linux-kernel - Re: [PATCH v2] tracing/function-graph-tracer: prevent from hrtimer interrupt infinite loop

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Date:	Mon, 22 Dec 2008 11:46:47 +0100
From:	"Frédéric Weisbecker" <fweisbec@...il.com>
To:	"Ingo Molnar" <mingo@...e.hu>
Cc:	"Thomas Gleixner" <tglx@...utronix.de>,
	"Steven Rostedt" <rostedt@...dmis.org>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Linux Kernel" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] tracing/function-graph-tracer: prevent from hrtimer interrupt infinite loop

2008/12/21 Frédéric Weisbecker <fweisbec@...il.com>:
> 2008/12/21 Ingo Molnar <mingo@...e.hu>:
>>
>> * Ingo Molnar <mingo@...e.hu> wrote:
>>
>>> btw., a graph-tracer buglet i noticed:
>>
>> another thing. I turned off all the options that come ahead of the 'meat'
>> of the trace data:
>>
>> # cat /debug/tracing/trace_options
>> print-parent nosym-offset nosym-addr noverbose noraw nohex nobin noblock
>> nostacktrace nosched-tree ftrace_printk noftrace_preempt nobranch annotate
>> nouserstacktrace nosym-userobj printk-msg-only nofuncgraph-overrun
>> nofuncgraph-cpu nofuncgraph-overhead nofuncgraph-proc
>>
>> but i still got the 'duration' field printed:
>>
>> # tracer: function_graph
>> #
>> # DURATION            FUNCTION CALLS
>> #     |               |   |   |   |
>>
>> 0.865 us    |    }
>>            |    alloc_page_vma() {
>> 0.295 us    |      get_vma_policy();
>> 0.268 us    |      policy_zonelist();
>>            |      __alloc_pages_internal() {
>> 0.257 us    |        __might_sleep();
>>            |        get_page_from_freelist() {
>>
>>
>> i'd have expected to only see the flow of execution as it happens.
>>
>>        Ingo
>>
>
>
> Strange. I will test that.
>

Did I say it was strange? No it isn't, there is no option to turn off
the duration :-)
I will add one.
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