drm/i915: Use spinlocks for checking when to waitboost
In commit 1854d5ca0dd7a9fc11243ff220a3e93fce2b4d3e
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue Apr 7 16:20:32 2015 +0100
drm/i915: Deminish contribution of wait-boosting from clients
we removed an atomic timer based check for allowing waitboosting and
moved it below the mutex taken during RPS. However, that mutex can be
held for long periods of time on Vallyview/Cherryview as communication
with the PCU is slow. As clients may frequently wait for results (e.g.
such as tranform feedback) we introduced contention between the client
and the RPS worker. We can take advantage of the RPS worker, by
switching the wait boost decision to use spin locks and defer the
actual reclocking to the worker.
Fixes a regression of up to 45% on Baytrail and Baswell!
v2 (Daniel):
- Use max_freq_softlimit instead of the not-yet-merged boost
frequency.
- Don't inject a fake irq into the boost work, instead treat
client_boost as just another legit waker.
v3: Drop the now unused mask (Chris).
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90112
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> (v1)
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 9adfd12..3f6cad9 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1089,9 +1089,12 @@
int last_adj;
enum { LOW_POWER, BETWEEN, HIGH_POWER } power;
+ spinlock_t client_lock;
+ struct list_head clients;
+ bool client_boost;
+
bool enabled;
struct delayed_work delayed_resume_work;
- struct list_head clients;
unsigned boosts;
struct intel_rps_client semaphores, mmioflips;
@@ -1101,7 +1104,9 @@
/*
* Protects RPS/RC6 register access and PCU communication.
- * Must be taken after struct_mutex if nested.
+ * Must be taken after struct_mutex if nested. Note that
+ * this lock may be held for long periods of time when
+ * talking to hw - so only take it when talking to hw!
*/
struct mutex hw_lock;
};