From: Xinliang David Li <davidxl@google.com>
To: Jan Hubicka <hubicka@ucw.cz>
Cc: "gcc@gcc.gnu.org" <gcc@gcc.gnu.org>,
Eugene Rozenfeld <Eugene.Rozenfeld@microsoft.com>
Subject: Re: State of AutoFDO in GCC
Date: Fri, 23 Apr 2021 10:28:06 -0700 [thread overview]
Message-ID: <CAAkRFZJObSNo3wSmhfHE0unYNKR5UDWv1D8GC0w0WkWwJo1GkA@mail.gmail.com> (raw)
In-Reply-To: <CAAkRFZJDDEHqDLwzzxNp8kmV9QhcK95ZbDCmO34zVTywoj2RYA@mail.gmail.com>
On Fri, Apr 23, 2021 at 10:27 AM Xinliang David Li <davidxl@google.com>
wrote:
>
>
> On Fri, Apr 23, 2021 at 10:16 AM Jan Hubicka <hubicka@ucw.cz> wrote:
>
>> >
>> > It uses create_llvm_prof tool which is in the same git repo. The data
>> > parsing part is shared with create_gcov, but the writer is obviously
>> > different for the two tools.
>>
>> OK and what are the main differences between llvmand gcc format?
>>
>> GCC expects GCOV format, I think while LLVM uses a newly designed binary
> format.
>
>
Sorry I missed your next reply. I forgot about the details of GCC' format.
David
>
>
>> Honza
>> >
>> > David
>> >
>> >
>> > > Honza
>> > > >
>> > > > David
>> > > >
>> > > > >
>> > > > > Thoughts?
>> > > > > Martin
>> > > > >
>> > > > > >
>> > > > > > Having the tool third-party makes keeping the whole chain
>> working
>> > > more
>> > > > > > difficult.
>> > > > > >
>> > > > > > Richard.
>> > > > > >
>> > > > > >> Thanks,
>> > > > > >>
>> > > > > >> David
>> > > > > >>
>> > > > > >> On Thu, Apr 22, 2021 at 3:29 PM Jan Hubicka <hubicka@ucw.cz>
>> wrote:
>> > > > > >>
>> > > > > >>>> On 4/22/21 9:58 PM, Eugene Rozenfeld via Gcc wrote:
>> > > > > >>>>> GCC documentation for AutoFDO points to create_gcov tool
>> that
>> > > > > converts
>> > > > > >>> perf.data file into gcov format that can be consumed by gcc
>> with
>> > > > > >>> -fauto-profile (
>> > > > > https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html,
>> > > > > >>> https://gcc.gnu.org/wiki/AutoFDO/Tutorial).
>> > > > > >>>>>
>> > > > > >>>>> I noticed that the source code for create_gcov has been
>> deleted
>> > > from
>> > > > > >>> https://github.com/google/autofdo on April 7. I asked about
>> that
>> > > > > change
>> > > > > >>> in that repo and got the following reply:
>> > > > > >>>>>
>> > > > > >>>>>
>> > > https://github.com/google/autofdo/pull/107#issuecomment-819108738
>> > > > > >>>>>
>> > > > > >>>>> "Actually we didn't use create_gcov and havn't updated
>> > > create_gcov
>> > > > > for
>> > > > > >>> years, and we also didn't have enough tests to guarantee it
>> works
>> > > (It
>> > > > > was
>> > > > > >>> gcc-4.8 when we used and verified create_gcov). If you need
>> it, it
>> > > is
>> > > > > >>> welcomed to update create_gcov and add it to the respository."
>> > > > > >>>>>
>> > > > > >>>>> Does this mean that AutoFDO is currently dead in gcc?
>> > > > > >>>>
>> > > > > >>>> Hello.
>> > > > > >>>>
>> > > > > >>>> Yes. I know that even basic test cases have been broken for
>> years
>> > > in
>> > > > > the
>> > > > > >>> GCC.
>> > > > > >>>> It's new to me that create_gcov was removed.
>> > > > > >>>>
>> > > > > >>>> I tend to send patch to GCC that will remove AutoFDO from
>> GCC.
>> > > > > >>>> I known Bin spent some time working on AutoFDO, has he came
>> up to
>> > > > > >>> something?
>> > > > > >>>
>> > > > > >>> The GCC side of auto-FDO is not that hard. We have most of
>> > > > > >>> infrastructure in place, but stopping point for me was always
>> > > > > difficulty
>> > > > > >>> to get gcov-tool working. If some maintainer steps up, I
>> think I
>> > > can
>> > > > > >>> fix GCC side.
