On Sat, Jan 8, 2011 at 2:07 AM, Chris Wilson chris@chris-wilson.co.uk wrote:
I've been looking at how we can improve upload/download performance on our UMA gfx. One under-used aspect of the IGP is its ability to blit between snooped-and-unsnooped memory i.e. from normal ram into the GTT. Only the BLT has this ability, almost all other functions of the GPU most be from unsnooped memory. SNB introduces its own cache handling that we need to exploit further, however the BLT remains and is orders of magnitude faster for read back than an UC read by the CPU...
You might want to test this on a 945G era machine, I think I tried to get this working back in the TTM days, I got a lot of crashes and pain and suffering.
But I might have had bad ops happening occasionally or something.
Dave.