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Subject: Re: [OMPI users] openmpi (1.2.8 or above) and Intel composer XE 2011 (aka 12.0)
From: Marcus R. Epperson (mrepper_at_[hidden])
Date: 2011-05-11 18:00:43


I've seen the same thing when I build openmpi 1.4.3 with Intel 12, but only when I have -O2 or -O3 in CFLAGS. If I drop it down to -O1 then the collectives hangs go away. I don't know what, if anything, the higher optimization buys you when compiling openmpi, so I'm not sure if that's an acceptable workaround or not.

My system is similar to yours - Intel X5570 with QDR Mellanox IB running RHEL 5, Slurm, and these openmpi btls: openib,sm,self. I'm using IMB 3.2.2 with a single iteration of Barrier to reproduce the hang, and it happens 100% of the time for me when I invoke it like this:

# salloc -N 9 orterun -n 65 ./IMB-MPI1 -npmin 64 -iter 1 barrier

The hang happens on the first Barrier (64 ranks) and each of the participating ranks have this backtrace:

__poll (...)
poll_dispatch () from [instdir]/lib/libopen-pal.so.0
opal_event_loop () from [instdir]/lib/libopen-pal.so.0
opal_progress () from [instdir]/lib/libopen-pal.so.0
ompi_request_default_wait_all () from [instdir]/lib/libmpi.so.0
ompi_coll_tuned_sendrecv_actual () from [instdir]/lib/libmpi.so.0
ompi_coll_tuned_barrier_intra_recursivedoubling () from [instdir]/lib/libmpi.so.0
ompi_coll_tuned_barrier_intra_dec_fixed () from [instdir]/lib/libmpi.so.0
PMPI_Barrier () from [instdir]/lib/libmpi.so.0
IMB_barrier ()
IMB_init_buffers_iter ()
main ()

The one non-participating rank has this backtrace:

__poll (...)
poll_dispatch () from [instdir]/lib/libopen-pal.so.0
opal_event_loop () from [instdir]/lib/libopen-pal.so.0
opal_progress () from [instdir]/lib/libopen-pal.so.0
ompi_request_default_wait_all () from [instdir]/lib/libmpi.so.0
ompi_coll_tuned_sendrecv_actual () from [instdir]/lib/libmpi.so.0
ompi_coll_tuned_barrier_intra_bruck () from [instdir]/lib/libmpi.so.0
ompi_coll_tuned_barrier_intra_dec_fixed () from [instdir]/lib/libmpi.so.0
PMPI_Barrier () from [instdir]/lib/libmpi.so.0
main ()

If I use more nodes I can get it to hang with 1ppn, so that seems to rule out the sm btl (or interactions with it) as a culprit at least.

I can't reproduce this with openmpi 1.5.3, interestingly.

-Marcus

On 05/10/2011 03:37 AM, Salvatore Podda wrote:
> Dear all,
>
> we succeed in building several version of openmpi from 1.2.8 to 1.4.3
> with Intel composer XE 2011 (aka 12.0).
> However we found a threshold in the number of cores (depending from the
> application: IMB, xhpl or user applications
> and form the number of required cores) above which the application hangs
> (sort of deadlocks).
> The building of openmpi with 'gcc' and 'pgi' does not show the same limits.
> There are any known incompatibilities of openmpi with this version of
> intel compiilers?
>
> The characteristics of our computational infrastructure are:
>
> Intel processors E7330, E5345, E5530 e E5620
>
> CentOS 5.3, CentOS 5.5.
>
> Intel composer XE 2011
> gcc 4.1.2
> pgi 10.2-1
>
> Regards
>
> Salvatore Podda
>
> ENEA UTICT-HPC
> Department for Computer Science Development and ICT
> Facilities Laboratory for Science and High Performace Computing
> C.R. Frascati
> Via E. Fermi, 45
> PoBox 65
> 00044 Frascati (Rome)
> Italy
>
> Tel: +39 06 9400 5342
> Fax: +39 06 9400 5551
> Fax: +39 06 9400 5735
> E-mail: salvatore.podda_at_[hidden]
> Home Page: www.cresco.enea.it
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