Re: Checkpoint cost, looks like it is WAL/CRC

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: josh(at)agliodbs(dot)com
Cc: Postgres Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Checkpoint cost, looks like it is WAL/CRC
Date: 2005-07-19 20:06:57
Message-ID: 9193.1121803617@sss.pgh.pa.us
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Josh Berkus <josh(at)agliodbs(dot)com> writes:
> So, now that we know what the performance bottleneck is, how do we fix it?

Josh, I see that all of those runs seem to be using wal_buffers = 8.
Have you tried materially increasing wal_buffers (say to 100 or 1000)
and/or experimenting with different wal_sync_method options since we
fixed the bufmgrlock problem? I am wondering if the real issue is
WAL buffer contention or something like that.

It would also be useful to compare these runs to runs with fsync = off,
just to see how the performance changes.

regards, tom lane

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