From: | Josh Krupka <jkrupka(at)gmail(dot)com> |
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To: | Johnny Tan <johnnydtan(at)gmail(dot)com> |
Cc: | Charles Gomes <charlesrg(at)outlook(dot)com>, Strahinja Kustudić <strahinjak(at)nordeus(dot)com>, Kevin Grittner <kgrittn(at)ymail(dot)com>, "ac(at)hsk(dot)hk" <ac(at)hsk(dot)hk>, Alex Kahn <alex(at)paperlesspost(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: postgresql.conf recommendations |
Date: | 2013-02-07 17:49:36 |
Message-ID: | CAB6McgUE0Lv-KeOnmrhhds9+O1YQ69Gz-JD0JeCCQwD7fRfFUA@mail.gmail.com |
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Lists: | pgsql-performance |
Just as an update from my angle on the THP side... I put together a
systemtap script last night and so far it's confirming my theory (at least
in our environment). I want to go through some more data and make some
changes on our test box to see if we can make it go away before declaring
success - it's always possible two problems are intertwined or that the THP
thing is only showing up because of the *real* problem... you know how it
goes.
Basically the systemtap script does this:
- probes the compaction function
- keeps track of the number of calls to it and aggregate time spent in it
by process
- at the end spit out the collected info.
So far when I run the script for a short period of time that I know THP
compactions are happening, I have been able to match up the compaction
duration collected via systemtap with a query in the pg logs that took that
amount of time or slightly longer (as expected). A lot of these are only a
second or so, so I haven't been able to catch everything, but at least the
data I am getting is consistent.
Will be interested to see what you find Johnny.
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