distributed filesystems
Robert Watson
rwatson at FreeBSD.org
Thu Apr 26 09:36:03 UTC 2007
On Wed, 25 Apr 2007, Greg Troxel wrote:
> Good point, and I suspect it isn't that hard. NetBSD is also (finally)
> moving to fine-grained locking.
Given what a long, hard haul that proved for every other operating system thas
has approached the project, I would expect to see results from that project in
the longer, rather than shorter, term.
> I supsect one could either create a coda lock and always grab that, or to
> make locks for each data object (the name cache is probably what's needed -
> everything else is per-vnode and the vnode lock protects most vnode
> changes).
Up-front, I think a global Coda lock protecting things like message queueing
and waiting structures would be fine. Since most vnode operations pass
straight through to the container vnode (or did, when I last worked on Coda),
it could be that no additional locking is required on things like read/write
paths beyond the existing vnode locking.
Any chance you'd have interest in working on this project? :-) While the time
is not yet here, there will come a point where we will be interested in
kicking out file systems that cannot operate without Giant, in the same way
we're now doing that for network stack components. There's a significant
complexity overhead to all the conditional per-filesystem giant acquisition
logic, but it means all file systems will need to be updated.
Robert N M Watson
Computer Laboratory
University of Cambridge
More information about the freebsd-fs
mailing list