Open MPI logo

Open MPI User's Mailing List Archives

  |   Home   |   Support   |   FAQ   |  

This web mail archive is frozen.

This page is part of a frozen web archive of this mailing list.

You can still navigate around this archive, but know that no new mails have been added to it since July of 2016.

Click here to be taken to the new web archives of this list; it includes all the mails that are in this frozen archive plus all new mails that have been sent to the list since it was migrated to the new archives.

Subject: Re: [OMPI users] Need Performance estimation of MPI_Bcast
From: Jeffrey Squyres (jsquyres_at_[hidden])
Date: 2012-04-04 09:35:56


It's a bit more complicated than that; there are many factors involved:

- how many peer MPI processes are involved in the broadcast
- how many of those peers are local (and will likely communicate via shared memory, not a network device) and how many are remote
- what broadcast algorithm is used (there are many)

So the simplistic logp model won't help you here -- you'll need to be more complicated, and/or dig into the academic papers on these kinds of things.

On Apr 4, 2012, at 9:11 AM, anas trad wrote:

> Hi Envoyé ,
>
> Thanks for the reply but I want to estimate the time of executing MPI_Bcast function by mathmatics. I found that we can achieve this by using LogGP model with this equation:
>
> T = ceil(log2p) . (L + 2 · o + (n − 1) · G
>
> but that does not give good accuracy for time evaluation.
>
>
>
> --- On Wed, 4/4/12, Aurélien Bouteiller <bouteill_at_[hidden]> wrote:
>
> From: Aurélien Bouteiller <bouteill_at_[hidden]>
> Subject: Re: [OMPI users] Need Performance estimation of MPI_Bcast
> To: "Open MPI Users" <users_at_[hidden]>
> Cc: "users_at_[hidden]" <users_at_[hidden]>
> Date: Wednesday, April 4, 2012, 3:50 PM
>
> You can use the intel mpi benchmark, or skampi. These two programs are designed to evaluate Moi performance.
>
> Envoyé de mon iPad
>
> Le 2012-04-04 à 08:46, anas trad <tradat84_at_[hidden]> a écrit :
>
>> Hi all,
>>
>> I need to know the time estimation of executing MPI_Bcast function on Neolith Cluster. Please, can anyone show me how to achieve that.
>>
>> Thanks,
>> Anas
>>
>> _______________________________________________
>> users mailing list
>> users_at_[hidden]
>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>
> -----Inline Attachment Follows-----
>
> _______________________________________________
> users mailing list
> users_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/users
> _______________________________________________
> users mailing list
> users_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/users

-- 
Jeff Squyres
jsquyres_at_[hidden]
For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/