Re: Xeon vs Opteron - second revision - tests and questions - Mailing list pgsql-admin

From Tom Lane
Subject Re: Xeon vs Opteron - second revision - tests and questions
Date
Msg-id 20815.1131736317@sss.pgh.pa.us
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In response to Re: Xeon vs Opteron - second revision - tests and questions  (Marcin Giedz <marcin.giedz@eulerhermes.pl>)
Responses Re: Xeon vs Opteron - second revision - tests and questions
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Marcin Giedz <marcin.giedz@eulerhermes.pl> writes:
> However I still can see 'spikey' performance but  not as much as  before
> changes.  What can I do  more to  eliminate or smooth these spikes?

The spikes are certainly caused by checkpoints.  You can fool with the
checkpoint timing via checkpoint_segments and checkpoint_timeout.
Usually people put them as far apart as they can stand (the constraint
on this is mainly how long you'd like to wait for recovery after a
system crash, and how much disk space you can spare for WAL logs).
Increasing the bg_writer parameters can be expected to dampen the spikes
but not eliminate them completely.

            regards, tom lane

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