DragonFly kernel List (threaded) for 2008-06
HEADS UP - HAMMER destabilized for a few days (update 2)
People testing HAMMER are going to have to update both the kernel
and newfs_hammer utility, and newfs_hammer their test filesystems again
I'm afraid. There was a critical bug in newfs_hammer and a CRC
generation bug in the filesystem core.
HAMMER is not yet fully stabilized. I've whacked most of the issues
but FSX still fails occassionally under heavy loads and there
are two assertion panics, all related to the new write-performance
code. I expect to get the panics fixed today and will hopefully track
the bug FSX is revealing down by tomorrow.
Write performance as of commit 53B is now very good. The filesystem
frontend is now able to directly reserve space on the media and flush
its dirty buffers out whereas before it had to queue the dirty buffers
to the backend.
Blogbench did a complete flip.. now random write performance is
incredible but random read performance is suffering (probably due to
the write performance eating up so much of the disk bandwidth).
In general, I am very happy with HAMMER's performance now and do not
expect to have to introduce any new major bits of code on that front.