linux-kernel - Re: [PATCH 00/10][RFC] tracing: Lowering the footprint of TRACE

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

Date:	Wed, 28 Apr 2010 10:45:59 -0400
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	Steven Rostedt <rostedt@...dmis.org>
CC:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Mathieu Desnoyers <compudj@...stal.dyndns.org>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Li Zefan <lizf@...fujitsu.com>, Christoph Hellwig <hch@....de>
Subject: Re: [PATCH 00/10][RFC] tracing: Lowering the footprint of TRACE_EVENTs

Steven Rostedt wrote:
> This is an RFC patch set that also affects kprobes and perf.
> 
> At the Linux Collaboration Summit, I talked with Mathieu and others about
> lowering the footprint of trace events. I spent all of last week
> trying to get the size as small as I could.
> 
> Currently, each TRACE_EVENT() macro adds 1 - 5K per tracepoint. I got various
> results by adding a TRACE_EVENT() with the compiler, depending on
> config options that did not seem related. The new tracepoint I added
> would add between 1 and 5K, but I did not investigate enough to
> see what the true size was.
> 
> What was consistent, was the DEFINE_EVENT(). Currently, it adds
> a little over 700 bytes per DEFINE_EVENT().
> 
> This patch series does not seem to affect TRACE_EVENT() much (had
> the same various sizes), but consistently brings DEFINE_EVENT()s
> down from 700 bytes to 250 bytes per DEFINE_EVENT(). Since syscalls
> use one "class" and are equivalent to DEFINE_EVENT() this can
> be a significant savings.
> 
> With events and syscalls (82 events and 616 syscalls), before this
> patch series, the size of vmlinux was: 16161794, and afterward: 16058182.
> 
> That is 103,612 bytes in savings! (over 100K)
> 
> 
> Without tracing syscalls (82 events), it brought the size of vmlinux
> down from 1591046 to 15999394.
> 
> 22,071 bytes in savings.
> 
> This is just an RFC (for now), to get peoples opinions on the changes.
> It does a bit of rewriting of the CPP macros, just to warning you ;-)

Hm, at least for kprobe tracer, this change is ok, 
even though it isn't much worth as for tracepoints.
I think, if we have ftrace_event_ops, it will help reducing
the size of dynamic events a bit (not so much).


Thank you,


-- 
Masami Hiramatsu
e-mail: mhiramat@...hat.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/