From: Linus Torvalds <torvalds@linux-foundation.org>
To: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: Ingo Molnar <mingo@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [GIT PULL] perf fixes
Date: Fri, 22 Jun 2012 11:52:43 -0700 [thread overview]
Message-ID: <CA+55aFzpNtLSQvcOOut--2UkkMyqSb9e0_VO3JAxvZRTv7YT1g@mail.gmail.com> (raw)
In-Reply-To: <20120622183827.GA8014@virgo.local>
On Fri, Jun 22, 2012 at 11:38 AM, Hagen Paul Pfeifer <hagen@jauu.net> wrote:
>>
>>Because that mcount thing is expensive as hell, if people haven't
>>noticed (and I'm not talking about just the call instruction that I
>>think we can stub out - it changes code generation in other ways too).
>>And it looks like distros enable it by default, which annoys my
>>performance-optimizing soul deeply.
>
> Isn't it stubed out already? Already replaced by nops at boot time by
> ftrace_code_disable() and friends!? But yes, there may be spots where the
> additional mcount() call avoid optimization.
So even stubbed out, it's quite noticeable. The call causes the
function prologue to change quite a bit.
That's actually especially true with newer versions of gcc that
*finally* seem to have done the "don't always generate the full
prologue if some case doesn't need it" optimization. So functions that
have early-out conditions (quite common) will exit before even having
done the prologue, and without doing the whole frame pointer setup
etc.
Except if mcount generation is on. Then gcc will always do the
prologue and frame pointer setup before doing the mcount, because
mcount wants it.
So it really isn't just the extra call instruction.
I may be more sensitive to this than most, because I look at profiles
and the function prologue just looks very ugly with the call mcount
thing. Ugh.
Linus
next prev parent reply other threads:[~2012-06-22 18:53 UTC|newest]
Thread overview: 376+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-22 13:36 [GIT PULL] perf fixes Ingo Molnar
2012-06-22 18:07 ` Linus Torvalds
2012-06-22 18:38 ` Hagen Paul Pfeifer
2012-06-22 18:52 ` Linus Torvalds [this message]
2012-06-22 19:06 ` Hagen Paul Pfeifer
2012-06-22 19:54 ` Steven Rostedt
[not found] ` <86448d73-2e19-416f-8104-ce72aa5d76eb@email.android.com>
2012-06-22 23:18 ` Steven Rostedt
2012-06-23 0:51 ` Arjan van de Ven
2012-06-23 1:57 ` Steven Rostedt
2012-06-23 18:25 ` H. Peter Anvin
2012-06-22 18:50 ` Steven Rostedt
-- strict thread matches above, loose matches on Subject: below --
2023-01-06 11:57 Ingo Molnar
2023-01-06 21:19 ` pr-tracker-bot
2022-10-02 10:56 Ingo Molnar
2022-10-02 16:47 ` Linus Torvalds
2022-10-03 10:55 ` Ingo Molnar
2022-10-02 17:20 ` pr-tracker-bot
2022-08-28 14:35 Ingo Molnar
2022-08-28 18:18 ` pr-tracker-bot
2022-08-06 19:10 Ingo Molnar
