On Wed, 1 Mar 2017 12:28:24 -0500 Barry Warsaw <barry@python.org> wrote:
Louis (Cc'd here) has done a ton of work to measure and analyze the problem, but we've more or less hit a roadblock, so we're taking the issue public to see if anybody on this mailing list has further ideas. A detailed analysis is available in this Google doc:
https://docs.google.com/document/d/1zrV3OIRSo99fd2Ty4YdGk_scmTRDmVauBprKL8ei...
The document should be public for comments and editing.
I may be misunderstanding the document, but this lacks at least a comparison of the *same* interpreter version with different compiler versions. As for the high level: what if the training set used for PGO in Xenial has become skewed or inadequate? Just a thought, as it would imply that PGO+LTO uses wrong information for code placement and other optimizations. Regards Antoine.