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

From: Roland Dreier
Date: Mon Apr 25 2005 - 18:59:32 EST

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.

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.

- R.

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