Jeff Squyres wrote:
WHAT: make mpi_leave_pinned=1 by default when a BTL is used that would
benefit from it (when possible; 0 when not, obviously)
Comments?
The probable reason registration cache (aka leave_pinned) is disabled by
default is that it may be unsafe. Even if you use mallocopt to never
return memory to the OS, how do you guarantee that:
* malloc always enforce the mallocopt *hints*.
* pinned memory can safely be fork()ed (system() for example).
* pinned memory can safely be unmmap()ed (Direct I/O or file mapping for
example).
If you can't, one solution may be to write a simple MPI code that
corrupts MVAPICH and make some noise about it.
My 2 cents.
Patrick
