[Intel-gfx] [RFC][PATCH] drm/i915 Prefetch data from memory

[Ben Gamari]

On Wed, Jul 22, 2009 at 06:59:42PM -0700, Eric Anholt wrote:
> On Tue, 2009-07-21 at 14:18 +0800, ling.ma at intel.com wrote:
> > We read data from memory(WB type), in most cases we need not 
> > care about prefetch because hardware data prefetch is good enough.
> > However here our gpu address is not continuous, hardware prefetch
> > is not effective, so we intends to prefetch data in advance.
> 
> Can you include measurement of the impact in the commit message?
> 
> Also, what if you prefetch past the end of the buffer?
If I recall correctly, the prefetch instruction has no effect if one
accesses an invalid address. The CPU knows that the instruction is just
a hint and will continue on its merry way.