From: Nick Desaulniers <nick.desaulniers@gmail.com>
To: ndesaulniers@google.com
Cc: akpm@linux-foundation.org, clang-built-linux@googlegroups.com,
corbet@lwn.net, linux-doc@vger.kernel.org,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
masahiroy@kernel.org, morbo@google.com, natechancellor@gmail.com,
samitolvanen@google.com, torvalds@linux-foundation.org
Subject: Re: [PATCH v4] pgo: add clang's Profile Guided Optimization infrastructure
Date: Fri, 15 Jan 2021 16:13:24 -0800 [thread overview]
Message-ID: <20210116001324.2865-1-nick.desaulniers@gmail.com> (raw)
In-Reply-To: <CAKwvOd=rEngs-8DR6pagynYc5-=a06brTOOx5TT1TC+v7-3m2Q@mail.gmail.com>
> On Wed, Jan 13, 2021 at 8:07 PM Nick Desaulniers
> <ndesaulniers@google.com> wrote:
> >
> > On Wed, Jan 13, 2021 at 12:55 PM Nathan Chancellor
> > <natechancellor@gmail.com> wrote:
> > >
> > > However, I see an issue with actually using the data:
> > >
> > > $ sudo -s
> > > # mount -t debugfs none /sys/kernel/debug
> > > # cp -a /sys/kernel/debug/pgo/profraw vmlinux.profraw
> > > # chown nathan:nathan vmlinux.profraw
> > > # exit
> > > $ tc-build/build/llvm/stage1/bin/llvm-profdata merge --output=vmlinux.profdata vmlinux.profraw
> > > warning: vmlinux.profraw: Invalid instrumentation profile data (bad magic)
> > > error: No profiles could be merged.
> > >
> > > Am I holding it wrong? :) Note, this is virtualized, I do not have any
> > > "real" x86 hardware that I can afford to test on right now.
> >
> > Same.
> >
> > I think the magic calculation in this patch may differ from upstream
> > llvm: https://github.com/llvm/llvm-project/blob/49142991a685bd427d7e877c29c77371dfb7634c/llvm/include/llvm/ProfileData/SampleProf.h#L96-L101
>
> Err...it looks like it was the padding calculation. With that fixed
> up, we can query the profile data to get insights on the most heavily
> called functions. Here's what my top 20 are (reset, then watch 10
> minutes worth of cat videos on youtube while running `find /` and
> sleeping at my desk). Anything curious stand out to anyone?
Hello world from my personal laptop whose kernel was rebuilt with
profiling data! Wow, I can run `find /` and watch cat videos on youtube
so fast! Users will love this! /s
Checking the sections sizes of .text.hot. and .text.unlikely. looks
good!
>
> $ llvm-profdata show -topn=20 /tmp/vmlinux.profraw
> Instrumentation level: IR entry_first = 0
> Total functions: 48970
> Maximum function count: 62070879
> Maximum internal block count: 83221158
> Top 20 functions with the largest internal block counts:
> drivers/tty/n_tty.c:n_tty_write, max count = 83221158
> rcu_read_unlock_strict, max count = 62070879
> _cond_resched, max count = 25486882
> rcu_all_qs, max count = 25451477
> drivers/cpuidle/poll_state.c:poll_idle, max count = 23618576
> _raw_spin_unlock_irqrestore, max count = 18874121
> drivers/cpuidle/governors/menu.c:menu_select, max count = 18721624
> _raw_spin_lock_irqsave, max count = 18509161
> memchr, max count = 15525452
> _raw_spin_lock, max count = 15484254
> __mod_memcg_state, max count = 14604619
> __mod_memcg_lruvec_state, max count = 14602783
> fs/ext4/hash.c:str2hashbuf_signed, max count = 14098424
> __mod_lruvec_state, max count = 12527154
> __mod_node_page_state, max count = 12525172
> native_sched_clock, max count = 8904692
> sched_clock_cpu, max count = 8895832
> sched_clock, max count = 8894627
> kernel/entry/common.c:exit_to_user_mode_prepare, max count = 8289031
> fpregs_assert_state_consistent, max count = 8287198
>
> --
> Thanks,
> ~Nick Desaulniers
>
next prev parent reply other threads:[~2021-01-16 0:14 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 [this message]
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
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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