[openib-general] single rkey

[Caitlin Bestler]

On 8/31/06, yipee <yipeeyipeeyipeeyipee at yahoo.com> wrote:
> Hi,
>
> Is it possible for several memory registrations (using ibv_reg_mr) to have a
> single rkey?
> Can I add memory registrations to a previous rkey?
>
>

You need to create the Memory Region as large as you think it will
need to be. But there are two things you can keep in mind:

1) You can create multiple Memory Regions. A scatter gather list
    can reference multiple memory regions.
2) You can create Memory Windows within Memory Regions to
    limit the scope exposed to the remote end.
3) The same pages can be registered to multiple Memory Regions.
    So you could create a *new* Memory Region that included the
    prior pages *and* the new pages, use that, and release the old
    Memory Region eventually when all use of it ended.

The goal of making Memory Region lookups by hardware efficient
has encouraged most implementations to use data structures
that are not friendly for dynamic host manipulation while the
Memory Region is already in use. That's why the API is designed
to set the contents of a Memory Region in a single operation
rather than by piecemeal addition.