From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Olsa Subject: Re: [PATCH] perf/report: [RFC] Handling OOM in perf report Date: Tue, 9 Apr 2019 12:42:05 +0200 Message-ID: <20190409104205.GB29688@krava> References: <20190401142000.17679-1-tmricht@linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190401142000.17679-1-tmricht@linux.ibm.com> Sender: linux-kernel-owner@vger.kernel.org To: Thomas Richter Cc: linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, acme@kernel.org, brueckner@linux.vnet.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com List-Id: linux-perf-users.vger.kernel.org On Mon, Apr 01, 2019 at 04:20:00PM +0200, Thomas Richter wrote: SNIP > perf_session__process_event() returns to its caller, where -ENOMEM is > changed to -EINVAL and processing stops: > > if ((skip = perf_session__process_event(session, event, head)) < 0) { > pr_err("%#" PRIx64 " [%#x]: failed to process type: %d\n", > head, event->header.size, event->header.type); > err = -EINVAL; > goto out_err; > } > > This occured in the FINISHED_ROUND event when it has to process some > 10000 entries and ran out of memory. > > I understand that my perf.data file might just be too big, but I would > like to see some error message indicating OOM error instead of > processing failure of a unrelated event. you can limit the size of the report queue via ~/.perfconfig file: [report] queue-size=1M above should use only 1M for the queue management data the data for sample still get allocated thought.. but it could help > > However this patch just does what the pr_debug() statement indicates, > the event is skipped and processing continues. > But at least the root cause is indicated and also shows up in the > GUI. > > Signed-off-by: Thomas Richter > --- > tools/perf/builtin-report.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c > index 4054eb1f98ac..7a27b815f7a8 100644 > --- a/tools/perf/builtin-report.c > +++ b/tools/perf/builtin-report.c > @@ -283,8 +283,13 @@ static int process_sample_event(struct perf_tool *tool, > al.map->dso->hit = 1; > > ret = hist_entry_iter__add(&iter, &al, rep->max_stack, rep); > - if (ret < 0) > + if (ret < 0) { > pr_debug("problem adding hist entry, skipping event\n"); > + if (ret == -ENOMEM) { > + pr_err("Running out of memory\n"); > + ret = 0; > + } > + } I think we can propagate the error completely (like below), and even warn about ENOMEM specificaly but I think we should bail out in case of ENOMEM, because the data are incomplete and misleading jirka --- diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index b17f1c9bc965..eea247a26ad8 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -1933,7 +1933,7 @@ reader__process_events(struct reader *rd, struct perf_session *session, pr_err("%#" PRIx64 " [%#x]: failed to process type: %d\n", file_offset + head, event->header.size, event->header.type); - err = -EINVAL; + err = skip; goto out; }