(2013/12/23 22:04), Ingo Molnar wrote:
>
> * Masami Hiramatsu <[email protected]> wrote:
>
>>> I can reproduce one weirdness, with just 13 probes added, 'perf probe
>>> -l' [which should really be 'perf probe list'!] executes very slowly:
>>>
>>> # perf stat --null --repeat 3 perf probe -l
>>>
>>> Performance counter stats for 'perf probe -l' (3 runs):
>>>
>>> 0.763640098 seconds time elapsed
>>> ( +- 1.61% )
>>>
>>> 0.7 seconds is ridiculously long.
>>
>> This comes from the perf-probe's internal issue. It tries to get
>> actual lines and files by using debuginfo. I guess most of the time
>> consumed when processing huge kernel debuginfo.
>
> No, I don't have any debuginfo, I never use it.
Then it should be a performance bug. I need to take a look.
BTW, this is just a bug of perf probe, for example,
# wc -l /sys/kernel/debug/tracing/kprobe_events
3204 /sys/kernel/debug/tracing/kprobe_events
# ./perf stat --null --repeat 3 cat /sys/kernel/debug/tracing/kprobe_events
Performance counter stats for 'cat /sys/kernel/debug/tracing/kprobe_events'
(3 runs):
0.032075943 seconds time elapsed
( +- 38.72% )
So even with 3204 probes, listing the kprobe events only takes 0.03 sec.
Thank you,
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: [email protected]
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