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From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: rostedt <rostedt@goodmis.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>,
	linux-kernel@vger.kernel.org,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: [RFC][BUG] tracer: Fails to work
Date: Thu, 28 Jan 2016 14:38:16 +0000 (UTC)	[thread overview]
Message-ID: <1616014588.6697.1453991896740.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <20160128135733.GQ6356@twins.programming.kicks-ass.net>

----- On Jan 28, 2016, at 8:57 AM, Peter Zijlstra peterz@infradead.org wrote:

> On Thu, Jan 28, 2016 at 01:38:00PM +0000, Mathieu Desnoyers wrote:
> 
>> Thoughts ?
> 
> So ideally dumping the trace data would not depend on any of that,
> because I can break it all :-)
> 
> Not being able to access the trace data completely and utterly defeats
> the purpose of having a tracer in the first place.

One item I have on my todo list is to allow mapping
the tracer buffers (lttng in my case) onto RAM that
persists across reboots/kexec using dax and the pmem
driver. Since the original system is clearly inactive
after a reboot, we can read the buffers from memory
without caring about synchronization.

That would be one possible way of handling your
snapshot-of-buggy-kernel-trace-buffers use-case.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

  parent reply	other threads:[~2016-01-28 14:38 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-28  8:08 [RFC][BUG] tracer: Fails to work Peter Zijlstra
2016-01-28 13:38 ` Mathieu Desnoyers
2016-01-28 13:57   ` Peter Zijlstra
2016-01-28 14:18     ` Steven Rostedt
2016-01-28 14:38     ` Mathieu Desnoyers [this message]
2016-01-28 14:47       ` Peter Zijlstra
2016-01-28 14:53         ` Mathieu Desnoyers
2016-01-28 15:29           ` Peter Zijlstra
2016-01-28 15:55             ` Steven Rostedt

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