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Re: Calling conventions

From: Matthew Wakeling <matthew(at)flymine(dot)org>
To: Peter Eisentraut <peter_e(at)gmx(dot)net>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Calling conventions
Date: 2009-07-17 16:09:22
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
On Fri, 17 Jul 2009, Peter Eisentraut wrote:
> On Friday 17 July 2009 16:40:40 Matthew Wakeling wrote:
>> I'm considering rewriting a postgres extension (GiST index bioseg) to make
>> it use version 1 calling conventions rather than version 0.
>> Does anyone have any ideas/opinions/statistics on what the performance
>> difference is between the two calling conventions?
> Version 1 is technically slower if you count the number of instructions, but
> considering that everyone else, including PostgreSQL itself, uses version 1,
> and version 0 has been deprecated for years and will break on some
> architectures, it should be a no-brainer.

Is that so?

Well, here's my problem. I have GiST index type called bioseg. I have 
implemented the very same algorithm in both a Postgres GiST extension and 
as a standalone Java program. In general, the standalone Java program 
performs about 100 times faster than Postgres when running a large 
index-based nested loop join.

I profiled Postgres a few weeks back, and found a large amount of time 
being spent in fmgr_oldstyle.

On Thu, 11 Jun 2009, Tom Lane wrote:
> Matthew Wakeling <matthew(at)flymine(dot)org> writes:
>> Anyway, running opannotate seems to make it clear that time *is* spent in
>> the gistnext function, but almost all of that is in children of the
>> function. Lots of time is actually spent in fmgr_oldstyle though.
> So it'd be worth converting your functions to V1 style.

Are you saying that it would spend just as much time in fmgr_newstyle (or 
whatever the correct symbol is)?


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 very selective about who its friends are.                 -- Kyle Hearn

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