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Re: wal_buffers, redux

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: wal_buffers, redux
Date: 2012-03-13 19:48:32
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
On Mon, Mar 12, 2012 at 4:45 PM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
> Rerunning all 4 benchmarks (both 16MB and 32MB wal_buffers on both
> machines) with fsync=off (as well as synchronous_commit=off still)
> might help clarify things.

I reran the 32-client benchmark on the IBM machine with fsync=off and got this:

32MB: tps = 26809.442903 (including connections establishing)
16MB: tps = 26651.320145 (including connections establishing)

That's a speedup of nearly a factor of two, so clearly fsync-related
stalls are a big problem here, even with wal_buffers cranked up
through the ceiling.

Robert Haas
The Enterprise PostgreSQL Company

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