drm/i915: Group the irq breadcrumb variables into the same cacheline

As we inspect both the tasklet (to check for an active bottom-half) and
set the irq-posted flag at the same time (both in the interrupt handler
and then in the bottom-halt), group those two together into the same
cacheline. (Not having total control over placement of the struct means
we can't guarantee the cacheline boundary, we need to align the kmalloc
and then each struct, but the grouping should help.)

v2: Try a couple of different names for the state touched by the user
interrupt handler.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467805142-22219-3-git-send-email-chris@chris-wilson.co.uk

1 files changed, 10 insertions, 8 deletions

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 121294c..12cb7ed 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -74,8 +74,8 @@ enum intel_ring_hangcheck_action {
 
 struct intel_ring_hangcheck {
 	u64 acthd;
+	unsigned long user_interrupts;
 	u32 seqno;
-	unsigned user_interrupts;
 	int score;
 	enum intel_ring_hangcheck_action action;
 	int deadlock;
@@ -167,16 +167,20 @@ struct intel_engine_cs {
 	 * the overhead of waking that client is much preferred.
 	 */
 	struct intel_breadcrumbs {
+		struct task_struct *irq_seqno_bh; /* bh for user interrupts */
+		unsigned long irq_wakeups;
+		bool irq_posted;
+
 		spinlock_t lock; /* protects the lists of requests */
 		struct rb_root waiters; /* sorted by retirement, priority */
 		struct rb_root signals; /* sorted by retirement */
 		struct intel_wait *first_wait; /* oldest waiter by retirement */
-		struct task_struct *tasklet; /* bh for user interrupts */
 		struct task_struct *signaler; /* used for fence signalling */
 		struct drm_i915_gem_request *first_signal;
 		struct timer_list fake_irq; /* used after a missed interrupt */
-		bool irq_enabled;
-		bool rpm_wakelock;
+
+		bool irq_enabled : 1;
+		bool rpm_wakelock : 1;
 	} breadcrumbs;
 
 	/*
@@ -189,7 +193,6 @@ struct intel_engine_cs {
 	struct intel_hw_status_page status_page;
 	struct i915_ctx_workarounds wa_ctx;
 
-	bool		irq_posted;
 	u32             irq_keep_mask; /* always keep these interrupts */
 	u32		irq_enable_mask; /* bitmask to enable ring interrupt */
 	void		(*irq_enable)(struct intel_engine_cs *ring);
@@ -319,7 +322,6 @@ struct intel_engine_cs {
 	 * inspecting request list.
 	 */
 	u32 last_submitted_seqno;
-	unsigned user_interrupts;
 
 	bool gpu_caches_dirty;
 
@@ -543,13 +545,13 @@ void intel_engine_enable_signaling(struct drm_i915_gem_request *request);
 
 static inline bool intel_engine_has_waiter(struct intel_engine_cs *engine)
 {
-	return READ_ONCE(engine->breadcrumbs.tasklet);
+	return READ_ONCE(engine->breadcrumbs.irq_seqno_bh);
 }
 
 static inline bool intel_engine_wakeup(struct intel_engine_cs *engine)
 {
 	bool wakeup = false;
-	struct task_struct *tsk = READ_ONCE(engine->breadcrumbs.tasklet);
+	struct task_struct *tsk = READ_ONCE(engine->breadcrumbs.irq_seqno_bh);
 	/* Note that for this not to dangerously chase a dangling pointer,
 	 * the caller is responsible for ensure that the task remain valid for
 	 * wake_up_process() i.e. that the RCU grace period cannot expire.