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

13 июня 2016 г., в 21:58, Vladimir Borodin <root@simply.name> написал(а):

13 июня 2016 г., в 0:51, Andres Freund <andres@anarazel.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.

<pg94_perf_report.txt.gz>

<pg95_perf_report.txt.gz>

<pg96_perf_report.txt.gz>

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@pgload05g ~ # uname -r

4.6.0-1.el6.elrepo.x86_64

root@pgload05g ~ # cat /proc/sys/kernel/sched_autogroup_enabled

1

root@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@pgload05g ~ # echo 0 >/proc/sys/kernel/sched_autogroup_enabled

root@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@pgload05g ~ #

<pg96_perf_report_4.6.txt.gz>

<pg95_perf_report_4.6.txt.gz>

<pg94_perf_report_4.6.txt.gz>

The results from pg9?_perf_report.txt are attached. Note that in all cases some events were lost, i.e.:

root@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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