On 03/02/21 10:23, Song Bao Hua (Barry Song) wrote: >> -----Original Message----- >> From: Valentin Schneider [mailto:[email protected]] >> Thoughts? > > I guess the original purpose of overlapping groups is creating as few groups > as possible. If we totally remove overlapping groups, it seems we will create > much more groups? > For example, while node0 begins to build sched_domain for distance 20, it will > add node2, since the distance between node2 and node3 is 15, so while node2 is > added, node3 is also added as node2's lower domain has covered node3. So we > need > two groups only for node0's sched_domain of distance level 20. > +-------+ +--------+ > | | 15 | | > | node0+----------------+ | node1 | > | | | | > +----+--+ XXX--------+ > | XXX > | XX > 20 | 15 XX > | XXX > | X XXX > +----+----XXX +-------+ > | | 15 | node3| > | node2 +-----------------+ | > | | +-------+ > +---------+ > > If we remove overlapping group, we will add a group for node2, another > group for node3. Then we get three groups. > > I am not sure if it is always positive for performance. >
Neither am I! At the same time our strategy for generating groups is pretty much flawed for anything with distance > 2, so I'd like to have a saner setup that doesn't involve fixing groups "after the fact". I have a sort-of-working hack, I'll make this into a patch and toss it out for discussion.
