HI Gilles, First a disclaimer - I do not know what the intended design was nor where the design document for this feature is located.
However, I would certainly prefer that if the communicator size wasn't specifically specified in the rule file, a fall back do-no-harm algorithm would be selected. Following the KISS principal I would go with 2) returning a NULL rule when there is no matching size in the rule file for the communicator in question. Howard 2015-05-19 20:05 GMT-06:00 Gilles Gouaillardet <gil...@rist.or.jp>: > Folks, > > this is a follow-up of a discussion on the user ML started at > http://www.open-mpi.org/community/lists/users/2015/05/26882.php > > 1) it turns out the dynamic rule filename must be "sorted" : > - rules must be sorted by communicator size > - within a given communicator size, rules must be sorted by message size > > if not, some rules are silently skipped, which is counter intuitive imho. > > > 2) the algo picks the rule with the higher communicator size less or equal > than the current communicator size (same thing for message size). > The exception is if there are no such rule, the first rule is selected. > for example, if the config file has rules for comm size 4, 8 and 16 > comm size 4 => pick rule for comm size 4 > comm size 5 => pick rule for comm 4 > comm size 8 => pick rule for comm 8 > *but* > comm size 2 => pick rule for comm size 4 (!) > imho, this is also counter intuitive. > i would have expected no rule is picked and the default behaviour is used. > > Same thing applies for message sizes. > > Is this the intended design ? > > 1) can be solved by inserting some qsort calls after parsing the config > file. > 2) can be solved by returning a NULL rule instead of the first rule ( or > by automatically inserting a rule for comm size 0 (and message size 0) if > no such rule is present in the config file). > > any thoughts ? > > Cheers, > > Gilles > _______________________________________________ > devel mailing list > de...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/devel > Link to this post: > http://www.open-mpi.org/community/lists/devel/2015/05/17425.php >
