Date: Tue, 10 Apr 2007 17:36:17 -0400 From: Tom Lane <tgl@sss.pgh.pa.us> To: Kris Kennaway <kris@obsecurity.org> Cc: performance@FreeBSD.org, current@FreeBSD.org, Mark Kirkwood <markir@paradise.net.nz>, pgsql-hackers <pgsql-hackers@postgresql.org> Subject: Re: [HACKERS] Anyone interested in improving postgresql scaling? Message-ID: <3721.1176240977@sss.pgh.pa.us> In-Reply-To: <20070410184304.GB44123@xor.obsecurity.org> References: <20070226002234.GA80974@xor.obsecurity.org> <461B69C0.4060707@paradise.net.nz> <20070410184304.GB44123@xor.obsecurity.org>
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Kris Kennaway <kris@obsecurity.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 lanehome | help
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