In chasing down bottlenecks in our native application for Xeon Phi, I run a test to understand NFS and network performance.
Surprisingly, NFS shows throughput to the host of only 13-16 MB/sec - one can see the memory usage on the card go quickly up as the buffers are filled and then the file write slows down.
A measurement of TCP and UDP throughput with netcat showed only 20 MB/sec. Using netcat source/receive on the same Xeon Phi (i.e. local transfers only) showed 27-28 MB/sec.
For comparison the BusSpeedDownload_pragma and BusSpeedReadback_pragma show transfer rates of at least 100 MB/sec in the slowest case (1KB size) and go up to 6 GB/sec.
Any suggestions on what settings I need to change to improve NFS performance ?
Thank you !