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Message-ID: <44C0EBE5.8010508@aeccom.com>
Date: Fri, 21 Jul 2006 16:59:49 +0200
From: Sven Geisler <sgeisler@aeccom.com>
Organization: AEC/communications GmbH
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To: Tom Lane <tgl@sss.pgh.pa.us>
CC: Robert Lor <Robert.Lor@Sun.COM>, Tatsuo Ishii <ishii@sraoss.co.jp>,
	pgsql-hackers@postgresql.org,  pgsql-performance@postgresql.org
Subject: Re: [HACKERS] Sun Donated a Sun Fire T2000 to the PostgreSQL
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Hi,

Tom Lane schrieb:
> Robert Lor <Robert.Lor@Sun.COM> writes:
>> I ran pgbench and fired up a DTrace script using the lwlock probes we've 
>> added, and it looks like BufMappingLock is the most contended lock, but  
>> CheckpointStartLocks are held for longer duration!
> 
> Those numbers look a bit suspicious --- I'd expect to see some of the
> LWLocks being taken in both shared and exclusive modes, but you don't
> show any such cases.  You sure your script is counting correctly?
> Also, it'd be interesting to count time spent holding shared lock
> separately from time spent holding exclusive.

Is there a test case which shows the contention for this full cached
tables? It would be nice to have measurable numbers like context
switches and queries per second.

Sven.