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Open Source and information security mailing list archives
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Date: Tue, 16 Dec 2008 22:59:41 +0100 From: Ingo Molnar <mingo@...e.hu> To: Frédéric Weisbecker <fweisbec@...il.com> Cc: Steven Rostedt <rostedt@...dmis.org>, Linux Kernel <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] tracing/ftrace: use preempt_enable_no_resched_notrace in ring_buffer_time_stamp() * Frédéric Weisbecker <fweisbec@...il.com> wrote: > 2008/12/16 Steven Rostedt <rostedt@...dmis.org>: > > > > > > On Tue, 16 Dec 2008, Fr?d?ric Weisbecker wrote: > >> > >> The hard reboots I've seen are related to x86-64 while > >> disabling/reenabling a CPU through /sys/device/system/cpu > >> No tracer was enabled at these times (the problem still remains with > >> latest updates on -tip for half an hour). > > > > Do you have STACK_TRACER enabled? > > > > -- Steve > > > > You were right. I've just built a kernel without STACK_TRACER and the > problem disappears... i noticed high stack-tracer overhead too. Which is understandable i guess: the stack tracer keeps the mcount callbacks running all the time and can save the stack backtrace of the highest-stack-usage point in time that the kernel ever has hit in the past. That is a pretty powerful debug capability, with appropriate costs. Ingo -- 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/
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