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Re: [PERFORM] Help with tuning this query (with

From: Greg Stark <gsstark(at)mit(dot)edu>
To: "Dave Held" <dave(dot)held(at)arrayservicesgrp(dot)com>
Cc: "Greg Stark" <gsstark(at)mit(dot)edu>,"John A Meinel" <john(at)arbash-meinel(dot)com>,"Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>,"Magnus Hagander" <mha(at)sollentuna(dot)net>,"Ken Egervari" <ken(at)upfactor(dot)com>,<pgsql-performance(at)postgresql(dot)org>,<pgsql-hackers-win32(at)postgresql(dot)org>
Subject: Re: [PERFORM] Help with tuning this query (with
Date: 2005-03-07 23:15:29
Message-ID: 87br9v9hf2.fsf@stark.xeocode.com (view raw or flat)
Thread:
Lists: pgsql-hackers-win32pgsql-performance
"Dave Held" <dave(dot)held(at)arrayservicesgrp(dot)com> writes:

> > What would be really neato would be to use the rtdsc (sp?) or 
> > equivalent assembly instruction where available. Most processors
> > provide such a thing and it would give much lower overhead and much
> > more accurate answers.
> > 
> > The main problem I see with this would be on multi-processor
> > machines. (QueryPerformanceCounter does work properly on 
> > multi-processor machines, right?)
> 
> I believe QueryPerformanceCounter() already does this.

This would be a good example of why selectively quoting the part of the
message to which you're responding to is more useful than just blindly echoing
my message back to me.

Already does what? 

Use rtdsc? In which case using it would be a mistake. Since rtdsc doesn't work
across processors. And using it via QueryPerformanceCounter would be a
non-portable approach to using rtdsc. Much better to devise a portable
approach that works on any architecture where something equivalent is
available.

Or already works on multi-processor machines? In which case, uh, ok.


-- 
greg


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