FYI, I ran some performance tests for a feature that incorporates
pre-allocation support into linux nfsd. The patch is a
proof-of-concept but the measurements are still relevant for this list.
1. Sequential read throughput with iozone reading a file written
using various pre-allocation sizes through nfsd:
2. Sequential write throughput with iozone over NFS mount with the
nfsd writing the file contents to disk using pre-allocation.
Please see the following thread for more details.
From the write throughput plot, its clear that pre-allocation would be
highly beneficial if the pre-allocation overhead can be reduced.