2022-08-07 0:50 ` pr-tracker-bot
2021-07-11 13:26 Ingo Molnar
2021-07-11 18:22 ` pr-tracker-bot
2021-06-12 12:48 Ingo Molnar
2021-06-12 19:09 ` pr-tracker-bot
2021-03-21 10:56 Ingo Molnar
2021-03-21 18:45 ` pr-tracker-bot
2020-08-15 11:21 Ingo Molnar
2020-08-16 1:55 ` pr-tracker-bot
2020-04-25 9:19 Ingo Molnar
2020-04-25 19:30 ` pr-tracker-bot
2020-03-24 9:19 Ingo Molnar
2020-03-24 17:15 ` pr-tracker-bot
2020-03-02 7:23 Ingo Molnar
2020-03-03 23:35 ` pr-tracker-bot
2020-02-15 8:53 Ingo Molnar
2020-02-15 21:25 ` pr-tracker-bot
2020-01-18 17:58 Ingo Molnar
2020-01-18 21:05 ` pr-tracker-bot
2019-12-21 16:16 Ingo Molnar
2019-12-21 18:55 ` pr-tracker-bot
2019-12-17 11:34 Ingo Molnar
2019-12-17 19:06 ` Linus Torvalds
2019-12-18 6:58 ` Ingo Molnar
2019-12-17 19:20 ` pr-tracker-bot
2019-12-01 22:15 Ingo Molnar
2019-12-02 4:40 ` pr-tracker-bot
2019-11-16 21:33 Ingo Molnar
2019-11-17 0:35 ` pr-tracker-bot
2019-11-01 17:48 Ingo Molnar
2019-11-01 18:48 ` Linus Torvalds
2019-11-01 20:30 ` Ingo Molnar
2019-11-01 21:01 ` Ingo Molnar
2019-11-01 22:15 ` Linus Torvalds
2019-11-01 19:10 ` pr-tracker-bot
2019-10-12 13:31 Ingo Molnar
2019-10-12 22:35 ` pr-tracker-bot
2019-07-14 12:01 Ingo Molnar
2019-07-14 18:45 ` pr-tracker-bot
2019-06-29 8:54 Ingo Molnar
2019-06-29 11:45 ` pr-tracker-bot
2019-06-02 17:39 Ingo Molnar
2019-06-02 18:15 ` pr-tracker-bot
2019-05-16 16:05 Ingo Molnar
2019-05-16 18:20 ` pr-tracker-bot
2019-05-05 12:47 Ingo Molnar
2019-05-05 22:10 ` pr-tracker-bot
2019-04-20 7:43 Ingo Molnar
2019-04-20 19:25 ` pr-tracker-bot
2019-04-12 13:06 Ingo Molnar
2019-04-13 4:05 ` pr-tracker-bot
2019-02-17 10:10 Ingo Molnar
2019-02-17 16:50 ` pr-tracker-bot
2019-02-10 9:01 Ingo Molnar
2019-02-10 18:30 ` pr-tracker-bot
2019-01-11 7:44 Ingo Molnar
2019-01-11 18:00 ` pr-tracker-bot
2018-11-30 6:25 Ingo Molnar
2018-11-30 21:00 ` pr-tracker-bot
2018-11-17 10:55 Ingo Molnar
2018-11-18 20:05 ` pr-tracker-bot
2018-10-20 8:10 Ingo Molnar
2018-10-20 13:28 ` Greg Kroah-Hartman
2018-10-11 9:12 Ingo Molnar
2018-10-11 12:32 ` Greg Kroah-Hartman
2018-10-11 8:59 Ingo Molnar
2018-10-05 9:42 Ingo Molnar
2018-10-05 9:55 ` Ingo Molnar
2018-10-05 23:30 ` Greg Kroah-Hartman
2018-09-15 13:11 Ingo Molnar
2018-07-30 17:53 Ingo Molnar
2018-07-13 19:59 Ingo Molnar
2018-06-30 8:44 Ingo Molnar
2018-06-04 9:04 Ingo Molnar
2018-03-31 10:40 Ingo Molnar
2018-03-25 8:53 Ingo Molnar
2018-02-06 21:29 Ingo Molnar
2017-12-06 22:17 Ingo Molnar
2017-11-26 12:40 Ingo Molnar
2017-11-05 14:40 Ingo Molnar
2017-11-09 8:13 ` Markus Trippelsdorf
2017-10-14 16:04 Ingo Molnar
2017-09-13 18:00 Ingo Molnar
2017-09-12 15:32 Ingo Molnar
2017-07-21 10:15 Ingo Molnar
2017-06-10 8:39 Ingo Molnar
2017-05-12 7:31 Ingo Molnar
2017-03-07 20:30 Ingo Molnar
2017-02-28 8:01 Ingo Molnar
