From: Tom Lane <tgl@sss.pgh.pa.us>
To: sumbry@revver.com
Cc: pgsql-performance@postgresql.org
Subject: Re: High Context-Switches on Linux 8.1.4 Server
Date: Mon, 07 Aug 2006 08:52:17 -0400
Message-ID: <19629.1154955137@sss.pgh.pa.us> (raw)
In-Reply-To: <44D6EDFA.4030802@revver.com>
References: <44D6EDFA.4030802@revver.com>
> We're seeing an average of 30,000 context-switches a sec. This problem
> was much worse w/8.0 and got bearable with 8.1 but slowly resurfaced.
Is this from LWLock or spinlock contention? strace'ing a few backends
could tell the difference: look to see how many select(0,...) you see
compared to semop()s. Also, how many of these compared to real work
(such as read/write calls)?
Do you have any long-running transactions, and if so does shutting
them down help? There's been some discussion about thrashing of the
pg_subtrans buffers being a problem, and that's mainly a function of
the age of the oldest open transaction.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, sumbry@revver.com
Subject: Re: High Context-Switches on Linux 8.1.4 Server
In-Reply-To: <19629.1154955137@sss.pgh.pa.us>
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