Andy Isaacson wrote:
If you take the hardline position that "the app is the only thing that matters", your code is unlikely to get merged. Linux is a general-purpose OS.
The problem is that our driver and library implement an API that we don't fully control. The API states that the application allocates the memory and tells the library to register it. The app then goes on its merry way until it's done, at which point it tells the library to deregister the memory. Neither the app nor the API has any provision for the app to be notified that the memory is no longer pinned and therefore can't be trusted. That would be considered a critical failure from the app's perspective, so the kernel would be doing it a favor by killing the process.
You might want to consider what happens with your communication system in a machine running power-saving modes (in the limit, suspend-to-disk). Of course most machines with Infiniband adapters aren't running swsusp, but it's not inconceivable that blade servers might sleep to lower power and cooling costs.
Any application that registers memory, will in all likelihood be running at 100% CPU non-stop. The computer is not going to be doing anything else but whatever that app is trying to do. The application could conceiveable register gigabytes of RAM, and if even a single page becomes unpinned, the whole thing is worthless. The application cannot do anything meaningful if it gets a message saying that some of the memory has become unpinned and should not be used.
So the real question is: how important is it to the kernel developers that Linux support these kinds of enterprise-class applications?
-- Timur Tabi Staff Software Engineer [EMAIL PROTECTED]
One thing a Southern boy will never say is, "I don't think duct tape will fix it." -- Ed Smylie, NASA engineer for Apollo 13 _______________________________________________ openib-general mailing list openib-general@openib.org http://openib.org/mailman/listinfo/openib-general
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