drm/i915: Introduce DRM_I915_THROTTLE_JIFFIES
As Daniel commented on
commit b7ffe1362c5f468b853223acc9268804aa92afc8
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon Apr 27 13:41:24 2015 +0100
drm/i915: Free RPS boosts for all laggards
it is better to be explicit when sharing hardcoded values such as
throttle/boost timeouts. Make it so!
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 44d592f..1038f5c 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -279,6 +279,12 @@
struct {
spinlock_t lock;
struct list_head request_list;
+/* 20ms is a fairly arbitrary limit (greater than the average frame time)
+ * chosen to prevent the CPU getting more than a frame ahead of the GPU
+ * (when using lax throttling for the frontbuffer). We also use it to
+ * offer free GPU waitboosts for severely congested workloads.
+ */
+#define DRM_I915_THROTTLE_JIFFIES msecs_to_jiffies(20)
} mm;
struct idr context_idr;