After handling a request, a sync read thread polls its /dev/fuse fd for
up to fuse-read-spin-us microseconds before blocking in read(). Default
0 (disabled). Measured at 50us (tmpfs branch, direct_io): sequential
128K/1M reads +27-32%, 128K writes +14%, metadata walks +24-32%; no
change on 8 parallel streams or 1M writes. Costs roughly one core on a
busy-but-quiet mount, nothing when idle.
Antonio S. Musumeci
76d3990776