linux-kernel - Re: [performance problem] CONFIG_DYNAMIC_FTRACE: Increased kernel build times

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.LFD.2.00.0910231211540.3549@localhost.localdomain>
Date:	Fri, 23 Oct 2009 12:18:41 +0200 (CEST)
From:	John Kacur <jkacur@...hat.com>
To:	Ingo Molnar <mingo@...e.hu>
cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [performance problem] CONFIG_DYNAMIC_FTRACE: Increased kernel 
 build times

2009/10/23 Ingo Molnar <mingo@...e.hu> wrote:
> 
> 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.

Hi Ingo, do you still have the profiling data to share with us?
Was the problem more in objcopy / objdump, rather than in the perl script 
itself?

Thanks

John