Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751524AbaK0NxO (ORCPT ); Thu, 27 Nov 2014 08:53:14 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39791 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751077AbaK0NxN (ORCPT ); Thu, 27 Nov 2014 08:53:13 -0500 Date: Thu, 27 Nov 2014 11:53:00 -0200 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: Jiri Olsa , linux-kernel@vger.kernel.org, Linus Torvalds , Andi Kleen , Corey Ashford , David Ahern , Frederic Weisbecker , Matt Fleming , Namhyung Kim , Paul Mackerras , Peter Zijlstra , Stephane Eranian Subject: Re: [PATCH] perf tools: Do not fail on processing out of order event Message-ID: <20141127135259.GI3808@redhat.com> References: <1417016371-30249-1-git-send-email-jolsa@kernel.org> <20141126154459.GD3808@redhat.com> <20141127105603.GA1987@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141127105603.GA1987@gmail.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.20 (2009-12-10) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Thu, Nov 27, 2014 at 11:56:03AM +0100, Ingo Molnar escreveu: > > * Arnaldo Carvalho de Melo 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 > > Arnaldo, I suppose the fix will go upstream via your tree, as a > pull request for v3.18 fixes? Right, I can do that. And I agree with the "expected" for events that are out of the current reordering window, i.e. we can't insert something into previous windows, so those are, humm, what would be a good name: stats->out_of_reordering_window, while stats->reordered, would be for events that were found out of order, but were successfully sorted as part of a flush operation, right? Also I'd drop that nr_ prefix, its a 'stat', so it probably is a "number", right? :-) - Arnaldo -- 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/