Sorry, I should have included the link containing the discussion of
the plot.
http://www.open-mpi.org/community/lists/devel/2010/06/8078.php
--
Samuel K. Gutierrez
Los Alamos National Laboratory
On Aug 12, 2010, at 11:20 AM, Terry Dontje wrote:
> Sorry Rich, I didn't realize there was a graph attached at the end
> of message. In other words my comments are not applicable because I
> really didn't know you were asking about the graph. I agree it
> would be nice to know what the graph was plotting.
>
> --td
> Terry Dontje wrote:
>>
>> Graham, Richard L. wrote:
>>>
>>> Stupid question:
>>> What is being plotted, and what are the units ?
>>>
>>> Rich
>>>
>> MB of Resident and Shared memory as gotten from top (on linux).
>> The values for each of the processes run cases seem to be the same
>> between posix, mmap and sysv.
>>
>> --td
>>> On 8/11/10 3:15 PM, "Samuel K. Gutierrez" <samuel_at_[hidden]> wrote:
>>>
>>> Hi Terry,
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Aug 11, 2010, at 12:34 PM, Terry Dontje wrote:
>>>
>>>
>>> I've done some minor testing on Linux looking at resident and
>>> shared memory sizes for np=4, 8 and 16 jobs. I could not see any
>>> appreciable differences in sizes in the process between sysv,
>>> posix or mmap usage in the SM btl.
>>>
>>> So I am still somewhat non-plussed about making this the
>>> default. It seems like the biggest gain out of using posix might
>>> be one doesn't need to worry about the location of the backing
>>> file. This seems kind of frivolous to me since there is a warning
>>> that happens if the backing file is not memory based.
>>>
>>> If I'm not mistaken, the warning is only issued if the backing
>>> files is stored on the following file systems: Lustre, NFS,
>>> Panasas, and GPFS (see: opal_path_nfs in opal/util/path.c).
>>> Based on the performance numbers that Sylvain provided on June 9th
>>> of this year (see attached), there was a performance difference
>>> between mmap on /tmp and mmap on a tmpfs-like file system (/dev/
>>> shm in that particular case). Using the new POSIX component
>>> provides us with a portable way to provide similar shared memory
>>> performance gains without having to worry about where the OMPI
>>> session directory is rooted.
>>>
>>> --
>>> Samuel K. Gutierrez
>>> Los Alamos National Laboratory
>>>
>>> [cid:3364459484_11867134]
>>>
>>>
>>> I still working on testing the code on Solaris but I don't
>>> imagine I will see anything that will change my mind.
>>>
>>> --td
>>>
>>> Samuel K. Gutierrez wrote:
>>> Hi Rich,
>>>
>>> It's a modification to the existing common sm component. The
>>> modifications do include the addition of a new POSIX shared memory
>>> facility, however.
>>>
>>> Sam
>>>
>>> On Aug 11, 2010, at 10:05 AM, Graham, Richard L. wrote:
>>>
>>>
>>> Is this a modification of the existing component, or a new
>>> component ?
>>>
>>> Rich
>>>
>>>
>>> On 8/10/10 10:52 AM, "Samuel K. Gutierrez" <samuel_at_[hidden]> <mailto:samuel_at_[hidden]
>>> > wrote:
>>>
>>> Hi,
>>>
>>> I wanted to give everyone a heads-up about a new POSIX shared
>>> memory
>>> component
>>> that has been in the works for a while now and is ready to be
>>> pushed
>>> into the
>>> trunk.
>>>
>>> http://bitbucket.org/samuelkgutierrez/ompi_posix_sm_new
>>>
>>> Some highlights:
>>> o New posix component now the new default.
>>> o May address some of the shared memory performance issues
>>> users
>>> encounter
>>> when OMPI's session directories are inadvertently
>>> placed on a non-
>>> local
>>> filesystem.
>>> o Silent component failover.
>>> o In the default case, if the posix component fails
>>> initialization,
>>> mmap will be selected.
>>> o The sysv component will only be queried for selection if it is
>>> placed before
>>> the mmap component (for example, -mca mpi_common_sm
>>> sysv,posix,mmap). In the
>>> default case, sysv will never be queried/selected.
>>> o Per some on-list discussion, now unlinking mmaped file in both
>>> mmap
>>> and posix
>>> components (see: "System V Shared Memory for Open MPI: Request
>>> for
>>> Community
>>> Input and Testing" thread).
>>> o Assuming local process homogeneity with respect to all utilized
>>> shared
>>> memory facilities. That is, if one local process deems a
>>> particular shared
>>> memory facility acceptable, then ALL local processes should be
>>> able to
>>> utilize that facility. As it stands, this is an important point
>>> because one
>>> process dictates to all other local processes which common sm
>>> component will
>>> be selected based on its own, local run-time test.
>>> o Addressed some of George's code reuse concerns.
>>>
>>> If there are no major objections by August 17th, I'll commit the
>>> code
>>> after the
>>> Tuesday morning conference call.
>>>
>>> Thanks!
>>>
>>> --
>>> Samuel K. Gutierrez
>>> Los Alamos National Laboratory
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
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>>>
>>>
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>>>
>>>
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>>>
>>>
>>>
>>>
>>>
>>>
>>>
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>>
>>
>> --
>> <mime-attachment.gif>
>> Terry D. Dontje | Principal Software Engineer
>> Developer Tools Engineering | +1.650.633.7054
>> Oracle - Performance Technologies
>> 95 Network Drive, Burlington, MA 01803
>> Email terry.dontje_at_[hidden]
>>
>
>
> --
> <mime-attachment.gif>
> Terry D. Dontje | Principal Software Engineer
> Developer Tools Engineering | +1.650.633.7054
> Oracle - Performance Technologies
> 95 Network Drive, Burlington, MA 01803
> Email terry.dontje_at_[hidden]
>
> _______________________________________________
> devel mailing list
> devel_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/devel
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