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From: Bill Wendling <morbo@google.com>
To: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Linux Doc Mailing List <linux-doc@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	Clang-Built-Linux ML <clang-built-linux@googlegroups.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Nathan Chancellor <natechancellor@gmail.com>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Sami Tolvanen <samitolvanen@google.com>,
	Fangrui Song <maskray@google.com>
Subject: Re: [PATCH v5] pgo: add clang's Profile Guided Optimization infrastructure
Date: Sun, 17 Jan 2021 18:32:25 -0800	[thread overview]
Message-ID: <CAGG=3QWmOA+yM2GJF+cHUb7wUq6yiBpHasa-ry9OhAdvciDm6Q@mail.gmail.com> (raw)
In-Reply-To: <CA+icZUUuzA5JEXyVzKbVX+T3xeOdRAU6-mntbo+VwwTxqmN7LA@mail.gmail.com>

On Sun, Jan 17, 2021 at 4:27 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>
> [ big snip ]

[More snippage.]

> [ CC Fangrui ]
>
> With the attached...
>
>    [PATCH v3] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for
> undefined symbols
>
> ...I was finally able to boot into a rebuild PGO-optimized Linux-kernel.
> For details see ClangBuiltLinux issue #1250 "Unknown symbol
> _GLOBAL_OFFSET_TABLE_ loading kernel modules".
>
Thanks for confirming that this works with the above patch.

> @ Bill Nick Sami Nathan
>
> 1, Can you say something of the impact passing "LLVM_IAS=1" to make?

The integrated assembler and this option are more-or-less orthogonal
to each other. One can still use the GNU assembler with PGO. If you're
having an issue, it may be related to ClangBuiltLinux issue #1250.

> 2. Can you please try Nick's DWARF v5 support patchset v5 and
> CONFIG_DEBUG_INFO_DWARF5=y (see attachments)?
>
I know Nick did several tests with PGO. He may have looked into it
already, but we can check.

> I would like to know what the impact of the Clang's Integrated
> Assembler and DWARF v5 are.
>
> I dropped both means...
>
> 1. Do not pass "LLVM_IAS=1" to make.
> 2. Use default DWARF v2 (with Nick's patchset: CONFIG_DEBUG_INFO_DWARF2=y).
>
> ...for a successfull build and boot on bare metal.
>

[Next message]

> On each rebuild I need to pass to make ...?
>
>   LLVM=1 -fprofile-use=vmlinux.profdata
>
Yes.

> Did you try together with passing LLVM_IAS=1 to make?

One of my tests was with the integrated assembler enabled. Are you
finding issues with it?

The problem with using top-of-tree clang is that it's not necessarily
stable. You could try using the clang 11.x release (changing the
"CLANG_VERSION >= 120000" in kernel/pgo/Kconfig/ to "CLANG_VERSION >=
110000").

-bw

  reply	other threads:[~2021-01-18  2:33 UTC|newest]

