 14:16 ` Arnaldo Carvalho de Melo
2014-11-27 14:23 ` Jiri Olsa
2014-11-27 14:45 ` Arnaldo Carvalho de Melo
2014-11-27 19:44 ` Andi Kleen
2014-12-09 10:16 ` [tip:perf/urgent] perf session: " tip-bot for Jiri Olsa
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