2017-02-11 18:12 Ingo Molnar
2017-02-02 21:01 Ingo Molnar
2017-01-18 9:27 Ingo Molnar
2017-01-15 9:59 Ingo Molnar
2016-12-23 22:50 Ingo Molnar
2016-12-07 18:45 Ingo Molnar
2016-11-23 9:00 Ingo Molnar
2016-11-14 7:56 Ingo Molnar
2016-10-28 19:41 Ingo Molnar
2016-10-18 11:07 Ingo Molnar
2016-09-13 18:14 Ingo Molnar
2016-08-18 20:38 Ingo Molnar
2016-08-12 19:35 Ingo Molnar
2016-07-26 14:13 Ingo Molnar
2016-07-08 13:42 Ingo Molnar
2016-06-10 12:50 Ingo Molnar
2016-05-13 18:51 Ingo Molnar
2016-05-06 11:26 Ingo Molnar
2016-04-28 17:56 Ingo Molnar
2016-04-03 11:00 Ingo Molnar
2016-02-20 11:14 Ingo Molnar
2016-01-14 10:03 Ingo Molnar
2016-01-08 12:46 Ingo Molnar
2015-12-08 4:22 Ingo Molnar
2015-09-17 8:02 Ingo Molnar
2015-09-02 18:11 Ingo Molnar
2015-08-22 12:19 Ingo Molnar
2015-08-14 7:12 Ingo Molnar
2015-07-18 2:53 Ingo Molnar
2015-07-06 15:29 Ingo Molnar
2015-06-13 14:29 Ingo Molnar
2015-06-05 8:37 Ingo Molnar
2015-05-15 7:17 Ingo Molnar
2015-05-06 12:52 Ingo Molnar
2015-04-03 13:11 Ingo Molnar
2015-03-17 16:48 Ingo Molnar
2015-03-01 17:00 Ingo Molnar
2015-02-20 13:40 Ingo Molnar
2015-01-30 18:44 Ingo Molnar
2015-01-17 14:15 Ingo Molnar
2015-01-11 8:42 Ingo Molnar
2014-11-20 7:46 Ingo Molnar
2014-10-31 11:13 Ingo Molnar
2014-11-03 9:02 ` Paul Bolle
2014-11-03 10:04 ` Peter Zijlstra
2014-09-19 10:46 Ingo Molnar
2014-08-24 20:25 Ingo Molnar
2014-07-16 11:11 Ingo Molnar
2014-06-18 16:39 Ingo Molnar
2014-05-22 8:04 Ingo Molnar
2014-05-01 6:34 Ingo Molnar
2014-04-20 8:02 Ingo Molnar
2014-04-19 10:41 Ingo Molnar
2014-04-16 13:04 Ingo Molnar
2014-03-22 9:06 Ingo Molnar
2014-03-16 16:34 Ingo Molnar
2014-03-02 8:51 Ingo Molnar
2014-02-22 19:16 Ingo Molnar
2014-02-09 8:01 Ingo Molnar
2014-01-25 7:30 Ingo Molnar
2014-01-19 12:08 Ingo Molnar
2013-12-19 16:52 Ingo Molnar
2013-12-02 14:39 Ingo Molnar
2013-11-15 19:46 Ingo Molnar
2013-11-01 9:56 Ingo Molnar
2013-10-29 10:04 Ingo Molnar
2013-10-26 12:24 Ingo Molnar
2013-10-28 8:28 ` Markus Trippelsdorf
2013-10-28 9:02 ` ------------------------------ Markus Trippelsdorf
2013-10-28 9:34 ` Markus Trippelsdorf
2013-10-28 12:34 ` Arnaldo Carvalho de Melo
2013-10-28 12:42 ` Arnaldo Carvalho de Melo
2013-10-28 12:59 ` Markus Trippelsdorf
2013-10-29 9:50 ` Stephane Eranian
2013-10-29 10:06 ` Ingo Molnar
2013-10-29 12:47 ` Arnaldo Carvalho de Melo
2013-10-08 12:12 Ingo Molnar
2013-09-28 18:03 Ingo Molnar
2013-09-29 11:47 ` Markus Trippelsdorf
2013-09-29 21:33 ` Andi Kleen
2013-09-29 22:47 ` Markus Trippelsdorf
2013-09-30 6:27 ` Ingo Molnar
2013-09-30 18:54 ` Andi Kleen
2013-10-01 8:42 ` Ingo Molnar
2013-09-25 18:00 Ingo Molnar
2013-09-18 16:06 Ingo Molnar
2013-09-12 13:38 Ingo Molnar
2013-09-12 18:03 ` Linus Torvalds
2013-09-12 18:10 ` Linus Torvalds
2013-09-12 18:43 ` Arnaldo Carvalho de Melo