Thread overview: 122+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-11  8:18 [PATCH] pgo: add clang's Profile Guided Optimization infrastructure Bill Wendling
2021-01-11  8:39 ` Sedat Dilek
2021-01-11  8:42   ` Sedat Dilek
2021-01-11  9:17   ` Bill Wendling
2021-01-11  9:57     ` Sedat Dilek
2021-01-11 18:28       ` Nathan Chancellor
2021-01-11 20:12 ` Fangrui Song
2021-01-11 20:23   ` Bill Wendling
2021-01-11 20:31     ` Fangrui Song
2021-01-12  0:37       ` Bill Wendling
2021-01-12  0:44         ` Fāng-ruì Sòng
2021-01-11 21:04 ` Nathan Chancellor
2021-01-11 21:17   ` Nick Desaulniers
2021-01-11 21:32     ` Bill Wendling
2021-01-12  5:14 ` [PATCH v2] " Bill Wendling
2021-01-12  5:17   ` Sedat Dilek
2021-01-12  5:31   ` [PATCH v3] " Bill Wendling
2021-01-12  9:10     ` kernel test robot
2021-01-12 17:22       ` Nathan Chancellor
2021-01-13  6:19     ` [PATCH v4] " Bill Wendling
2021-01-13 20:55       ` Nathan Chancellor
2021-01-13 21:59         ` Bill Wendling
2021-01-14  4:07         ` Nick Desaulniers
2021-01-16  0:01           ` Nick Desaulniers
2021-01-16  0:13             ` Nick Desaulniers
2021-01-16  4:30               ` Sedat Dilek
2021-01-16  5:07               ` Sedat Dilek
2021-01-16  5:18                 ` Sedat Dilek
2021-01-18  0:57               ` Sedat Dilek
2021-01-13 23:01       ` Nick Desaulniers
2021-01-16  9:43       ` [PATCH v5] " Bill Wendling
2021-01-16 17:38         ` Sedat Dilek
2021-01-16 18:36           ` Sedat Dilek
2021-01-16 20:23           ` Bill Wendling
2021-01-17 10:44             ` Sedat Dilek
2021-01-17 10:53               ` Sedat Dilek
2021-01-17 11:23                 ` Sedat Dilek
2021-01-17 11:42                   ` Sedat Dilek
2021-01-17 11:58                     ` Sedat Dilek
2021-01-17 12:05                       ` Sedat Dilek
2021-01-17 17:42                         ` Sedat Dilek
2021-01-17 20:34                           ` Bill Wendling
2021-01-17 23:33                             ` Sedat Dilek
2021-01-18  0:26                               ` Sedat Dilek
2021-01-18  2:32                                 ` Bill Wendling [this message]
2021-01-18 12:39                                   ` Sedat Dilek
2021-01-18 17:26                                     ` Sedat Dilek
2021-01-18 21:56                                       ` Bill Wendling
2021-01-18 23:29                                         ` Sedat Dilek
2021-01-21  2:03                                         ` Sedat Dilek
2021-01-21 22:44                                           ` Sedat Dilek
2021-01-22  1:42                                           ` Nick Desaulniers
2021-01-22  1:49                                             ` Sedat Dilek
2021-01-22  1:52                                               ` Nick Desaulniers
2021-01-22  1:54                                                 ` Sedat Dilek
2021-01-20  1:02         ` Nick Desaulniers
2021-01-21  0:51         ` Nick Desaulniers
2021-01-21  8:24           ` Bill Wendling
2021-01-21  8:24         ` [PATCH v6] " Bill Wendling
2021-01-21 10:34           ` Sedat Dilek
2021-01-22  1:44             ` Nick Desaulniers
2021-01-22  1:51               ` Sedat Dilek
2021-01-22  0:14           ` Sedat Dilek
2021-01-22  0:58             ` Sedat Dilek
2021-01-22  1:29           ` Nick Desaulniers
2021-01-22 10:11           ` [PATCH v7] " Bill Wendling
2021-01-22 11:31             ` Sedat Dilek
2021-01-22 18:41             ` Nick Desaulniers
2021-01-28 20:46               ` Sedat Dilek
2021-01-28 21:12                 ` Nick Desaulniers
2021-01-28 21:19                   ` Sedat Dilek
2021-01-28 21:24                     ` Nick Desaulniers
2021-01-28 21:39                       ` Sedat Dilek
2021-01-29  7:43               ` Sedat Dilek
2021-01-29 21:48                 ` Nick Desaulniers
2021-02-10 23:25             ` Bill Wendling
2021-02-22 21:52               ` Bill Wendling
2021-02-26 22:20             ` [PATCH v8] " Bill Wendling
2021-02-26 22:55               ` Bill Wendling
2021-02-28 18:52               ` Fangrui Song
2021-02-28 21:50                 ` Fangrui Song
2021-01-12 17:37   ` [PATCH v2] " Nick Desaulniers
2021-01-12 17:45     ` Fāng-ruì Sòng
2021-01-21  2:21 ` [PATCH] " Sedat Dilek
2021-01-22  1:34   ` Nick Desaulniers
2021-01-22  1:43     ` Sedat Dilek
2021-04-07 21:17 ` [PATCH v9] " Bill Wendling
2021-04-07 21:22   ` Kees Cook
2021-04-07 21:44     ` Fāng-ruì Sòng
2021-04-07 21:47   ` Nathan Chancellor
2021-04-07 21:58     ` Bill Wendling
2021-05-19 21:37   ` Kees Cook
2021-05-22 23:51     ` Bill Wendling
2021-05-31 21:12     ` Nathan Chancellor
2021-06-01 17:31       ` Nick Desaulniers
2021-06-12 16:59   ` Peter Zijlstra
2021-06-12 17:25     ` Bill Wendling
2021-06-12 18:15       ` Peter Zijlstra
2021-06-12 19:10         ` Bill Wendling
2021-06-12 19:28           ` Bill Wendling
2021-06-12 20:25           ` Peter Zijlstra
2021-06-12 20:56             ` Bill Wendling
2021-06-12 22:47               ` Bill Wendling
2021-06-13 18:07                 ` Bill Wendling
2021-06-14  9:43                   ` Peter Zijlstra
2021-06-14 10:18                     ` Peter Zijlstra
2021-06-14  7:51               ` Peter Zijlstra
2021-06-14  9:01               ` Peter Zijlstra
2021-06-14  9:39                 ` Bill Wendling
2021-06-14 10:44                   ` Peter Zijlstra
2021-06-14 11:41                     ` Bill Wendling
2021-06-14 11:43                     ` Bill Wendling
2021-06-14 14:16                     ` Marco Elver
2021-06-14 15:26                       ` Kees Cook
2021-06-14 15:35                         ` Peter Zijlstra
2021-06-14 16:22                           ` Kees Cook
2021-06-14 18:07                             ` Nick Desaulniers
2021-06-14 20:49                               ` Nick Desaulniers
2021-06-14 15:46                         ` Peter Zijlstra
2021-06-14 16:03                           ` Nick Desaulniers
2021-06-12 20:20         ` Fangrui Song
2021-06-12 20:31           ` Peter Zijlstra

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