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Subject: Re: [OMPI users] Factor of 10 loss in performance with 1.3.x
From: Iain Bason (Iain.Bason_at_[hidden])
Date: 2009-04-07 11:22:25


On Apr 7, 2009, at 11:00 AM, Eugene Loh wrote:

> Iain Bason wrote:
>
>> There are a bunch changes in the shared memory module between
>> 1.2.9 and 1.3.1. One significant change is the introduction of
>> the "sendi" internal interface. I believe George Bosilca did the
>> initial implementation. This is just a wild guess, but maybe
>> there is something about sendi that increases latency when using
>> the shared memory module.
>
> But the sm BTL doesn't expose its sendi function, which puts it in
> the same camp as most BTLs.

Ah, right. I didn't notice that your change to expose it is not in
1.3.1.

There are a bunch of other changes. I count 53 revisions in all to
btl_sm.c, though doubtless many of them are either trivial or related
to initialization rather than sending or receiving messages.

But maybe Steve should try 1.3.2 instead? Does that have your
improvements in it?

> And the slowdown doesn't seem to be observed by anyone other than
> Steve and his colleague?

It would be useful to know who else has compared these two revisions.

Iain