From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Kenneth Marshall <ktm(at)is(dot)rice(dot)edu> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Wierd context-switching issue on Xeon |
Date: | 2004-04-22 01:45:54 |
Message-ID: | 17856.1082598354@sss.pgh.pa.us |
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Lists: | pgsql-performance |
Kenneth Marshall <ktm(at)is(dot)rice(dot)edu> writes:
> If the context swap storm derives from LWLock contention, maybe using
> a random order to assign buffer locks in buf_init.c would prevent
> simple adjacency of buffer allocation to cause the storm.
Good try, but no cigar ;-). The test cases I've been looking at take
only shared locks on the per-buffer locks, so that's not where the
context swaps are coming from. The swaps have to be caused by the
BufMgrLock, because that's the only exclusive lock being taken.
I did try increasing the allocated size of the spinlocks to 128 bytes
to see if it would do anything. It didn't ...
regards, tom lane
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