Re: [PERFORM] 9.4 -> 9.5 regression with queries through pgbouncer on RHEL 6

> 13 июня 2016 г., в 0:51, Andres Freund <andres(at)anarazel(dot)de> написал(а):
>
> Hi Vladimir,
>
> Thanks for these reports.
>
> On 2016-06-13 00:42:19 +0300, Vladimir Borodin wrote:
>> perf report -g -i pg9?_all.data >/tmp/pg9?_perf_report.txt
>
> Any chance you could redo the reports with --no-children --call-graph=fractal
> added? The mode that includes child overheads unfortunately makes the
> output hard to interpet/compare.

Of course. Not sure if that is important but I upgraded perf for that (because --no-children option was introduced in ~3.16), so perf record and perf report were done with different perf versions.

Also I’ve done the same test on same host (RHEL 6) but with 4.6 kernel/perf and writing perf data to /dev/shm for not loosing events. Perf report output is also attached but important thing is that the regression is not so significant:

root(at)pgload05g ~ # uname -r
4.6.0-1.el6.elrepo.x86_64
root(at)pgload05g ~ # cat /proc/sys/kernel/sched_autogroup_enabled
1
root(at)pgload05g ~ # /tmp/run.sh
RHEL 6 9.4 71634 0.893
RHEL 6 9.5 54005 1.185
RHEL 6 9.6 65550 0.976
root(at)pgload05g ~ # echo 0 >/proc/sys/kernel/sched_autogroup_enabled
root(at)pgload05g ~ # /tmp/run.sh
RHEL 6 9.4 73041 0.876
RHEL 6 9.5 60105 1.065
RHEL 6 9.6 67984 0.941
root(at)pgload05g ~ #

>
>> The results from pg9?_perf_report.txt are attached. Note that in all cases some events were lost, i.e.:
>>
>> root(at)pgload05g ~ # perf report -g -i pg94_all.data >/tmp/pg94_perf_report.txt
>> Failed to open [vsyscall], continuing without symbols
>> Warning:
>> Processed 537137 events and lost 7846 chunks!
>
> You can reduce the overhead by reducing the sampling frequency, e.g. by
> specifying -F 300.
>
> Greetings,
>
> Andres Freund
>
>
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