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SubjectRe: [PATCH -tip v6 00/22] kprobes: introduce NOKPROBE_SYMBOL(), cleanup and fixes crash bugs

* Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> wrote:

> I guess the second reason is why the stap takes so long time to set
> probes. stap tries to register kprobes without disabled flag, that
> means we enables thousands of probes (overheads).
>
> So the similar thing happens when we enables events as below;
>
> # for i in /sys/kernel/debug/tracing/events/kprobes/* ; do date; echo 1 > $i; done
> Wed Jan 29 10:44:50 UTC 2014
> ...
>
> I tried it and canceled after 4 min passed. It enabled about 17k
> events and slowed down my system very much(I almost got hang check
> timer).

Ok, I guess that's the slowdown bug that Frank reported.

> I think we should have some performance statistics (hit count?) and
> if it goes over a threshold, we should stop enabling other events.

That really feels like a hack. How about fixing the root cause? Does
the enabling of all probes have to be so slow?

Thanks,

Ingo


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