From: | Andres Freund <andres(at)anarazel(dot)de> |
---|---|
To: | Greg Stark <stark(at)mit(dot)edu> |
Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Pgbench performance tuning? |
Date: | 2016-08-04 18:20:37 |
Message-ID: | 20160804182037.nqsqix4yr7abdjop@alap3.anarazel.de |
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Lists: | pgsql-hackers |
On 2016-08-04 19:15:43 +0100, Greg Stark wrote:
> On Thu, Aug 4, 2016 at 6:53 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> > What's the config? Version? What activity does pidstat -d -l indicate?
> > How much WAL was generated?
>
> I know the specifics matter but I was also trying to avoid dumping too
> much into the email.
>
> The shared buffers is set to 16384 (128MB). Otherwise it's a default
> config (For 9.4 and before I set checkpoint_segments to 32 as well).
Well, with 128MB I don't find that a very surprising result. You're
going to push data out to disk constantly. Given the averaged random
access pattern of pgbench that's not really something that interesting.
> Never seen pidstat before but pidstat -d looks like it prints very
> similar output to the iostat output I was gathering already. There's
> nothing else running on the machine.
The question is which backends are doing the IO.
Greetings,
Andres Freund
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