Ok, looks like the FreeBSD community is interested in PostgreSQL
performance, or at least enough to investigate it.

Anyone here have experience hacking on FreeBSD?

----- Forwarded message from Kris Kennaway <kris@obsecurity.org> -----

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Date: Sun, 25 Feb 2007 19:22:35 -0500
From: Kris Kennaway <kris@obsecurity.org>
To: current@FreeBSD.org
User-Agent: Mutt/1.4.2.2i
Cc: performance@FreeBSD.org
Subject: Anyone interested in improving postgresql scaling?
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If so, then your task is the following:

Make SYSV semaphores less dumb about process wakeups. Currently
whenever the semaphore state changes, all processes sleeping on the
semaphore are woken, even if we only have released enough resources
for one waiting process to claim. i.e. there is a thundering herd
wakeup situation which destroys performance at high loads. Fixing
this will involve replacing the wakeup() calls with appropriate
amounts of wakeup_one().

Kris

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--
Jim C. Nasby, Database Architect decibel@decibel.org
Give your computer some brain candy! www.distributed.net Team #1828

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"Jim C. Nasby" <decibel@decibel.org> writes:
> Ok, looks like the FreeBSD community is interested in PostgreSQL
> performance, or at least enough to investigate it.

I think this guy is barking up the wrong tree though, because we don't
ever have multiple processes sleeping on the same sema. Not that
there's anything wrong with his proposal, but it doesn't affect Postgres.

regards, tom lane

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