Hi -

quoted

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.

It could be, but it feels a bit different.  In my testing from
December, it's as though it wasn't the activated probes *hitting* that
were associated with the slowdown, but them merely being activated.
It was as though something with the kprobes/ftrace probe-registration
code performed a lot more work than it did longer ago.  (One way to
test this could be to be more careful in the selection of kprobes
being enabled.  For examle, emplace thousands, but only unused loaded
modules.)  I'm sorry I didn't get time to investigate further.

- FChE