db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Knut Anders Hatlen <Knut.Hat...@Sun.COM>
Subject Re: [jira] Commented: (DERBY-2118) Change some boundary checks in ArrayInputStream to ASSERTs to improve performance
Date Tue, 05 Dec 2006 08:47:32 GMT
"Daniel John Debrunner (JIRA)" <jira@apache.org> writes:

> Daniel John Debrunner commented on DERBY-2118:
> ----------------------------------------------
>
> The tests pass for the clearLimit() changes and I performance
> changes for the select test ranging from -0.70% to +2.44%.
> Sometimes I seem to have trouble getting consistent numbers out of
> the test from DERBY-1961, even with an idle machine.

I am also seeing huge variations with the test from DERBY-1961. In
fact, I always see huge variations when I'm running performance tests
on Derby. My best guess so far is that the native code produced by the
hotspot compiler varies between runs (it uses statistics to decide
what to optimize and how to optimize it, so it might not be 100%
predictable). To eliminate the variation, I usually look at the
average of multiple runs.

-- 
Knut Anders

Mime
View raw message