Jesper,

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As described in Section ?? (Section 3.7), performance on many systems can be improved by overlapping communication and computation. Nonblocking collectives combine the potential benefits of nonblocking point-to-point operations to exploit overlap and to avoid synchronization with the optimized implementation and message scheduling I'm not sure "optimized implementation" here really conveyes to the user the advantage of NBCs hmm, this seems fine to me - you can propose a better wording, but I think it's of marginal importance.

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provided by collective operations [1,4]. One way of doing this would be to perform a blocking collective operation in a separate thread. An alternative mechanism that often leads to better performance (e.g., avoids context switching, scheduler overheads, and thread management) is to use nonblocking collective communication [2]. "the use of" I'd prefer to stay consistent to p47:46

Best, Torsten -- bash$ :(){ :|:&};: --------------------- http://www.unixer.de/ ----- Torsten Hoefler | Postdoctoral Researcher Open Systems Lab | Indiana University 150 S. Woodlawn Ave. | Bloomington, IN, 474045, USA Lindley Hall Room 135 | +01 (812) 855-3608