cvs commit: src/sys/kern init_main.c kern_descrip.c sys_pipe.c uipc_syscalls.c uipc_usrreq.c vfs_syscalls.c src/sys/sys filedesc.h

[Dag-ErlingSmørgrav]

Tim Robbins <tjr at freebsd.org> writes:
> Thanks for committing this. I'm interested, though, what was the reason you
> changed it to use a single bitmap instead of two levels?

The increased complexity didn't actually translate into a performance
improvement.  There was no reason to use two levels instead of one.
The theoretical advantage is logarithmic rather than linear early
growth, but in practice it wasn't noticeable.  The cost of the logic
required to maintain and use the high-level bitmap outweighs the gain
(which is to save a handful of comparisons against zero in the
low-level bitmap).

DES
-- 
Dag-Erling Smørgrav - des at des.no