From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Kris Kennaway <kris(at)obsecurity(dot)org> |
Cc: | Mark Kirkwood <markir(at)paradise(dot)net(dot)nz>, current(at)FreeBSD(dot)org, performance(at)FreeBSD(dot)org, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Anyone interested in improving postgresql scaling? |
Date: | 2007-04-10 21:36:17 |
Message-ID: | 3721.1176240977@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Kris Kennaway <kris(at)obsecurity(dot)org> writes:
> I have not studied the exact code path, but there are indeed multiple
> wakeups happening from the semaphore code (as many as the number of
> active postgresql processes). It is easy to instrument
> sleepq_broadcast() and log them when they happen.
There are certainly cases where Postgres will wake up a number of
processes in quick succession, but that should happen from a separate
semop() kernel call, on a different semaphore, for each such process.
If there's really multiple processes being released by the same semop()
then there's a bug we need to look into (or maybe it's a kernel bug?).
Anyway I'd be interested to know what the test case is, and which PG
version you were testing.
regards, tom lane
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