Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation

Christoph Hellwig
2005-04-26T06:13:06Z

On Mon, Apr 25, 2005 at 05:02:36PM -0700, Roland Dreier wrote:
> The idea is that applications manage the lifetime of pinned memory
> regions. They can do things like post multiple I/O operations without
> any page-walking overhead, or pass a buffer descriptor to a remote
> host who will send data at some indeterminate time in the future. In
> addition, InfiniBand has the notion of atomic operations, so a cluster
> application may be using some memory region to implement a global lock.
>
> This might not be the most kernel-friendly design but it is pretty
> deeply ingrained in the design of RDMA transports like InfiniBand and
> iWARP (RDMA over IP).

Actuallky, no it isn't. All these transports would work just fine with
the mmap a character device to hand out memory from the kernel approach
I told you to use multiple times and Andrew mentioned in this thread aswell.
What doesn't work with that design are the braindead designed by comittee
APIs in the RDMA world - but I don't think we should care about them too
much.