[Lustre-devel] Queries regarding LDLM_ENQUEUE
Nicolas Williams
Nicolas.Williams at oracle.com
Wed Oct 20 07:55:57 PDT 2010
On Wed, Oct 20, 2010 at 10:51:06AM -0400, Paul Nowoczynski wrote:
> Eric makes a good point in that only parallel jobs really need this
> feature. Unfortunately, at scale the system (both clients and servers)
> *really do* need something like this, especially if we continue pushing
> users to perform N-1 file I/O instead of 'file per process'. I too am in
> agreement that some sort of capability mechanism is the best approach. I
> wonder if this is something that could be done outside of POSIX and
> supported through a parallel I/O library? Perhaps a single application
> threads could make a special open call (/proc magic perhaps?) and obtain
> the glob of opaque bytes which are then broadcast to the rest of the
> client via mpi. Traversing the namespace would be avoided on all but one
> client. In such a scenario I don't feel that enforcing unix permissions
> at every level of the path is needed or sensible, the operation should
> be treated as a simple logical open. The question to the lustre experts
> - can enough state be packed into an opaque object such that the
> recv'ing client can construct the necessary cache state?
POSIX already has what you're asking for, and it's called openg() ;)
More information about the lustre-devel
mailing list