From: | "Jim C(dot) Nasby" <decibel(at)decibel(dot)org> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Tobias Brox <tobias(at)nordicbet(dot)com>, pgsql-performance(at)postgresql(dot)org |
Subject: | Re: "nice"/low priority Query |
Date: | 2005-08-02 17:25:50 |
Message-ID: | 20050802172550.GZ60019@decibel.org |
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Lists: | pgsql-performance |
On Tue, Aug 02, 2005 at 12:19:30PM -0400, Tom Lane wrote:
> Tobias Brox <tobias(at)nordicbet(dot)com> writes:
> > Is there any ways to give postgresql a hint that a
> > particular SQL call should be run at lower priority? Since every db
> > connection has a pid, I can manually run "renice" to scheduele it by the OS
> > - but of course I can't do it manually all the time.
>
> And it won't help you anyway, because renice only affects CPU priority
> not I/O scheduling ... which, by your description, is the real problem.
Actually, from what I've read 4.2BSD actually took priority into account
when scheduling I/O. I don't know if this behavior is still present in
FreeBSD or the like, though. So depending on the OS, priority could play
a role in determining I/O scheduling.
--
Jim C. Nasby, Database Consultant decibel(at)decibel(dot)org
Give your computer some brain candy! www.distributed.net Team #1828
Windows: "Where do you want to go today?"
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