From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754602AbbFKOGX (ORCPT ); Thu, 11 Jun 2015 10:06:23 -0400 Received: from mail.kernel.org ([198.145.29.136]:36095 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752111AbbFKOGT (ORCPT ); Thu, 11 Jun 2015 10:06:19 -0400 Date: Thu, 11 Jun 2015 11:06:14 -0300 From: Arnaldo Carvalho de Melo To: kan.liang@intel.com Cc: linux-kernel@vger.kernel.org, ying.huang@intel.com, andi@firstfloor.org Subject: Re: [PATCH 1/1] perf,tools: add time out to force stop endless mmap processing Message-ID: <20150611140614.GC2696@kernel.org> References: <1433922364-22580-1-git-send-email-kan.liang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1433922364-22580-1-git-send-email-kan.liang@intel.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Wed, Jun 10, 2015 at 03:46:04AM -0400, kan.liang@intel.com escreveu: > perf top reads all threads' /proc/xxx/maps. If there is any threads > which generating a keeping growing huge /proc/xxx/maps, perf will do > infinite loop in perf_event__synthesize_mmap_events. > This patch fixes this issue by adding a time out to force stop this kind > of endless mmap processing. > > Reported-by: Huang, Ying > Signed-off-by: Kan Liang So we will silently stop processing those events? We will make progress, no doubt, but I think the user needs to be warned about this situation, so that later on when/if samples for those maps appear and don't get resolved at least we will know that this is the reason. - Arnaldo > --- > tools/perf/util/event.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c > index 793b150..0df7f2a9 100644 > --- a/tools/perf/util/event.c > +++ b/tools/perf/util/event.c > @@ -213,6 +213,8 @@ static int perf_event__synthesize_fork(struct perf_tool *tool, > return 0; > } > > +#define MMAP_TIMEOUT (50 * 1000000ULL) > + > int perf_event__synthesize_mmap_events(struct perf_tool *tool, > union perf_event *event, > pid_t pid, pid_t tgid, > @@ -222,6 +224,7 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, > { > char filename[PATH_MAX]; > FILE *fp; > + unsigned long long t; > int rc = 0; > > if (machine__is_default_guest(machine)) > @@ -240,6 +243,7 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, > } > > event->header.type = PERF_RECORD_MMAP2; > + t = rdclock(); > > while (1) { > char bf[BUFSIZ]; > @@ -250,7 +254,8 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, > size_t size; > ssize_t n; > > - if (fgets(bf, sizeof(bf), fp) == NULL) > + if ((fgets(bf, sizeof(bf), fp) == NULL) || > + ((rdclock() - t) > MMAP_TIMEOUT)) > break; > > /* ensure null termination since stack will be reused. */ > -- > 1.8.3.1