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Re: Using systemtap on MPI applications
- From: fche at redhat dot com (Frank Ch. Eigler)
- To: "Olausson, Bjoern" <contactme at olausson dot de>
- Cc: systemtap at sourceware dot org
- Date: Tue, 15 Mar 2016 15:09:50 -0400
- Subject: Re: Using systemtap on MPI applications
- Authentication-results: sourceware.org; auth=none
- References: <CAE7O3Td1P1jFFbbBFu5k+uu8w8Zw9+fSgRYJqc7d4H57dAV09A at mail dot gmail dot com>
Hi -
"Olausson, Bjoern" wrote:
> [...]
> I am curious if there is a smart way to trace (basically IO) for MPI
> applications running on multiple nodes?
>
> I guess it would be possible to either run stap globally or run
> "mpirun <options> stap script.stp -c mpi-application"
> [...]
That would be the brute-force method. It would require installing the
compiler etc. on all the hosts, unless you run a central stap-server
instance to do the compilation part of the work (passes 1-4).
Another possibility now is to use "stap --remote HOST1 --remote HOST2
..." from a central box, which internally does "ssh HOST1 stapsh" to
maintain a two-way link, and perform remote execution (pass 5).
It would be nice if stap --remote learned about mpi (openmpi?), so as
to use mpirun or similar to manage remote startup of stapsh and
multiplex stdin/stdout/stderr communications with all the hosts in your
hostfile:
% stap --remote mpi:/path/to/hostfile
Or even
% stap --remote mpirun:HOST1 --remote mpirun:HOST2
may be worth doing, using individual "mpirun -H" jobs per host.
- FChE