From: Ingo Molnar <mingo@elte.hu>
To: "Steven Rostedt" <rostedt@goodmis.org>,
"Frédéric Weisbecker" <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>
Subject: [performance problem] CONFIG_DYNAMIC_FTRACE: Increased kernel build times
Date: Fri, 23 Oct 2009 09:45:33 +0200 [thread overview]
Message-ID: <20091023074533.GA10067@elte.hu> (raw)
Steve,
i did an 64-bit allyesconfig build test (with debug_info disabled), with
and without CONFIG_DYNAMIC_FTRACE set.
The build time results are:
-CONFIG_DYNAMIC_FTRACE: 266.30
+CONFIG_DYNAMIC_FTRACE: 296.07 (+11.2%)
So we get more than 10% build time overhead.
That's quite high - higher than what i remember having measured
originally when the first iteration of the mcount code went in.
This extra overhead comes from the mcount post-processing script
(scripts/recordmcount.pl) that runs objcopy as well and is written in
Perl. I think this whole angle needs to be improved - 10% is way too
high of a price to pay.
Ingo
next reply other threads:[~2009-10-23 7:45 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-23 7:45 Ingo Molnar [this message]
[not found] ` <520f0cf10910230307k91d0c80sa3d69bcd74d6e1f1@mail.gmail.com>
2009-10-23 10:18 ` [performance problem] CONFIG_DYNAMIC_FTRACE: Increased kernel build times John Kacur
2009-10-23 10:37 ` Ingo Molnar
2009-10-23 13:18 ` Steven Rostedt
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=20091023074533.GA10067@elte.hu \
--to=mingo@elte.hu \
--cc=fweisbec@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=rostedt@goodmis.org \
--cc=tglx@linutronix.de \
/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