Skip site navigation (1)Skip section navigation (2)
Date:      Sat, 12 Mar 2022 03:16:32 +0000
From:      bugzilla-noreply@freebsd.org
To:        python@FreeBSD.org
Subject:   [Bug 262495] lang/python*: add option PGO and enable by default, add LTO option to python27 and enable by default
Message-ID:  <bug-262495-21822-YxO4M39r7I@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-262495-21822@https.bugs.freebsd.org/bugzilla/>
References:  <bug-262495-21822@https.bugs.freebsd.org/bugzilla/>

next in thread | previous in thread | raw e-mail | index | archive | help
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D262495

Kubilay Kocak <koobs@FreeBSD.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |koobs@FreeBSD.org

--- Comment #1 from Kubilay Kocak <koobs@FreeBSD.org> ---
Created attachment 232397
  --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D232397&action=
=3Dedit
clang as cc detection for pgo

Thanks Piotr

What is the nature of the dependence on PGO for LTO?=20

If this is only a consequence of the 'optimization' option 'needing' both [=
1],
we shouldn't couple ourselves to that option.

Also I don't believe we should default to PGO builds, particularly at such =
an
early stage, as the profiling and optimizations instrumentation on the offi=
cial
package build hardware, will only be specific to that hardware, and may not=
 be
appropriate for, is unlikely to be, or may result in performance regressions
on, any other (user) hardware.

There was also an issue identified during my testing  with Python not detec=
ting
cc (clang) for PGO [2], which requires and additional '*)' case for default=
ing
to 'clang style PGO'. There may be alternate ways to address this, and this=
 was
not tested in the gcc case. We wont want to carry local patches in the long
term either, so working with upstream to resolve this is important.

We'll also want to test and confirm QA across all supported freebsd version=
s,
archs, and toolchains (gcc included) explicitly, and include Python's test
suite in that QA. At a minimum the test failure delta should not change.

Unfortunately, a successful build alone is insufficient for LTO/PGO, and th=
ere
are many results for LTO/PGO Python segfaults and other issues at runtime o=
ut
there.

[1] https://bugs.python.org/issue29766
[2] https://464982.bugs.gentoo.org/attachment.cgi?id=3D344902

--=20
You are receiving this mail because:
You are the assignee for the bug.
You are on the CC list for the bug.=



Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?bug-262495-21822-YxO4M39r7I>