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

Timur Tabi
2005-04-25T23:13:21Z

Bob Woodruff wrote:

> There definitely needs to be a mechanism to prevent people from pinning
> too much memory.

Any limit would have to be very high - definitely more than just half. What if the
application needs to pin 2GB? The customer is not going to buy 4+ GB of RAM just because
Linux doesn't like pinning more than half. In an x86-32 system, that would required PAE
support and slow everything down.

Off the top of my head, I'd say Linux would need to allow all but 512MB to be pinned. So
you have 3GB of RAM, Linux should allow you to pin 2.5GB.

--
Timur Tabi
Staff Software Engineer
timur.tabi@ammasso.com

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