>> > > > > >>>
>> > > > > >>> I am bit unsure how important feature it is - we have FDO that
>> > > works
>> > > > > >>> quite well for most users but I know there are some users of
>> the
>> > > LLVM
>> > > > > >>> implementation and there is potential to tie this with other
>> > > hardware
>> > > > > >>> events to asist i.e. if conversion (where one wants to know
>> how
>> > > well
>> > > > > CPU
>> > > > > >>> predicts the jump rather than just the jump probability)
>> which I
>> > > always
>> > > > > >>> found potentially interesting.
>> > > > > >>>
>> > > > > >>> Honza
>> > > > > >>>>
>> > > > > >>>> Martin
>> > > > > >>>>
>> > > > > >>>>>
>> > > > > >>>>> Thanks,
>> > > > > >>>>>
>> > > > > >>>>> Eugene
>> > > > > >>>>>
>> > > > > >>>>
>> > > > > >>>
>> > > > >
>> > > > >
>> > >
>>
>
next prev parent reply other threads:[~2021-04-23 17:28 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-22 19:58 Eugene Rozenfeld
2021-04-22 20:16 ` Martin Liška
2021-04-22 22:29 ` Jan Hubicka
2021-04-23 4:14 ` Xinliang David Li
2021-04-23 7:00 ` Richard Biener
2021-04-23 7:18 ` Martin Liška
2021-04-23 9:32 ` Richard Biener
2021-04-23 16:41 ` Xinliang David Li
2021-04-23 16:54 ` Jan Hubicka
2021-04-23 17:04 ` Xinliang David Li
2021-04-23 17:16 ` Jan Hubicka
2021-04-23 17:27 ` Xinliang David Li
2021-04-23 17:28 ` Xinliang David Li [this message]
2021-04-23 19:28 ` Jan Hubicka
2021-04-23 19:58 ` Xinliang David Li
2021-04-25 19:07 ` Jan Hubicka
2021-04-25 23:18 ` Xinliang David Li
2021-04-26 4:22 ` Wei Mi
2021-04-26 15:11 ` Andi Kleen
2021-04-26 16:57 ` Xinliang David Li
2021-04-26 18:00 ` Andi Kleen
2021-04-26 18:05 ` Xinliang David Li
2021-04-26 18:40 ` Hongtao Yu
2021-04-26 19:13 ` Andi Kleen
2021-04-29 5:40 ` Andi Kleen
2021-04-29 14:45 ` 172060045
2021-04-30 21:43 ` Andi Kleen
2021-05-08 11:25 ` 172060045
2021-05-09 16:28 ` Andi Kleen
2021-05-09 17:01 ` Jan Hubicka
2021-05-10 15:36 ` Andi Kleen
2021-05-10 16:55 ` Joseph Myers
2021-05-10 17:21 ` Andi Kleen
2022-07-26 20:12 ` Eugene Rozenfeld
2022-07-26 22:37 ` David Edelsohn
2022-07-27 7:26 ` Jan Hubicka
2022-07-27 18:30 ` [EXTERNAL] " Eugene Rozenfeld
2022-07-27 18:24 ` Eugene Rozenfeld
2022-07-27 1:31 ` Xionghu Luo
2022-07-27 1:41 ` Xionghu Luo
2022-07-27 18:38 ` [EXTERNAL] " Eugene Rozenfeld
2021-05-10 23:46 ` Wei Mi
2021-05-22 1:28 ` [EXTERNAL] " Eugene Rozenfeld
2021-05-22 16:36 ` Wei Mi
2021-05-25 1:39 ` Eugene Rozenfeld
2021-05-25 3:11 ` Wei Mi
2021-05-25 3:33 ` Eugene Rozenfeld
2021-05-25 3:54 ` Wei Mi
2021-05-25 7:01 ` Eugene Rozenfeld
2021-05-25 16:16 ` Wei Mi
2021-05-25 20:49 ` Eugene Rozenfeld
2021-05-26 3:06 ` Wei Mi
2021-05-26 23:39 ` Eugene Rozenfeld
2021-05-27 2:51 ` Wei Mi
2021-06-12 1:14 ` Eugene Rozenfeld
2021-06-14 17:00 ` Wei Mi
2021-04-23 17:20 ` Jan Hubicka
2021-04-23 16:36 ` Xinliang David Li
2021-04-30 18:48 ` [EXTERNAL] " Eugene Rozenfeld
2021-04-30 21:45 ` Andi Kleen
2021-06-24 21:45 ` Eugene Rozenfeld
2021-04-23 1:46 ` Bin.Cheng
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAAkRFZJObSNo3wSmhfHE0unYNKR5UDWv1D8GC0w0WkWwJo1GkA@mail.gmail.com \
--to=davidxl@google.com \
--cc=Eugene.Rozenfeld@microsoft.com \
--cc=gcc@gcc.gnu.org \
--cc=hubicka@ucw.cz \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).