NOTE! This week (June 16-20 2008) there are going to be several commits
each of which change the on-media structure and will require recompilation
of the HAMMER utilities, kernel, and for test filesystems to be
newfs_hammer'd.
This is the second of possibly three or four media changes. I hope
to get them all done this week, and then that will be it for media
changes before the 2.0 release.
Please note that this week testers should expect some instability due
to the complexity of the media changes, but I don't expect it to last
beyond the end of the week.
KNOWN BUGS
* There is currently one known failure case that the FSX test finds, which
I hope to address this week. It is related to the BMAP code.
* In-memory record allocations can still blow out system memory and
cause a kmalloc panic.
* bawrite() sometimes panics due to a race (should get this fixed
tuesday).
REMAINDER OF THIS WEEK
For the rest of this week I will be working on bugs and the remaining
media changes that I wanted to get in. In particular going to a larger
block size (and probably implementing clustered writes), and tuning
the low level storage manager.
I believe that going to the larger blocksize will significantly improve
performance as 64K and 128K single-record writes will cut the B-Tree
overhead down by 200-800% verses the 16K single-record writes HAMMER
does now. This should also, coupled with some work on the low level
allocator, greatly improve random read performance in the blogbench test.
-Matt
Matthew Dillon
<dillon@backplane.com>
