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