Re: [openib-general] Re: [PATCH][RFC][0/4] InfiniBand userspace verbsimplementation

From: Timur Tabi
Date: Tue Apr 26 2005 - 15:24:26 EST

Roland Dreier wrote:

Yes, I agree. If an app wants to register half a page and pass the
other half to a child process, I think the only answer is "don't do
that then."

How can the app know that, though? It would have to allocate I/O buffers with knowledge of page boundaries. Today, the apps just malloc() a bunch of memory and pay no attention to whether the beginning or the end of the buffer shares a page with some other, unrelated object. We may as well tell the app that it needs to page-align all I/O buffers.

My point is that we can't just simply say, "Don't do that". Some entity (the kernel, libraries, whatever) should be able to tell the app that its usage of memory is going to break in some unpredictable way.

Timur Tabi
Staff Software Engineer

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
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