Horton

Re: wal_buffers, redux

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Jeff Janes <jeff.janes@gmail.com>
Cc: pgsql-hackers@postgresql.org
Date: 2012-03-13T19:48:32Z
Lists: pgsql-hackers 
On Mon, Mar 12, 2012 at 4:45 PM, Jeff Janes <jeff.janes@gmail.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
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company