From: | Vlad <marchenko(at)gmail(dot)com> |
---|---|
To: | Merlin Moncure <mmoncure(at)gmail(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: High SYS CPU - need advise |
Date: | 2012-11-19 16:50:25 |
Message-ID: | CAKeSUqXc_2A4tPrAVJ-uSw1wdbt9_ZQprboLGiWL-xodt5=aZA@mail.gmail.com |
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Lists: | pgsql-general |
I just did a little experiment: extracted top four queries that were
executed the longest during stall times and launched pgbench test with 240
clients. Yet I wasn't able to put the server into a stall with that. Also
load average was hitting 120+, it was all user cpu, single digit % system.
The system remained pretty responsive (on a keypress), in contrary to when
high-sys-cpu stall happens, showing similar LA numbers.
This makes me think that there is probably a different (than ones I tried)
query or condition that is responsible for creating high-sys-cpu. Also,
from my limited knowledge of postgresql and kernel internals, this
experiment puts under question idea that linux scheduler might be the
corner stone....
Here is a longer log, first column is PID. High-sys-cpu stall happened
around 10:42:37
https://dl.dropbox.com/u/109778/postgresql-2012-11-19_103425-stripped.log
I'll try to put pgbouncer in place and repeat, also though this will take
longer time to setup.
-- Vlad
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