At 02:44 PM 9/30/2008, J. Bruce Fields wrote: >On Mon, Sep 29, 2008 at 10:07:25PM -0500, Tom Tucker wrote: >> What's your perspective on the lifetime of bounce buffers, memory >> windows, and the other strategies in client? > >I'm ignorant. Pointer to something else I should read? > >I assume there are similar issues on the client? Tom's asking about the client memory registration options and whether they should all remain in the client code going forward. There are different strategies in there, depending on what the hardware supports, how well it supports it, and how you want to run it all. The multiple strategies stem from the early days when no two adapters did quite the same thing. That said, at least one of them is no longer useful - no adapters support windows today, since the demise of Ammasso, although the kernel API to drive them is still there in the OFA stack below. I think it's possible that some of the other modes can collapse, but not just now. There's a lot of older hardware out there, and newer hardware may appear to use the old stuff too. Another concern I have, frankly, is interoperability. If we collapse the modes, then the temptation to assume both ends have such- and-such a capability increase. If one side tries some RDMA operation that is only supported properly by a certain adapter, it's hard to detect that in a monoculture. Having the option to switch modes can help avert this, by testing for it. In any case, if the current code doesn't work, it's a bug. Certainly bouncebuffers (non-RDMA mode) should work perfectly and I plan to check it asap. Tom. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
