Re: kernel function probe overhead

[Cody Santing <csanting@redhat.com>]

Hello  Aubrey,

>> Ah, I note that we don't track occurrences of lock contention,
>> even though we could.  Opened https://sourceware.org/bugzilla/show_bug.cgi?id=20879
>
> okay, thanks, I'll keep an eye on this ticket.
>

I have yet to update the ticket but I have added tracking of lock
contention.  The number of lock contention occurrences on global
variables will be printed following the probe hit report from the '-t'
option.

>> That inconsistency dramatic contention or caching or some other source
>> of jitter.  Having the variance figure in there would be useful though.
>> Would anyone like to give that a try?  (translate.cxx line 2283ish and
>> runtime/linux/common_session_state.h _stp_stat_init area).
>>

I have also added variance to the '-t' option.  It is immediately
following min/avg/max of each probe.

>
> If there is a patch delivered against git head, I can apply it and
> paste the output here.
>

You should find the patch there.  Give it a shot, if you have any
feedback I would like to hear it.

Thank you,

Cody Santing