On Sat, Apr 02, 2011 at 07:46:31AM +0100, Chris Wilson wrote: > What I guess I was trying to express was that we need to be very clear > what the interface is for and the limitations about its use. > > For the more complicated set of registers, we can and should expose knobs > in the debugfs to read and write them. For instance, to control the render > clock frequencies and thresholds. > > But perhaps we do need to reconsider the performance aspect. intel_gpu_top > samples the ring HEAD and TAIL at around 10KHz and forcing gt-wake is > about 50 microseconds... I hope I'm mistaken, because even batched that is > doomed. Ben, do you mind checking that thought experiment with a little > hard fact?
Here is the data from ~100 samples while playing playing Armacycles Advanced measured off of d-i-f 7f58aabc369014fda3a4a33604ba0a1b63b941ac. min 02.775us max 19.402us avg 07.057us stddev 02.819us When I do a cat /sys/kernel/debug/dri/0/i915_gem_interrupt, I always get 3 reads, in a similar pattern to this: 6) ! 285.852 us | __gen6_gt_force_wake_get(); 6) 1.944 us | __gen6_gt_force_wake_get(); 6) 1.854 us | __gen6_gt_force_wake_get(); Not sure why that case is so different. > -Chris Ben _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
