Subject: Re: [PATCH 3/3] powerpc: POWER7 optimised copy_to_user/copy_from_user using VMX

From: Benjamin Herrenschmidt <[email-masked]>
Date: Fri, 17 Jun 2011 15:58:20 +1000

On Fri, 2011-06-17 at 14:54 +1000, Anton Blanchard wrote:
> plain text document attachment (power7_copy_tofrom_user)
> Implement a POWER7 optimised copy_to_user/copy_from_user using VMX.
> For large aligned copies this new loop is over 10% faster, and for
> large unaligned copies it is over 200% faster.
> 
> If we take a fault we fall back to the old version, this keeps
> things relatively simple and easy to verify.

Same re-entrancy comment as the other ones. preempt & interrupts...
Except here is worse since you may page fault and thus lose the vmx
state completely.

Cheers,
Ben.