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 jsquy...@cisco.com For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
