From: Sedat Dilek <sedat.dilek@gmail.com>
To: Nick Desaulniers <nick.desaulniers@gmail.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
akpm@linux-foundation.org,
Clang-Built-Linux ML <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, Bill Wendling <morbo@google.com>,
Nathan Chancellor <natechancellor@gmail.com>,
Sami Tolvanen <samitolvanen@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH v4] pgo: add clang's Profile Guided Optimization infrastructure
Date: Mon, 18 Jan 2021 01:57:32 +0100 [thread overview]
Message-ID: <CA+icZUXsK8nfRQGatBoMAsjxhA=VEgZDsPsEg8o7i7yP+ko2Lg@mail.gmail.com> (raw)
In-Reply-To: <20210116001324.2865-1-nick.desaulniers@gmail.com>
On Sat, Jan 16, 2021 at 1:13 AM Nick Desaulniers
<nick.desaulniers@gmail.com> wrote:
>
> > 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!
>
On each rebuild I need to pass to make ...?
LLVM=1 -fprofile-use=vmlinux.profdata
Did you try together with passing LLVM_IAS=1 to make?
- Sedat -
> >
> > $ 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
> >
>
> --
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next prev parent reply other threads:[~2021-01-18 1:00 UTC|newest]
Thread overview: 116+ 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
[not found] ` <202101121755.pyYoRozB-lkp@intel.com>
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 [this message]
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
[not found] ` <CA+icZUXmn15w=kSq2CZzQD5JggJw_9AEam=Sz13M0KpJ68MWZg@mail.gmail.com>
2021-01-17 17:42 ` Sedat Dilek
2021-01-17 20:34 ` Bill Wendling
[not found] ` <CA+icZUU1HihUFaEHzF69+01+Picg8aq6HAqHupxiRqyDGJ=Mpw@mail.gmail.com>
[not found] ` <CA+icZUUuzA5JEXyVzKbVX+T3xeOdRAU6-mntbo+VwwTxqmN7LA@mail.gmail.com>
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
2021-01-20 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
[not found] ` <CA+icZUU=XfwqMcXYonQKcD4QgqTBW-mA+d_84b7cU2R3HYPOSQ@mail.gmail.com>
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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