Re: [PATCH 00/13] perf_events: add support for sampling taken branches(v3)

[Arun Sharma]

On 1/27/12 4:09 AM, Peter Zijlstra wrote:
> > Here is a kernel example, where we want to sample indirect calls:
> > $ perf record -a -C 1 -b ind_call -e r1c4:k sleep 10
> > $ perf report -b
> > #
> > # Overhead  Source Symbol               Target Symbol
> > # ........  ..........................  ..........................
> > #
> >      36.36%  [k] __delay                 [k] delay_tsc
> >       9.09%  [k] ktime_get               [k] read_tsc
> >       9.09%  [k] getnstimeofday          [k] read_tsc
> >       9.09%  [k] notifier_call_chain     [k] tick_notify
> >       4.55%  [k] cpuidle_idle_call       [k] intel_idle
> >       4.55%  [k] cpuidle_idle_call       [k] menu_reflect
> >       2.27%  [k] handle_irq              [k] handle_edge_irq
> >       2.27%  [k] ack_apic_edge           [k] native_apic_mem_write
> >       2.27%  [k] hpet_interrupt_handler  [k] hrtimer_interrupt
> >       2.27%  [k] __run_hrtimer           [k] watchdog_timer_fn
> >       2.27%  [k] enqueue_task            [k] enqueue_task_rt
> >       2.27%  [k] try_to_wake_up          [k] select_task_rq_rt
> >       2.27%  [k] do_timer                [k] read_tsc
> >
> > Due to HW limitations, branch filtering may be approximate on
> > Core, Atom processors. It is more accurate on Nehalem, Westmere
> > and best on Sandy Bridge.
>
> Can I have you ACK on this userspace stuff (patches 11-13)?

While the current "Source -> Target" based UI works well for many cases, 
it'd be nice to have "-g -b any_call" to result in a callgraph like 
output, so for userspace programs compiled without frame pointers, we 
get a limited callgraph.

 -Arun
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