Heikki Linnakangas wrote:
Jeremy Kerr wrote:
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 .

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.

Based on this benchmark, I don't think this patch is worth it..

what exactly is getting graphed here - is the what sysbench reports as transactions/s or the operations/queries per second? if yes it is important to notice that sysnbench by default executes multiple queries per transaction and and several different kind of queries. Only some of those queries have bcTruelen() showing up on top of the profile.



Stefan

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