Performance patch for AIX system api support of sun.nio.ch.FileChannelImpl.transferTo0()
Alan.Bateman at oracle.com
Thu Oct 20 01:07:10 PDT 2011
Charles Lee wrote:
> Thanks Alan. Any requirements for performance patches to contribute?
> Test case? Test result?
Speaking generally, when working on a performance fix (or any fix for
that matter) it's always good to understand the test coverage for the
area that you are changing. The math area is a good example where
performance work in 7 required extending the test coverage to give
confidence that performance work didn't cause any correctness issues.
There are examples in other areas too. When fixing bugs then the rule is
that tests should be added (or existing tests updated) to cover the
scenario that is being fixed. However there are cases, including
performance, where it's not feasible or doesn't make sense to write an
automated test. Tests need to run quickly so we wouldn't check in a test
that takes an hour to demonstrate a bug for example. Also it's worth
keeping existing tests in mind to avoid duplicating existing tests. With
performance tests then it's as I was saying in the first mail, the jdk
repository isn't really the best place for them in my view. It's fine to
push tests that print results that we can run manually in a controlled
environment (we have several examples of this) but we can't have tests
that fail if they think that the performance isn't as expected. At some
point it would it great if OpenJDK could get a repository and framework
for micro benchmarks and maybe larger performance tests but that's a
bigger discussion and not really something for this list.
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