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From: Ingo Molnar <mingo@kernel.org>
To: Vince Weaver <vincent.weaver@maine.edu>
Cc: linux-kernel@vger.kernel.org,
	Steven Rostedt <rostedt@goodmis.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
	Dave Jones <davej@redhat.com>,
	Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: perf/ftrace lockup on 3.12-rc6 with trigger code
Date: Sat, 26 Oct 2013 10:48:36 +0200	[thread overview]
Message-ID: <20131026084836.GC14237@gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.10.1310251726001.31246@vincent-weaver-1.um.maine.edu>


* Vince Weaver <vincent.weaver@maine.edu> wrote:

> I don't know if there are any better ways to try to debug things 
> than the printk route.  Though that has its own problems as the 
> printk's themselves start showing up in the ftrace traces.

One additional brute-force method is earlyprintk=...,keep and 
marking the (handful of) earlyprintk functions (and snprintf) 
notrace, plus turning off printk itself completely.

That gives a completely instrumentation-free and locking-free 
console output function of last resort :-/

Thanks,

	Ingo

  reply	other threads:[~2013-10-26  8:48 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-24 17:30 perf/ftrace lockup on 3.12-rc6 with trigger code Vince Weaver
2013-10-24 18:25 ` Vince Weaver
2013-10-25 10:08   ` Steven Rostedt
2013-10-25 10:19     ` Ingo Molnar
2013-10-25 13:17       ` Vince Weaver
2013-10-25 13:12     ` Vince Weaver
2013-10-25 21:36       ` Vince Weaver
2013-10-26  8:48         ` Ingo Molnar [this message]
2013-11-05 18:06           ` Vince Weaver

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