Benefits of Quadrics Scatter / Gather to PVFS 2

Noncontiguous IO access is the main access pattern in scientific applications. We have designed an algorithm that supports zerocopy noncontiguous PVFS2 IO using a software scatter/gather mechanism over Quadrics. To investigate what impact Quadrics scatter/gather mechanism can have on PVFS2 IO accesses, in this paper, we perform an indepth evaluation of the scatter/gather mechanism. We also study how much this mechanism can improve on the performance of scientific applications. Our performance evaluation indicates that Quadrics scatter/gather is beneficial to PVFS2 IO bandwidth. The performance of an application benchmark, MPITile-IO, can be improved by 113% and 66% in terms of aggregated read and write bandwidth, respectively. Moreover, our implementation significantly outperforms an implementation of PVFS2 over InfiniBand, which does This research is supported in part by a DOE grant #DE-FC02-01ER25506 and NSF Grants #CCR0311542, #CNS-0403342 and #CNS-0509452. not support zero-copy noncontiguous IO.