Re: Trivial HugeTLB Benchmark - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Trivial HugeTLB Benchmark
Date
Msg-id 22726.1173032046@sss.pgh.pa.us
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In response to Trivial HugeTLB Benchmark  (Ryan Cumming <ryan.cumming@neverbluemedia.com>)
Responses Re: Trivial HugeTLB Benchmark  (Ryan Cumming <ryan.cumming@neverbluemedia.com>)
List pgsql-hackers
Ryan Cumming <ryan.cumming@neverbluemedia.com> writes:
> I ran each pgbench after a fresh reboot. I used 85 huge pages reserved at boot for the huge page test, and none for
thenormal shared memory test.
 

> Normal shared memory:
> -bash-3.00$ pgbench -c 5 -t 10000
> starting vacuum...end.
> transaction type: TPC-B (sort of)
> scaling factor: 1
> number of clients: 5
> number of transactions per client: 10000
> number of transactions actually processed: 50000/50000
> tps = 1669.009344 (including connections establishing)
> tps = 1669.941756 (excluding connections establishing)

If you did this only once, the results are not really trustworthy;
you need to average several similar runs before you can have much
confidence.  pgbench's inter-run variation is usually upwards of 10%,
so trying to draw conclusions about half-percentage-point differences
without averaging is a waste of time.

Also, if scaling factor < number of clients then what you're mostly
measuring is update-contention behavior.  Try it with -s 10 and -c 5;
and don't forget to reinitialize the database for each run of tests
to be sure it's fair.
        regards, tom lane


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