linux-kernel - Re: [PATCH 1/2] ftrace: Add duration filtering to function graph tracer

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] [day] [month] [year] [list]

Date:	Mon, 6 Jul 2009 19:22:13 -0700
From:	Tim Bird <tim.bird@...sony.com>
To:	Steven Rostedt <rostedt@...dmis.org>
CC:	linux kernel <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH 1/2] ftrace: Add duration filtering to function graph
 tracer

Steven Rostedt wrote:
> On Mon, 6 Jul 2009, Tim Bird wrote:
>> Another thing I thought of was to not commit the entry event until function
>> exit.  I'm not sure the ring buffer supports having an entry outstanding for
>> long periods of time, though. This would, I believe, hold readers at the entries for
>> the last 'completed' functions, which might solve reader/writer races.
> 
> Heh, I doubt that would be acceptable. The problem is that between reserve 
> and commit, we disable preemption. Thus every function (even the scheduler 
> itself) would have preemption disabled ;-)

Doh!  I think I saw that, but only had a vague recollection of it.
Yeah, that would be a problem ;-)

I'll give the issues some more thought, and see if I can come
up with something.

Thanks for the feedback.
 -- Tim

=============================
Tim Bird
Architecture Group Chair, CE Linux Forum
Senior Staff Engineer, Sony Corporation of America
=============================

--
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/