Pvfs
From BGL
A spot for discussions about PVFS2, the Parallel Virtual File System from MCS. Homepage is at http://www.pvfs.org/pvfs2/
PVFS2 had been successfully mounted across the full rack at Argonne. Periodically we run benchmarks. This page documents our benchmarking efforts
New stuff to try from SSW
- Tune buffers, etc.
- Check Physical wiring
Things we have tried
- CIOD environment variables can have a big impact on bulk IO performance. A CIOD_RDWR_BUFFER_SIZE setting of 4MB seems like a good general value.
- Setting up jumbo frames has improved performance
- CIOD always reports CIOD_RDWR_BUFFER_SIZE as the filesystem size in responses to stat(), regardless of the underlying block size. This is the value that the C stdio routines (e.g. fwrite()) use for buffering their I/O.
- However, very small writes with fwrite() still do have a detrimental effect on performance, even though they do not result in smaller writes to PVFS, since it adds overhead on the I/O node.
