From: "David Wang" <00107082@163.com>
To: musl@lists.openwall.com
Cc: "Markus Wichmann" <nullplan@gmx.net>
Subject: [musl] Re:Re: [musl] Re:Re: [musl] Re:Re: [musl] qsort
Date: Fri, 10 Feb 2023 21:45:12 +0800 (CST) [thread overview]
Message-ID: <23b37232.4d4c.1863b92aa13.Coremail.00107082@163.com> (raw)
In-Reply-To: <20230210131044.GZ4163@brightrain.aerifal.cx>
At 2023-02-10 21:10:45, "Rich Felker" <dalias@libc.org> wrote:
>On Fri, Feb 10, 2023 at 06:00:27PM +0800, David Wang wrote:
>What tool was used for this? gprof or anything else invasive is not
>meaningful; for tiny functions, the entire time measured will be the
>profiling overhead. perf(1) is the only way I know to get meaningful
>numbers.
>
>In particular, it makes no sense that significant time was spent in
>wrapper_cmp, which looks like (i386):
>
> 0: ff 64 24 0c jmp *0xc(%esp)
>
>or (x86_64):
>
> 0: ff e2 jmpq *%rdx
>
>or (arm):
>
> 0: 4710 bx r2
>
>but I can imagine it being (relatively) gigantic with a call out to
>profiling code.
>
>Rich
I have myself implemented a profiling tool, using perf_event_open to start profiling and mmap to collect callchains, the source code is here https://github.com/zq-david-wang/linux-tools/blob/main/perf/profiler/profiler.cpp
(Still buggy, there is always strange callchain which I could not figure out...and I am still working on it...)
Also, I did not use any optimization when compile the code, which could make a difference, I will take time to give it a try .
About wrapper_cmp, in my last profiling, there are total 931387 samples collected, 257403 samples contain callchain ->wrapper_cmp, among those 257403 samples, 167410 samples contain callchain ->wrapper_cmp->mycmp,
that is why I think there is extra overhead about wrapper_cmp. Maybe compiler optimization would change the result, and I will make further checks.
David
next prev parent reply other threads:[~2023-02-10 13:45 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-20 1:49 Guy
2023-01-20 12:55 ` alice
2023-01-30 10:04 ` [musl] " David Wang
2023-02-01 18:01 ` Markus Wichmann
2023-02-02 2:12 ` [musl] " David Wang
2023-02-03 5:22 ` [musl] " David Wang
2023-02-03 8:03 ` Alexander Monakov
2023-02-03 9:01 ` [musl] " David Wang
2023-02-09 19:03 ` Rich Felker
2023-02-09 19:20 ` Alexander Monakov
2023-02-09 19:52 ` Rich Felker
2023-02-09 20:18 ` Rich Felker
2023-02-09 20:27 ` Pierpaolo Bernardi
2023-02-10 4:10 ` Markus Wichmann
2023-02-10 10:00 ` [musl] " David Wang
2023-02-10 13:10 ` Rich Felker
2023-02-10 13:45 ` David Wang [this message]
2023-02-10 14:19 ` [musl] " Rich Felker
2023-02-11 5:12 ` [musl] " David Wang
2023-02-11 5:44 ` alice
2023-02-11 8:39 ` Joakim Sindholt
2023-02-11 9:06 ` alice
2023-02-11 9:31 ` [musl] " David Wang
2023-02-11 13:35 ` Rich Felker
2023-02-11 17:18 ` David Wang
2023-02-16 15:15 ` David Wang
2023-02-16 16:07 ` Rich Felker
2023-02-17 1:35 ` [musl] " David Wang
2023-02-17 13:17 ` Alexander Monakov
2023-02-17 15:07 ` Rich Felker
2023-02-11 9:22 ` [musl] " Markus Wichmann
2023-02-11 9:36 ` [musl] " David Wang
2023-02-11 9:51 ` David Wang
2023-01-20 13:32 ` [musl] qsort Valery Ushakov
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=23b37232.4d4c.1863b92aa13.Coremail.00107082@163.com \
--to=00107082@163.com \
--cc=musl@lists.openwall.com \
--cc=nullplan@gmx.net \
/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.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/musl/
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 NNTP newsgroup(s).