[Python-Dev] Help requested with Python 2.7 performance regression (original) (raw)

Gregory P. Smith greg at krypto.org
Thu Mar 2 15:59:52 EST 2017

We updated profile-opt to use the testsuite subset based on what distros had already been using for their training runs. As for the comment about the test suite not being good for training.... Mostly a myth. The test suite exercises the ceval loop well as well as things like re and json sufficiently to be a lot better than stupid workloads such as pybench (the previous default training run).

Room for improvement in training? Likely in some corners. But I have yet to see anyone propose any evidence based patch as a workload that reliably improves on anything for PGO over what we train with today.

-gpshead

On Thu, Mar 2, 2017, 1:12 AM INADA Naoki <songofacandy at gmail.com> wrote:

On Thu, Mar 2, 2017 at 4:07 AM, Antoine Pitrou <solipsis at pitrou.net> wrote: > On Wed, 1 Mar 2017 19:58:14 +0100 > Matthias Klose <doko at ubuntu.com> wrote: >> On 01.03.2017 18:51, Antoine Pitrou wrote: >> > As for the high level: what if the training set used for PGO in Xenial >> > has become skewed or inadequate? >> >> running the testsuite > > I did some tests a year or two ago, and running the whole test suite is > not a good idea, as coverage varies wildly from one functionality to the > other, so PGO will not infer the right information from it. You don't > get very good benchmark results from it. > > (for example, decimal has an extensive test suite which might lead PGO > to believe that code paths exercised by the decimal module are the > hottest ones) > > Regards > > Antoine. >

FYI, there are "profile-opt" make target. It uses subset of regrtest. https://github.com/python/cpython/blob/2.7/Makefile.pre.in#L211-L214 Does Ubuntu (and Debian) use it?

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