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

[Andrew Morton]

Timur Tabi <timur.tabi at ammasso.com> wrote:
>
> 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.
> 

You can pin the whole darn lot *if you have the correct privileges*.