[openib-general] kernel VM monitor for memory registration caching

[Pete Wyckoff]

Following up on the thread "Question about pinning memory" of last
week or so, I cleaned up the test implementation of the mechanism
I presented and put it on the web for download:

    http://www.osc.edu/~pw/dreg/

This is not meant for submission to openib or to the linux kernel.
It is just a prototype to show that the basic idea should work.

Here's the description from the web page:

    This kernel module and userspace library together implement a
    virtual memory (VM) monitoring system for the linux kernel.
    When communication libraries, such as MPI or PVFS2, support
    network devices that require memory registration, such as
    Infiniband, the libraries tend to register user memory
    dynamically and cache those registrations hoping to later reuse
    them.  Unfortunately, the user application can unmap the memory,
    through a call to free() or explicit munmap(), for example, and
    the communication library never finds out.  With this work, the
    kernel module notices the VM activity and notifies the userspace
    communication library of what happened.

I'll be happy to discuss the code with anyone who ends up wanting
to use it or improve upon it.

		-- Pete