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Subject: Re: [OMPI devel] [OMPI users] huge VmRSS on rank 0 after MPI_Init when using "btl_openib_receive_queues" option
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2011-07-09 07:13:04

Sorry for the delayed reply.

I'm guessing that there's some kind of rooted collective operation occurring during MPI_INIT. Try doing a 1 byte MPI_GATHER to another rank in MCW (e.g., to rank 5) and see if the VmSS goes to the same size as MCW rank 0.

On Jul 8, 2011, at 5:17 AM, Eloi Gaudry wrote:

> what i cannot understand is the reason why this extra memory would be initialized on proc 0 only.
> as far as i know, this doesn't make sense.
> éloi
>> On 22/04/2011 08:52, Eloi Gaudry wrote:
>>> it varies with the receive_queues specification *and* with the number of mpi processes: memory_consumed = nb_mpi_process * nb_buffers * (buffer_size + low_buffer_count_watermark + credit_window_size )
>>> éloi
>>> On 04/22/2011 12:26 AM, Jeff Squyres wrote:
>>>> Does it vary exactly according to your receive_queues specification?
>>>> On Apr 19, 2011, at 9:03 AM, Eloi Gaudry wrote:
>>>>> hello,
>>>>> i would like to get your input on this:
>>>>> when launching a parallel computation on 128 nodes using openib and the "-mca btl_openib_receive_queues P,65536,256,192,128" option, i observe a rather large resident memory consumption (2GB: 65336*256*128) on the process with rank 0 (and only this process) just after a call to MPI_Init.
>>>>> i'd like to know why the other processes doesn't behave the same:
>>>>> - other processes located on the same nodes don't use that amount of memory
>>>>> - all others processes (i.e. located on any other nodes) neither
>>>>> i'm using OpenMPI-1.4.2, built with gcc-4.3.4 and '--enable-cxx-exceptions --with-pic --with-threads=posix' options.
>>>>> thanks for your help,
>>>>> éloi
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Jeff Squyres
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