- Keep a freelist of component buffer headers, defaulting
to 8 headers per component (tunable with the CCDNBUF
kernel compile option).
- When allocating a component buffer, try to pull a header
off the freelist first, falling back on MALLOC() if the
freelist is empty. Use MALLOC() rather than malloc(),
because it will attempt to short-cut the allocation before
actually making a full-blown malloc() call.
- Keep statistics on how many component buffer headers have
been allocated and how many of those allocations have
resulted in freelist misses.
With these changes, I observed measurable decreases in system and
wall clock time on operations on an 8G ccd, as well as a measurable
drop in the time spent in ccdbuffer() (measured with kernel profiling).
- New metrics handling. Metrics are now kept in the new
`struct disk'. Busy time is now stored as a timeval, and
transfer count in bytes.
- Storage for disklabels is now dynamically allocated, so that
the size of the disk structure is not machine-dependent.
- Several new functions for attaching and detaching disks, and
handling metrics calculation.
Old-style instrumentation is still supported in drivers that did it before.
However, old-style instrumentation is being deprecated, and will go away
once the userland utilities are updated for the new framework.
For usage and architectural details, see the forthcoming disk(9) manual
page.
out by Jochen Pohl in PR #1588. Change the interleave index to an
array of ints rather than an array of chars to avoid losing in the event
one has more than 127 components.
