Hi Tvrtko, > On Wed, Nov 7, 2018 at 4:08 PM Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx> wrote: > > > On 06/11/2018 04:13, Ankit Navik wrote: > > drm/i915: Context aware user agnostic EU/Slice/Sub-slice control > > within kernel > > > > Current GPU configuration code for i915 does not allow us to change > > EU/Slice/Sub-slice configuration dynamically. Its done only once while > > context is created. > > > > While particular graphics application is running, if we examine the > > command requests from user space, we observe that command density is not > consistent. > > It means there is scope to change the graphics configuration > > dynamically even while context is running actively. This patch series > > proposes the solution to find the active pending load for all active > > context at given time and based on that, dynamically perform graphics > configuration for each context. > > > > We use a hr (high resolution) timer with i915 driver in kernel to get > > a callback every few milliseconds (this timer value can be configured > > through debugfs, default is '0' indicating timer is in disabled state > > i.e. original system without any intervention).In the timer callback, > > we examine pending commands for a context in the queue, essentially, > > we intercept them before they are executed by GPU and we update context > with required number of EUs. > > > > Two questions, how did we arrive at right timer value? and what's the > > right number of EUs? For the prior one, empirical data to achieve best > > performance in least power was considered. For the later one, we > > roughly categorized number of EUs logically based on platform. Now we > > compare number of pending commands with a particular threshold and > > then set number of EUs accordingly with update context. That threshold > > is also based on experiments & findings. If GPU is able to catch up > > with CPU, typically there are no pending commands, the EU config would > > remain unchanged there. In case there are more pending commands we > > reprogram context with higher number of EUs. Please note, here we are > changing EUs even while context is running by examining pending commands > every 'x' > > milliseconds. > > > > With this solution in place, on KBL-GT3 + Android we saw following pnp > > benefits, power numbers mentioned here are system power. > > > > App /KPI | % Power | > > | Benefit | > > | (mW) | > > ---------------------------------| > > 3D Mark (Ice storm) | 2.30% | > > TRex On screen | 2.49% | > > TRex Off screen | 1.32% | > > ManhattanOn screen | 3.11% | > > Manhattan Off screen | 0.89% | > > AnTuTu 6.1.4 | 3.42% | > > Were you able to find some benchmarks which regress? Maybe try Synmark2 > and more from gfxbench? Not all benchmarks there are equally important, and > regressions on some are fine, but I think a fuller set would be interesting to see. We have not seen much improvement in GFX Carchase, but there was no degradation in performance. Regards, Ankit > > Regards, > > Tvrtko > > > > > Note - For KBL (GEN9) we cannot control at sub-slice level, it was > > always a constraint. > > We always controlled number of EUs rather than sub-slices/slices. > > > > Praveen Diwakar (4): > > drm/i915: Get active pending request for given context > > drm/i915: Update render power clock state configuration for given > > context > > drm/i915: set optimum eu/slice/sub-slice configuration based on load > > type > > drm/i915: Predictive governor to control eu/slice/subslice > > > > drivers/gpu/drm/i915/i915_debugfs.c | 88 > +++++++++++++++++++++++++++++- > > drivers/gpu/drm/i915/i915_drv.c | 1 + > > drivers/gpu/drm/i915/i915_drv.h | 10 ++++ > > drivers/gpu/drm/i915/i915_gem_context.c | 26 +++++++++ > > drivers/gpu/drm/i915/i915_gem_context.h | 45 +++++++++++++++ > > drivers/gpu/drm/i915/i915_gem_execbuffer.c | 5 ++ > > drivers/gpu/drm/i915/intel_device_info.c | 44 ++++++++++++++- > > drivers/gpu/drm/i915/intel_lrc.c | 20 ++++++- > > 8 files changed, 235 insertions(+), 4 deletions(-) > > _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
