how does the topology of the barrier impact efficiency?
yey1
@gogogo I think it was discussed in Lecture 17. For example, a centralized barrier will have a high contention. It is better to design a barrier based on interconnect topology.
carnegieigenrac
What exactly is a hypercube barrier? Does it mean that every thread sends notifies every other thread that it has reached the barrier? In that case it just seems like it would be a less efficient version of the linear barrier.
bpr
@carnegieigenrac, as stated in lecture, it was not clear from the code how exactly the tree, hypercube, and hierarchical barriers differ. Effectively they are different k-nary tree designs. The takeaway was that the OpenMP runtime has some choice without requiring the user to properly implement appropriate barriers for the underlying system.
how does the topology of the barrier impact efficiency?
@gogogo I think it was discussed in Lecture 17. For example, a centralized barrier will have a high contention. It is better to design a barrier based on interconnect topology.
What exactly is a hypercube barrier? Does it mean that every thread sends notifies every other thread that it has reached the barrier? In that case it just seems like it would be a less efficient version of the linear barrier.
@carnegieigenrac, as stated in lecture, it was not clear from the code how exactly the tree, hypercube, and hierarchical barriers differ. Effectively they are different k-nary tree designs. The takeaway was that the OpenMP runtime has some choice without requiring the user to properly implement appropriate barriers for the underlying system.