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

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Date:	Sun, 21 Dec 2008 11:12:26 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Frédéric Weisbecker <fweisbec@...il.com>
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


* 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
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