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Subject: Re: [OMPI devel] sendi sm BTL function
From: George Bosilca (bosilca_at_[hidden])
Date: 2008-10-10 18:39:46


There is a simple (and good) reason not to have it in the upcoming
release. By lack of time, I didn't manage to test it well enough. As
I'm not 100% confident that it will not create any problems, I
preferred to left it out of the 1.3.

If you want to test it, please fell free to do so. And let me know if
you have any problems.

   george.

On Oct 10, 2008, at 6:03 PM, Eugene Loh wrote:

> Can someone tell me about mca_btl_sm_sendi()? In btl_sm.c, I see
> that it's commented out of the structure "mca_btl_sm".
>
> It seems to me that pingpong latency over shared memory in OMPI
> isn't as fast as certain "competitors". If I put mca_btl_sm_sendi
> back in, it seems to improve the pingpong latency a little. For
> some pingpong test and some hardware and some compiler, etc., etc.,
> I get 953 nsec out of the box and 902 nsec if I use
> mca_btl_sm_sendi. So, it seems to improve latency.
>
> Why is it commented out? E.g., look at btl_sm.c and search for the
> first occurrence of "sendi":
>
> mca_btl_sm_t mca_btl_sm = {
> {
> &mca_btl_sm_component.super,
> ...
> NULL /*mca_btl_sm_sendi*/, /* send immediate */
> ...
> }
> };
>
> (I'm just about to leave for a week, but I look forward to reading
> everyone's insightful comments and lively discussion upon my return.)
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