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Subject: Re: [OMPI devel] RFC: change default for tuned alltoallv to pairwise
From: George Bosilca (bosilca_at_[hidden])
Date: 2012-03-22 15:38:45


On Mar 21, 2012, at 12:14 , Nathan Hjelm wrote:

> What: Change coll tuned default to pairwise exchange
>
> Why: The linear algorithm does not scale to any reasonable number of PEs
>
> When: Timeout in 2 days (Fri)
>
> Is there any reason the default should not be changed?

Nathan,

I can see why people think the linear algorithm is bad. However I think it depends on the application communication pattern in the alltoallv. Do you have any numbers to back your claim?

  george.