Commits
Chris Wilson committed 0e6883b0437
drm/i915: Restore waitboost credit to the synchronous waiter Ideally, we want to automagically have the GPU respond to the instantaneous load by reclocking itself. However, reclocking occurs relatively slowly, and to the client waiting for a result from the GPU, too late. To compensate and reduce the client latency, we allow the first wait from a client to boost the GPU clocks to maximum. This overcomes the lag in autoreclocking, at the expense of forcing the GPU clocks too high. So to offset the excessive power usage, we currently allow a client to only boost the clocks once before we detect the GPU is idle again. This works reasonably for say the first frame in a benchmark, but for many more synchronous workloads (like OpenCL) we find the GPU clocks remain too low. By noting a wait which would idle the GPU (i.e. we just waited upon the last known request), we can give that client the idle boost credit (for their next wait) without the 100ms delay required for us to detect the GPU idle state. The intention is to boost clients that are stalling in the process of feeding the GPU more work (and who in doing so let the GPU idle), without granting boost credits to clients that are throttling themselves (such as compositors). Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: "Zou, Nanhai" <nanhai.zou@intel.com> Cc: Jesse Barnes <jbarnes@virtuousgeek.org> Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: http://patchwork.freedesktop.org/patch/msgid/1467616119-4093-4-git-send-email-chris@chris-wilson.co.uk