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Subject: Re: [OMPI devel] v1.5: sigsegv in case of extremely low settings in theSRQs
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2010-06-23 10:51:23


On Jun 23, 2010, at 10:46 AM, Sylvain Jeaugey wrote:

> Why do we want to set this value so low ? Well, just to see if it crashes :-)

That's a good reason! :-)

> More seriously, we're working on lowering the memory usage of the openib BTL, which is achieved at most by having only 1 send queue element (at very large scale, send queues prevail).
>
> This "extreme" configuration used to work with the 1.3/1.4 branches but failed on 1.5.

Cool; thanks for checking!

> Note that recent IB cards having very high issue rates, I don't know if we are often waiting for the send queue to be empty. More importantly, it often prevents remote receive queue to be filled to quickly (which prevents RNR nacks, threads refilling the SRQ, ...). We didn't notice major performance drops with this configuration.

Interesting.

BTW, are you guys waiting for us to commit that, or do we ever give you guys SVN commit access?

-- 
Jeff Squyres
jsquyres_at_[hidden]
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