drm/i915: Only apply the jump to the "efficient RPS" frequency on startup

Currently we apply the jump to rpe if we are below it and the GPU needs
more power. For some GPUs, the rpe is 75% of the maximum range causing
us to dramatically overshoot low power applications *and* unable to
reach the low frequency that can most efficiently deliver their
workload.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170210150348.22146-3-chris@chris-wilson.co.uk
Reviewed-by: Radoslaw Szwichtenberg <radoslaw.szwichtenberg@intel.com>

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 86cca37a4e4f38dba167b47f0f8b471ff7663d2d..84fda3fce4b84d62e3e56b198089f7936fd3ec02 100644 (file)
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1173,14 +1173,6 @@ static void gen6_pm_rps_work(struct work_struct *work)
 
                if (new_delay >= dev_priv->rps.max_freq_softlimit)
                        adj = 0;
-               /*
-                * For better performance, jump directly
-                * to RPe if we're below it.
-                */
-               if (new_delay < dev_priv->rps.efficient_freq - adj) {
-                       new_delay = dev_priv->rps.efficient_freq;
-                       adj = 0;
-               }
        } else if (client_boost || any_waiters(dev_priv)) {
                adj = 0;
        } else if (pm_iir & GEN6_PM_RP_DOWN_TIMEOUT) {

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index e801b5d26b90fe2a8e5fa87ff621513b6edee15a..3d311e10064306063eec10e60303f8cc4e9793ab 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5019,6 +5019,8 @@ void gen6_rps_busy(struct drm_i915_private *dev_priv)
 {
        mutex_lock(&dev_priv->rps.hw_lock);
        if (dev_priv->rps.enabled) {
+               u8 freq;
+
                if (dev_priv->pm_rps_events & (GEN6_PM_RP_DOWN_EI_EXPIRED | GEN6_PM_RP_UP_EI_EXPIRED))
                        gen6_rps_reset_ei(dev_priv);
                I915_WRITE(GEN6_PMINTRMSK,
@@ -5026,9 +5028,14 @@ void gen6_rps_busy(struct drm_i915_private *dev_priv)
 
                gen6_enable_rps_interrupts(dev_priv);
 
-               /* Ensure we start at the user's desired frequency */
+               /* Use the user's desired frequency as a guide, but for better
+                * performance, jump directly to RPe as our starting frequency.
+                */
+               freq = max(dev_priv->rps.cur_freq,
+                          dev_priv->rps.efficient_freq);
+
                if (intel_set_rps(dev_priv,
-                                 clamp(dev_priv->rps.cur_freq,
+                                 clamp(freq,
                                        dev_priv->rps.min_freq_softlimit,
                                        dev_priv->rps.max_freq_softlimit)))
                        DRM_DEBUG_DRIVER("Failed to set idle frequency\n");