The machines have 4 cores. The THREADS_DEFAULT corresponds to a limit:
the program spawns threads once at a time. So at the beginning, only one
thread performs the ping pong test, then a thread is created and the two
threads run the ping pong test, then a thread is created and 3 threads
run the
Francois,
How many cores do your machines have?
The file specifies THREADS_DEFAULT 16. Does this spawn 16 threads per
MPI rank?
I see crashes when I run this with MX (BTL with mx,sm,self and MTL).
If I change THREADS_DEFAULT to 4, I see crashes with TCP (BTL with
tcp,sm,self) as well.
Here's the program.
It should print something like that:
[1 communicating threads]
[0] 1 2.484936 0.402 0.384
[0] 2 2.478036 0.807 0.770
[0] 4 2.501503 1.599 1.525
[0] 8 2.497516 3.203
I will take a look at the BTL problem. Can you provide a copy of the
benchmarks please.
Thanks,
george.
On Jun 11, 2009, at 16:05 , François Trahay wrote:
concurrent_ping
Oops. Here's the trace using the BTL.
Francois
Scott Atchley wrote:
By specifying --mca pml cm, both traces are using the MTL. To use the
BTL, try:
$ mpiexec --mca btl mx,sm,self -machinefile ./joe -np 2 ./concurrent_ping
or simply:
$ mpiexec -machinefile ./joe -np 2 ./concurrent_ping
Scot
On Jun 11, 2009, at 2:20 PM, François Trahay wrote:
The stack trace is from the MX MTL (I attach the backtraces I get
with both MX MTL and MX BTL)
Here is the program that I use. It is quite simple. It runs ping
pongs concurrently (with one thread per node, then with two threads
per node, e
Based on the stack trace, at one point (depth 4) we are in the MX MTL
and then we call free. It might happens that two threads call free
simultaneously ... It is a guess, as there is not enough information
to corroborate this.
george.
On Jun 11, 2009, at 13:17 , Scott Atchley wrote:
Br
Almost assuredly, the MTL is not thread safe, and such support is
unlikely to happen in the short term. You might be better off
concentrating on the BTL, as George has done significant work on that
front.
Brian
On Jun 11, 2009, at 12:20 PM, François Trahay wrote:
The stack trace is from
The stack trace is from the MX MTL (I attach the backtraces I get with
both MX MTL and MX BTL)
Here is the program that I use. It is quite simple. It runs ping pongs
concurrently (with one thread per node, then with two threads per node,
etc.)
The error occurs when two threads run concurrently.
Brian and George,
I do not know if the stack trace is complete, but I do not see any
mx_* functions called which would indicate a crash inside MX due to
multiple threads trying to complete the same request. It does show an
assert failed.
Francois, is the stack trace from the MX MTL or BTL
Neither the CM PML or the MX MTL has been looked at for thread
safety. There's not much code to cause problems in the CM PML. The
MX MTL would likely need some work to ensure the restrictions Scott
mentioned are met (currently, there's no such guarantee in the MX MTL).
Brian
On Jun 11, 2
The comment on the FAQ (and on the other thread) is only true for some
BTLs (TCP, SM and MX). I don't have resources to test for the others
BTL, it is their developers responsibility to do the required
modifications to make them thread safe.
In addition, I have to confess that I never teste
Francois,
For threads, the FAQ has:
http://www.open-mpi.org/faq/?category=supported-systems#thread-support
It mentions that thread support is designed in, but lightly tested. It
is also possible that the FAQ is out of date and MPI_THREAD_MULTIPLE
is fully supported.
The stack trace below
Well, according to George Bosilca
(http://www.open-mpi.org/community/lists/users/2005/02/0005.php),
threads are supported in OpenMPI.
The program I try to run works with the TCP stack and MX driver is
thread-safe, so i guess the problem comes from the MX BTL or MTL.
Francois
Scott Atchley wr
Hi Francois,
I am not familiar with the internals of the OMPI code. Are you sure,
however, that threads are fully supported yet? I was under the
impression that thread support was still partial.
Can anyone else comment?
Scott
On Jun 8, 2009, at 8:43 AM, François Trahay wrote:
Hi,
I'm en
Hi,
I'm encountering some issues when running a multithreaded program with
OpenMPI (trunk rev. 21380, configured with --enable-mpi-threads)
My program (included in the tar.bz2) uses several pthreads that perform
ping pongs concurrently (thread #1 uses tag #1, thread #2 uses tag #2, etc.)
This prog
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