A18: Understanding the Impact of Fat-Tree Network
Locality on Application Performance
SessionPoster Reception
Author
Event Type
ACM Student Research Competition
Poster
Reception
TimeTuesday, November 14th5:15pm -
7pm
LocationFour Seasons Ballroom
DescriptionNetwork congestion can be a significant cause of
performance loss and variability for many message
passing programs. However, few studies have used a
controlled environment with virtually no other
extraneous sources of network traffic to observe the
impact of application placement and multi-job
interactions on overall performance. We study different
placements and pairings for three DOE applications. We
observe that for a job size typical for an LLNL
commodity cluster, the impact of congestion and poor
placement is typically less than 2%, which is less
dramatic than on torus networks. In addition, in most
cases, the cyclic MPI task mapping strategy increases
performance and reduces placement sensitivity despite
also increasing total network traffic. We also found
that the performance difference between controlled
placements and runs scheduled through the batch system
was less than 3%.
Author
