What a re s ome o f t he i mprovements i n g oing f rom t he Harperstown chip to the Nehalem? Th e n umber o f M PI me ssages t hat a n N IC c an ha ndle e ach second is becoming more and more of a...

What a re s ome o f t he i mprovements i n g oing f rom t he

Harperstown chip to the Nehalem?

Th e n umber o f M PI me ssages t hat a n N IC c an ha ndle e ach

second is becoming more and more of a bottleneck on multicore

systems. Th e user can reduct the number of messages sent by

assuring t he b est de composition o n t he n ode. Giv en a n a llMPI app lication u sing 8 M PI t asks o n t he n ode, h ow w ould

the number of messages for one halo exchange change in the

following three scenarios?

a. Th e MPI tasks on the node are not neighbors of other MPI

tasks on the node.

b. Th e MPI tasks on the node are arranged in a 2 × 4 × 1 plane

of a grid.

c. Th e MPI tasks on the node are arranged in a 2 × 2 × 2 cube.