2013-09-12 19:12 ` Arnaldo Carvalho de Melo
2013-09-12 19:13 ` Linus Torvalds
2013-09-12 19:55 ` Ingo Molnar
2013-09-12 19:58 ` David Ahern
2013-09-12 20:02 ` Arnaldo Carvalho de Melo
2013-09-12 20:31 ` Ingo Molnar
2013-09-12 20:43 ` Ingo Molnar
2013-09-12 20:18 ` Ingo Molnar
2013-09-12 20:38 ` Arnaldo Carvalho de Melo
2013-09-12 20:46 ` Ingo Molnar
2013-09-12 21:09 ` David Ahern
2013-09-12 21:18 ` Ingo Molnar
2013-09-12 22:10 ` David Ahern
2013-09-13 5:09 ` Ingo Molnar
2013-09-13 9:32 ` Jean Pihet
2013-09-13 9:45 ` Ingo Molnar
2013-09-13 17:15 ` Jean Pihet
2013-09-12 18:51 ` Linus Torvalds
2013-09-12 20:33 ` Ingo Molnar
2013-09-12 20:38 ` Linus Torvalds
2013-09-12 20:49 ` Ingo Molnar
2013-09-12 20:52 ` Linus Torvalds
2013-09-12 21:01 ` Ingo Molnar
2013-09-12 20:10 ` Ingo Molnar
2013-08-13 16:51 Ingo Molnar
2013-07-10 8:52 Ingo Molnar
2013-06-26 8:52 Ingo Molnar
2013-06-20 8:58 Ingo Molnar
2013-05-05 10:10 Ingo Molnar
2013-04-21 8:16 Ingo Molnar
2013-04-14 15:20 Ingo Molnar
2013-03-21 9:56 Ingo Molnar
2013-03-11 14:28 Ingo Molnar
2013-02-26 7:02 Ingo Molnar
2013-03-14 20:32 ` Linus Torvalds
2013-03-14 21:06 ` Linus Torvalds
2013-03-14 22:09 ` Stephane Eranian
2013-03-14 22:17 ` Linus Torvalds
2013-03-14 22:19 ` Stephane Eranian
2013-03-14 22:42 ` Stephane Eranian
2013-03-14 22:53 ` Stephane Eranian
2013-03-14 23:11 ` Stephane Eranian
2013-03-15 0:24 ` Stephane Eranian
2013-03-15 1:06 ` Linus Torvalds
2013-03-15 8:01 ` Stephane Eranian
2013-03-15 10:50 ` Stephane Eranian
2013-02-04 18:20 Ingo Molnar
2012-12-01 11:11 Ingo Molnar
2012-10-26 14:44 Ingo Molnar
2012-10-23 11:02 Ingo Molnar
2012-10-20 0:56 Ingo Molnar
2012-09-21 19:08 Ingo Molnar
2012-09-13 14:39 Ingo Molnar
2012-08-23 10:59 Ingo Molnar
2012-08-20 9:08 Ingo Molnar
2012-08-21 7:59 ` Ingo Molnar
2012-08-05 17:43 Ingo Molnar
2012-08-03 16:40 Ingo Molnar
2012-07-14 7:51 Ingo Molnar
2012-06-15 18:48 Ingo Molnar
2012-06-08 9:20 Ingo Molnar
2012-05-30 15:39 Ingo Molnar
2012-05-17 8:19 Ingo Molnar
2012-04-27 6:32 Ingo Molnar
2012-04-16 17:48 Ingo Molnar
2012-04-14 10:54 Ingo Molnar
2012-04-03 22:40 Ingo Molnar
2012-03-13 16:56 Ingo Molnar
2012-03-05 9:27 Ingo Molnar
2012-03-02 10:47 Ingo Molnar
2012-02-10 12:45 Ingo Molnar
2012-02-02 10:00 Ingo Molnar
2012-01-26 18:11 Ingo Molnar
2011-12-29 21:02 Ingo Molnar
2011-12-09 6:16 Ingo Molnar
2011-12-05 19:13 Ingo Molnar
2011-11-07 18:49 Ingo Molnar
2011-11-07 19:00 ` Linus Torvalds
2011-11-07 19:50 ` Ingo Molnar
2011-08-22 17:00 Ingo Molnar
2011-08-11 8:17 Ingo Molnar
2011-07-07 18:11 Ingo Molnar
2011-06-19 8:44 Ingo Molnar
2011-06-13 9:53 Ingo Molnar
2011-06-08 13:46 Ingo Molnar
2011-05-28 16:34 Ingo Molnar
2011-05-24 2:41 Ingo Molnar
2011-05-23 13:41 Ingo Molnar
2011-05-23 22:10 ` Eric Dumazet
