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Subject: Re: [OMPI users] btl_openib_cpc_include rdmacm questions
From: Brock Palen (brockp_at_[hidden])
Date: 2011-05-17 14:02:32


Thanks, I though of looking at ompi_info after I sent that note sigh.

SEND_INPLACE appears to help performance of larger messages in my synthetic benchmarks over regular SEND. Also it appears that SEND_INPLACE still allows our code to run.

We working on getting devs access to our system and code.

Brock Palen
www.umich.edu/~brockp
Center for Advanced Computing
brockp_at_[hidden]
(734)936-1985

On May 16, 2011, at 11:49 AM, George Bosilca wrote:

> Here is the output of the "ompi_info --param btl openib":
>
> MCA btl: parameter "btl_openib_flags" (current value: <306>, data
> source: default value)
> BTL bit flags (general flags: SEND=1, PUT=2, GET=4,
> SEND_INPLACE=8, RDMA_MATCHED=64, HETEROGENEOUS_RDMA=256; flags
> only used by the "dr" PML (ignored by others): ACK=16,
> CHECKSUM=32, RDMA_COMPLETION=128; flags only used by the "bfo"
> PML (ignored by others): FAILOVER_SUPPORT=512)
>
> So the 305 flags means: HETEROGENEOUS_RDMA | CHECKSUM | ACK | SEND. Most of these flags are totally useless in the current version of Open MPI (DR is not supported), so the only value that really matter is SEND | HETEROGENEOUS_RDMA.
>
> If you want to enable the send protocol try first with SEND | SEND_INPLACE (9), if not downgrade to SEND (1)
>
> george.
>
> On May 16, 2011, at 11:33 , Samuel K. Gutierrez wrote:
>
>>
>> On May 16, 2011, at 8:53 AM, Brock Palen wrote:
>>
>>>
>>>
>>>
>>> On May 16, 2011, at 10:23 AM, Samuel K. Gutierrez wrote:
>>>
>>>> Hi,
>>>>
>>>> Just out of curiosity - what happens when you add the following MCA option to your openib runs?
>>>>
>>>> -mca btl_openib_flags 305
>>>
>>> You Sir found the magic combination.
>>
>> :-) - cool.
>>
>> Developers - does this smell like a registered memory availability hang?
>>
>>> I verified this lets IMB and CRASH progress pass their lockup points,
>>> I will have a user test this,
>>
>> Please let us know what you find.
>>
>>> Is this an ok option to put in our environment? What does 305 mean?
>>
>> There may be a performance hit associated with this configuration, but if it lets your users run, then I don't see a problem with adding it to your environment.
>>
>> If I'm reading things correctly, 305 turns off RDMA PUT/GET and turns on SEND.
>>
>> OpenFabrics gurus - please correct me if I'm wrong :-).
>>
>> Samuel Gutierrez
>> Los Alamos National Laboratory
>>
>>
>>>
>>>
>>> Brock Palen
>>> www.umich.edu/~brockp
>>> Center for Advanced Computing
>>> brockp_at_[hidden]
>>> (734)936-1985
>>>
>>>>
>>>> Thanks,
>>>>
>>>> Samuel Gutierrez
>>>> Los Alamos National Laboratory
>>>>
>>>> On May 13, 2011, at 2:38 PM, Brock Palen wrote:
>>>>
>>>>> On May 13, 2011, at 4:09 PM, Dave Love wrote:
>>>>>
>>>>>> Jeff Squyres <jsquyres_at_[hidden]> writes:
>>>>>>
>>>>>>> On May 11, 2011, at 3:21 PM, Dave Love wrote:
>>>>>>>
>>>>>>>> We can reproduce it with IMB. We could provide access, but we'd have to
>>>>>>>> negotiate with the owners of the relevant nodes to give you interactive
>>>>>>>> access to them. Maybe Brock's would be more accessible? (If you
>>>>>>>> contact me, I may not be able to respond for a few days.)
>>>>>>>
>>>>>>> Brock has replied off-list that he, too, is able to reliably reproduce the issue with IMB, and is working to get access for us. Many thanks for your offer; let's see where Brock's access takes us.
>>>>>>
>>>>>> Good. Let me know if we could be useful
>>>>>>
>>>>>>>>> -- we have not closed this issue,
>>>>>>>>
>>>>>>>> Which issue? I couldn't find a relevant-looking one.
>>>>>>>
>>>>>>> https://svn.open-mpi.org/trac/ompi/ticket/2714
>>>>>>
>>>>>> Thanks. In csse it's useful info, it hangs for me with 1.5.3 & np=32 on
>>>>>> connectx with more than one collective I can't recall.
>>>>>
>>>>> Extra data point, that ticket said it ran with mpi_preconnect_mpi 1, well that doesn't help here, both my production code (crash) and IMB still hang.
>>>>>
>>>>>
>>>>> Brock Palen
>>>>> www.umich.edu/~brockp
>>>>> Center for Advanced Computing
>>>>> brockp_at_[hidden]
>>>>> (734)936-1985
>>>>>
>>>>>>
>>>>>> --
>>>>>> Excuse the typping -- I have a broken wrist
>>>>>>
>>>>>> _______________________________________________
>>>>>> users mailing list
>>>>>> users_at_[hidden]
>>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>>>
>>>>>>
>>>>>
>>>>>
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>>>
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>
> George Bosilca
> Research Assistant Professor
> Innovative Computing Laboratory
> Department of Electrical Engineering and Computer Science
> University of Tennessee, Knoxville
> http://web.eecs.utk.edu/~bosilca/
>
>
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