[Bug 102336] [BYT] Offscreen tests performance drops to <1/3 due to power management

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=102336

--- Comment #1 from Chris Wilson <chris at chris-wilson.co.uk> ---
Maxing out the GPU (at least GAM) results in 50% c0 activity. I'm guessing out
cdlck is incorrect, or slightly different to the c0 cycles:

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 32c62442c9d8..4b36ed2290b9 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1076,7 +1076,7 @@ static u32 vlv_wa_c0_ei(struct drm_i915_private
*dev_priv, u32 pm_iir)

                time = ktime_us_delta(now.ktime, prev->ktime);

-               time *= dev_priv->czclk_freq;
+               time *= dev_priv->czclk_freq / 2;

                /* Workload can be split between render + media,
                 * e.g. SwapBuffers being blitted in X after being rendered in

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