On Tue, Feb 04, 2014 at 01:30:19PM +0000, Chris Wilson wrote: > Inserting additional PTEs has no side-effect for us as the pfn are fixed > for the entire time the object is resident in the global GTT. The > downside is that we pay the entire cost of faulting the object upon the > first hit, for which we in return receive the benefit of removing the > per-page faulting overhead. > > On an Ivybridge i7-3720qm with 1600MHz DDR3, with 32 fences, > Upload rate for 2 linear surfaces: 8127MiB/s -> 8134MiB/s > Upload rate for 2 tiled surfaces: 8607MiB/s -> 8625MiB/s > Upload rate for 4 linear surfaces: 8127MiB/s -> 8127MiB/s > Upload rate for 4 tiled surfaces: 8611MiB/s -> 8602MiB/s > Upload rate for 8 linear surfaces: 8114MiB/s -> 8124MiB/s > Upload rate for 8 tiled surfaces: 8601MiB/s -> 8603MiB/s > Upload rate for 16 linear surfaces: 8110MiB/s -> 8123MiB/s > Upload rate for 16 tiled surfaces: 8595MiB/s -> 8606MiB/s > Upload rate for 32 linear surfaces: 8104MiB/s -> 8121MiB/s > Upload rate for 32 tiled surfaces: 8589MiB/s -> 8605MiB/s > Upload rate for 64 linear surfaces: 8107MiB/s -> 8121MiB/s > Upload rate for 64 tiled surfaces: 2013MiB/s -> 3017MiB/s > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Cc: "Goel, Akash" <akash.goel@xxxxxxxxx> > --- > > It survived light testing without noticable performance degradation. Can > anyone think of how this will impact us negatively? piglit does an awful lot of single-pixel readbacks iirc, that's about the only thing I could think of. Maybe we should wait until we have the vm_insert_pfn_frm_io_mapping to not adversely affect this. Or if the overhead is negligible we could move ahead right away. Nothing else really crosses my mind which would qualify as real-world usage. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
