On 4/9/19 12:42 PM, Jiri Olsa wrote:
> 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 <tmri...@linux.ibm.com>
>> ---
>> 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;
> }
>
>
Above patch does not help, you simply return -ENOMEM instead of -EINVAL and
processing
stops with no indication that perf ran out of memory. Bailing out in this case
is ok.
I am fine with your patch, as long as it gives a reason why processing stopped.
In the GUI it shows on the bottom line the reason:
0xf4198 [0x8]: failed to process type: 68 [Cannot allocate memory]
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index b17f1c9bc965..e89716175588 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1930,10 +1930,10 @@ reader__process_events(struct reader *rd, struct
perf_session *session,
if (size < sizeof(struct perf_event_header) ||
(skip = rd->process(session, event, file_pos)) < 0) {
- pr_err("%#" PRIx64 " [%#x]: failed to process type: %d\n",
+ pr_err("%#" PRIx64 " [%#x]: failed to process type: %d [%s]\n",
file_offset + head, event->header.size,
- event->header.type);
- err = -EINVAL;
+ event->header.type, strerror(-skip));
+ err = skip;
goto out;
}
[root@m35lp76 perf]#
--
Thomas Richter, Dept 3252, IBM s390 Linux Development, Boeblingen, Germany
--
Vorsitzender des Aufsichtsrats: Matthias Hartmann
Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB
243294
