[caiman-discuss] Final webrevs updated for HSFS readahead changes

[Moinak Ghosh]

I have completed all the updates after the last review comments and 
completed
all my testing. I have done manual tests and Filebench tests on SPARC and
x86. The Filebench tests were also repeated to kmem_flags set to 0x1f  and
checked for correctness and leaks. The fsfuzzer test was run for 10days 
without
issues. The bug is updated.

The updated webrevs are available at:
http://www.genunix.org/distributions/belenix_site//binfiles/hsfswebrev/index.htm

Updated binaries available from:
http://www.genunix.org/distributions/belenix_site//binfiles/hsfs.amd64
http://www.genunix.org/distributions/belenix_site//binfiles/hsfs.sparcv9

This update adds the following changes:

- Incorporate all the review comments.
- Add kstats and SDT probes for debugging purposes. You can copy the
  updated module, mount a DVD and see:
  kstat -m hsfs_fs
  dtrace -l -P sdt | grep hsfs
- SPARC testing was done on a T2000 and it threw up a surprise perf
  issue for the single-stream sequential read and random read tests. It was
  found using standard kmem_alloc for thousands of small allocations of
  size 96 bytes was inefficient. So a kmem_cache was used and it made
  a dramatic difference.
- Removed one unnecessary page_lookup in the readahead path.

As it stands now there is an across the board improvement on all Filebench
tests including the random read tests on both x86 and SPARC.

Regards,
Moinak.