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Re: [PATCH] backend: compare word-at-a-time in bcTruelen - Mailing list pgsql-hackers

From Jeremy Kerr
Subject Re: [PATCH] backend: compare word-at-a-time in bcTruelen
Date
Msg-id 200906171731.07149.jk@ozlabs.org
Whole thread Raw
In response to Re: [PATCH] backend: compare word-at-a-time in bcTruelen  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: [PATCH] backend: compare word-at-a-time in bcTruelen  (Gurjeet Singh <singh.gurjeet@gmail.com>)
Re: [PATCH] backend: compare word-at-a-time in bcTruelen  (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>)
Re: [PATCH] backend: compare word-at-a-time in bcTruelen  (Stefan Kaltenbrunner <stefan@kaltenbrunner.cc>)
[PATCH] backend: compare word-at-a-time in bcTruelen  (Jeremy Kerr <jk@ozlabs.org>)
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Hi all,

> Speaking of which, what about some performance numbers?

OK, benchmarks done:
http://ozlabs.org/~jk/projects/db/data/postgres.bcTruelen/

Summary: small increase in performance (~1-2% on my machine), at about 
1.5 standard deviations from the mean. Profiles show a decent drop in 
hits within bcTruelen.

However: Sysbench seems to be quite heavy with the fixed-width char 
types, so may end up calling bcTruelen more than most workloads. Would 
be nice to get some x86 numbers too, but I don't have a suitable machine 
here.

So: The increase in performance is positive on this workload, albeit 
fairly minor. Downside is increased code complexity.

Will re-send the patch once I work out how to get git to create a 
context diff...

Cheers,


Jeremy

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