Correct. This is what I was referring to when I said hardware support would be needed to make use of the 2.6.27 page mapping callback notifications. I don't know of any current HCAs which support this sort of dynamic mapping.
On Wed, 2009-04-29 at 13:16 -0700, Ted H. Kim wrote: > Unless you went the whole way of not really pinning > and allowing paging of registered memory. > Of course before anything got paged out, you would have > to call the HCA driver to mark said pages "not present". > And if you hit such pages when processing a work > request in the HCA, you would have to take a page fault, > get the page back and resume the work request > (and probably hold off the remote side with an RNR_NAK > in the meantime). > > This was a lively topic of conversation a long time ago > in IBTA ... and probably a bigger patch to the world > than people were contemplating :-). > > -ted > > > > This would be nice except that it is impossible. > > The whole idea behind virtual memory is that the application uses > > virtual addresses which are only temporarily mapped to physical > > memory by the OS. If the OS allowed a user to lock the > > virtual to physical mapping for all of physical memory, the OS > > wouldn't be able to run any other processes, do I/O, etc. > > The process can have a larger virtual address space than the > > available physical memory so no fixed mapping is possible. > > To prevent this, the application has limits imposed by the OS > > (type "ulimit -l"). > _______________________________________________ general mailing list [email protected] http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
