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Subject: Re: [OMPI devel] RFC: Remove heterogeneous support
From: George Bosilca (bosilca_at_[hidden])
Date: 2014-04-28 11:17:27


I’m not sure how to interpret their claim. They say it has native support for little endian, fact that was true for quite some time (http://en.wikipedia.org/wiki/PowerPC#Endian_modes). Unfortunately, I could not find any indication about the possible overhead of running little-endian applications on a big-endian OS.

  George.

 
On Apr 28, 2014, at 10:09 , Atchley, Scott <atchleyes_at_[hidden]> wrote:

> Hi George,
>
> The Power8 can run in little-endian mode without penalty:
>
> http://www.hpcwire.com/2014/04/23/power8-openpower-might-mean-hpc/
>
> Not saying hetero support is unneeded, but this case may not be it.
>
> Scott
>
> On Apr 24, 2014, at 12:54 PM, George Bosilca <bosilca_at_[hidden]> wrote:
>
>> There seems to be an opportunity to still have heterogeneous environment in the future.
>> http://www.enterprisetech.com/2014/04/23/ibm-google-show-power8-systems-openpower-efforts/
>>
>> I don’t think it is fair to shift the burden on the original developer instead of the committer who broke a feature.
>>
>> George.
>>
>> On Apr 23, 2014, at 09:49 , Jeff Squyres (jsquyres) <jsquyres_at_[hidden]> wrote:
>>
>>> WHAT: Remove data-heterogeneous support from Open MPI
>>>
>>> WHY: No one uses it (it's not the default), it's broken (probably has been for a while)
>>>
>>> WHERE: Datatype engine, some configury, and a few other places
>>>
>>> TIMEOUT: Tuesday teleconf, 6 May 2014 (i.e., 2 weeks from now)
>>>
>>> MORE DETAIL:
>>>
>>> It recently came to my attention that we seem to have some bit rot in the heterogeneous data representation support such that if you configure with --enable-heterogeneous, even if you run on homogeneous machines, you can get segv's with tcp,sm,self.
>>>
>>> The heterogeneous support has never been enabled by default. AFAIK, only Cisco tests it regularly in its MTT. I'm be greatly surprised if many (any?) users use it at all.
>>>
>>> So I have to ask myself: why do we keep this functionality around? It seems like we should delete this code, simplify things a little, and move on.
>>>
>>> Comments?
>>>
>>> --
>>> Jeff Squyres
>>> jsquyres_at_[hidden]
>>> For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
>>>
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>>
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