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

Andrew Morton
2005-04-26T00:13:15Z

Roland Dreier <roland@topspin.com> wrote:
>
> Andrew> ug. What stops the memory from leaking if the process
> Andrew> exits?
>
> Andrew> I hope this is a privileged operation?
>
> I don't think it has to be privileged. In my implementation, the
> driver keeps a per-process list of registered memory regions and
> unpins/cleans up on process exit.

How does the driver detect process exit?

> Andrew> It would be better to obtain this memory via a mmap() of
> Andrew> some special device node, so we can perform appropriate
> Andrew> permission checking and clean everything up on unclean
> Andrew> application exit.
>
> This seems to interact poorly with how applications want to use RDMA,
> ie typically through a library interface such as MPI. People doing
> HPC don't want to recode their apps to use a new allocator, they just
> want to link to a new MPI library and have the app go fast.

Fair enough.