2011-05-23 22:19 ` Frederic Weisbecker
2011-05-23 22:22 ` Eric Dumazet
2011-05-20 17:18 Ingo Molnar
2011-05-17 22:07 Ingo Molnar
2011-05-07 18:20 Ingo Molnar
2011-04-29 18:17 Ingo Molnar
2011-04-22 13:42 Ingo Molnar
2011-04-19 15:56 Ingo Molnar
2011-04-16 10:03 Ingo Molnar
2011-04-07 17:48 Ingo Molnar
2011-04-02 10:25 Ingo Molnar
2011-03-25 13:11 Ingo Molnar
2011-03-10 7:53 Ingo Molnar
2011-02-28 17:34 Ingo Molnar
2011-02-22 16:03 Ingo Molnar
2011-02-15 16:58 Ingo Molnar
2011-02-06 11:27 Ingo Molnar
2011-02-03 15:47 Ingo Molnar
2011-01-24 13:34 Ingo Molnar
2011-01-24 19:48 ` Linus Torvalds
2011-01-24 20:07 ` Ingo Molnar
2011-01-24 20:11 ` Ingo Molnar
2011-01-24 20:17 ` Ingo Molnar
2011-01-24 20:17 ` Linus Torvalds
2011-01-24 20:27 ` Linus Torvalds
2011-01-24 20:38 ` Arnaldo Carvalho de Melo
2011-01-24 21:13 ` Linus Torvalds
2011-01-24 21:25 ` Ingo Molnar
2011-01-24 22:00 ` Arnaldo Carvalho de Melo
2011-01-25 0:16 ` Ingo Molnar
2011-01-24 20:37 ` Davidlohr Bueso
2011-01-24 20:14 ` Arnaldo Carvalho de Melo
2011-01-18 18:59 Ingo Molnar
2011-01-18 9:42 Ingo Molnar
2011-01-15 15:24 Ingo Molnar
2011-01-11 11:32 Ingo Molnar
2011-01-03 19:04 Ingo Molnar
2010-12-23 12:56 Ingo Molnar
2010-12-19 15:34 Ingo Molnar
2010-12-08 7:55 Ingo Molnar
2010-11-28 17:36 Ingo Molnar
2010-11-26 13:20 Ingo Molnar
2010-11-11 10:38 Ingo Molnar
2010-10-30 18:21 Ingo Molnar
2010-10-13 15:21 Ingo Molnar
2010-10-05 14:49 Ingo Molnar
2010-09-26 8:38 Ingo Molnar
2010-09-21 19:39 Ingo Molnar
2010-09-10 14:26 Ingo Molnar
2010-08-25 17:44 Ingo Molnar
2010-08-24 19:06 Ingo Molnar
2010-08-19 14:55 Ingo Molnar
2010-08-18 8:14 Ingo Molnar
2010-07-23 19:41 Ingo Molnar
2010-07-16 17:30 Ingo Molnar
2010-07-08 4:36 Frederic Weisbecker
2010-07-08 4:40 ` Frederic Weisbecker
2010-07-08 6:36 ` Ingo Molnar
2010-07-04 20:24 Ingo Molnar
2010-06-10 10:25 Ingo Molnar
2010-06-02 12:28 Ingo Molnar
2010-05-31 23:02 Frederic Weisbecker
2010-06-01 6:59 ` Ingo Molnar
2010-05-30 19:27 Ingo Molnar
2010-05-20 9:44 Frederic Weisbecker
2010-05-20 12:40 ` Ingo Molnar
2010-05-11 19:18 Ingo Molnar
2010-05-12 0:39 ` Linus Torvalds
2010-04-06 17:49 Ingo Molnar
2010-04-04 10:15 Ingo Molnar
2010-04-03 10:47 Frederic Weisbecker
2010-03-28 5:11 Frederic Weisbecker
2010-03-29 3:33 ` Ingo Molnar
2010-03-26 15:16 Ingo Molnar
2010-03-16 16:06 Ingo Molnar
2010-03-11 19:12 Ingo Molnar
2010-02-22 16:50 Ingo Molnar
2010-02-22 17:01 ` Linus Torvalds
2010-02-22 17:15 ` Frederic Weisbecker
2010-02-14 9:06 Ingo Molnar
2010-01-31 17:32 Ingo Molnar
2010-01-21 15:38 Ingo Molnar
2009-12-31 12:00 Ingo Molnar
2009-12-18 18:59 Ingo Molnar
2009-09-22 7:51 Ingo Molnar
2009-09-22 14:49 ` Linus Torvalds
2009-09-22 14:59 ` Ingo Molnar
2009-09-22 15:13 ` Linus Torvalds
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