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Re: Using systemtap on MPI applications
- From: "Olausson, Bjoern" <contactme at olausson dot de>
- To: "Frank Ch. Eigler" <fche at redhat dot com>
- Cc: systemtap at sourceware dot org
- Date: Thu, 17 Mar 2016 13:09:48 +0100
- Subject: Re: Using systemtap on MPI applications
- Authentication-results: sourceware.org; auth=none
- References: <CAE7O3Td1P1jFFbbBFu5k+uu8w8Zw9+fSgRYJqc7d4H57dAV09A at mail dot gmail dot com> <y0mh9g7a77l dot fsf at fche dot csb> <CAE7O3TfvL=7YmYeEyo=MrKM7T8ph_PMqgxYGko-BtzyHGLaf4Q at mail dot gmail dot com> <20160316140724 dot GD3854 at redhat dot com>
On Wed, Mar 16, 2016 at 3:07 PM, Frank Ch. Eigler <fche@redhat.com> wrote:
> Hi -
>
>> > "Olausson, Bjoern" wrote:
>
>> Indeed it would be great if stap would be MPI aware in some way.
>
> "patches welcome" :-) we'd be glad to advise, but aren't planning
> to undertake the work ourselves very soon.
>
Understood :-)
>
>> Still there is the issue on how to filter what stap is tracing. How
>> would I tell stap to only focus on one particular executable or PID
>> when using the --remote switch so target() can be used.
>> Any ideas on that?
>
> I believe the "stap -c CMD" and "stap -x PID" options both travel
> through "stap --remote ..." ssh, though of course the former makes a
> lot more sense. The "-c CMD" may be good enough for MPI purposes.
> And there's always filtering from first principles:
>
> if (execname() =~ ".*foo.*" && uid() == 44) { }
>
> - FChE
Excuse that stupid question, but I thought using "-c CMD" will always
instantly execute the CMD, so that would not play will with MPI
executed applications :)
But is there a way to pass a string to stap on which I can apply e.g.
your above filter instead of hardcoding the exec name I want to filter
on?
Cheers and thanks a lot for all your quick answers,
Bjoern