linux-kernel - Re: perf report fractal output issue

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Date:	Fri, 16 Oct 2009 10:41:26 +1100
From:	Anton Blanchard <anton@...ba.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	mingo@...e.hu, paulus@...ba.org, a.p.zijlstra@...llo.nl,
	linux-kernel@...r.kernel.org
Subject: Re: perf report fractal output issue


Hi,

> > It looks like callchain__fprintf_graph() only prints the callchain if we
> > have at least one rb entry at the top. In my case all the associated
> > backtraces are identical so I assume we dont have to do any splitting.
>
> Hmm, could you please send me a perf.data where you can see that?
> Does that only happen on powerpc?

I can replicate this on x86 by taking a perf.data and truncating it
after the first sample+backtrace:


# wget http://samba.org/~anton/perf_truncated.test


# perf report -i perf_truncated.test -g fractal
...
   100.00%     perf  [kernel]       [k] native_write_msr_safe


# perf report -i perf_truncated.test -g flat
...
   100.00%     perf  [kernel]       [k] native_write_msr_safe
           100.00%
                native_write_msr_safe
                intel_pmu_enable_all
                hw_perf_enable
                perf_enable
                __perf_counter_enable
                smp_call_function_single
                task_oncpu_function_call
                perf_counter_enable
                perf_counter_for_each_child
                perf_ioctl
                vfs_ioctl
                do_vfs_ioctl
                sys_ioctl
                system_call_fastpath
                0x7f00c1857537
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