On Thu, Oct 23, 2014 at 04:03:56PM +0530, akash.goel@xxxxxxxxx wrote: > From: Akash Goel <akash.goel@xxxxxxxxx> > > This is for improving the CPU write operation performance, as with such > mapping, writes are almost 50% faster than with mmap_gtt. Also it avoids the I doubt it is the actual write that is faster. For example, gtt wc Operation -------- ------ --------- 424000.0 1.30 ShmPutImage 10x10 square 29500.0 1.42 ShmPutImage 100x100 square 1510.0 0.95 ShmPutImage 500x500 square It seems to reduce the overhead for small transfers (with an already mmaped pointer). That's interesting certainly, and probably a Clue for further improving performance. But it looks like peak throughput is limited by memory bandwidth, which has been my experience with the GTT mmap thus far. I have some doubts as to whether it is coherent with the display though, and so whether it is truly write-combining... -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
