drm/i915: Make request allocation caches global

As kmem_caches share the same properties (size, allocation/free behaviour)
for all potential devices, we can use global caches. While this
potential has worse fragmentation behaviour (one can argue that
different devices would have different activity lifetimes, but you can
also argue that activity is temporal across the system) it is the
default behaviour of the system at large to amalgamate matching caches.

The benefit for us is much reduced pointer dancing along the frequent
allocation paths.

v2: Defer shrinking until after a global grace period for futureproofing
multiple consumers of the slab caches, similar to the current strategy
for avoiding shrinking too early.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190228102035.5857-1-chris@chris-wilson.co.uk

4 files changed, 26 insertions, 64 deletions

diff --git a/drivers/gpu/drm/i915/selftests/mock_engine.c b/drivers/gpu/drm/i915/selftests/mock_engine.c
index 6f3fb803c747..ec1ae948954c 100644
--- a/drivers/gpu/drm/i915/selftests/mock_engine.c
+++ b/drivers/gpu/drm/i915/selftests/mock_engine.c
@@ -76,26 +76,26 @@ static void mock_ring_free(struct intel_ring *base)
 	kfree(ring);
 }
 
-static struct mock_request *first_request(struct mock_engine *engine)
+static struct i915_request *first_request(struct mock_engine *engine)
 {
 	return list_first_entry_or_null(&engine->hw_queue,
-					struct mock_request,
-					link);
+					struct i915_request,
+					mock.link);
 }
 
-static void advance(struct mock_request *request)
+static void advance(struct i915_request *request)
 {
-	list_del_init(&request->link);
-	i915_request_mark_complete(&request->base);
-	GEM_BUG_ON(!i915_request_completed(&request->base));
+	list_del_init(&request->mock.link);
+	i915_request_mark_complete(request);
+	GEM_BUG_ON(!i915_request_completed(request));
 
-	intel_engine_queue_breadcrumbs(request->base.engine);
+	intel_engine_queue_breadcrumbs(request->engine);
 }
 
 static void hw_delay_complete(struct timer_list *t)
 {
 	struct mock_engine *engine = from_timer(engine, t, hw_delay);
-	struct mock_request *request;
+	struct i915_request *request;
 	unsigned long flags;
 
 	spin_lock_irqsave(&engine->hw_lock, flags);
@@ -110,8 +110,9 @@ static void hw_delay_complete(struct timer_list *t)
 	 * requeue the timer for the next delayed request.
 	 */
 	while ((request = first_request(engine))) {
-		if (request->delay) {
-			mod_timer(&engine->hw_delay, jiffies + request->delay);
+		if (request->mock.delay) {
+			mod_timer(&engine->hw_delay,
+				  jiffies + request->mock.delay);
 			break;
 		}
 
@@ -169,10 +170,8 @@ err:
 
 static int mock_request_alloc(struct i915_request *request)
 {
-	struct mock_request *mock = container_of(request, typeof(*mock), base);
-
-	INIT_LIST_HEAD(&mock->link);
-	mock->delay = 0;
+	INIT_LIST_HEAD(&request->mock.link);
+	request->mock.delay = 0;
 
 	return 0;
 }
@@ -190,7 +189,6 @@ static u32 *mock_emit_breadcrumb(struct i915_request *request, u32 *cs)
 
 static void mock_submit_request(struct i915_request *request)
 {
-	struct mock_request *mock = container_of(request, typeof(*mock), base);
 	struct mock_engine *engine =
 		container_of(request->engine, typeof(*engine), base);
 	unsigned long flags;
@@ -198,12 +196,13 @@ static void mock_submit_request(struct i915_request *request)
 	i915_request_submit(request);
 
 	spin_lock_irqsave(&engine->hw_lock, flags);
-	list_add_tail(&mock->link, &engine->hw_queue);
-	if (mock->link.prev == &engine->hw_queue) {
-		if (mock->delay)
-			mod_timer(&engine->hw_delay, jiffies + mock->delay);
+	list_add_tail(&request->mock.link, &engine->hw_queue);
+	if (list_is_first(&request->mock.link, &engine->hw_queue)) {
+		if (request->mock.delay)
+			mod_timer(&engine->hw_delay,
+				  jiffies + request->mock.delay);
 		else
-			advance(mock);
+			advance(request);
 	}
 	spin_unlock_irqrestore(&engine->hw_lock, flags);
 }
@@ -263,12 +262,12 @@ void mock_engine_flush(struct intel_engine_cs *engine)
 {
 	struct mock_engine *mock =
 		container_of(engine, typeof(*mock), base);
-	struct mock_request *request, *rn;
+	struct i915_request *request, *rn;
 
 	del_timer_sync(&mock->hw_delay);
 
 	spin_lock_irq(&mock->hw_lock);
-	list_for_each_entry_safe(request, rn, &mock->hw_queue, link)
+	list_for_each_entry_safe(request, rn, &mock->hw_queue, mock.link)
 		advance(request);
 	spin_unlock_irq(&mock->hw_lock);
 }
diff --git a/drivers/gpu/drm/i915/selftests/mock_gem_device.c b/drivers/gpu/drm/i915/selftests/mock_gem_device.c
index fc516a2970f4..5a98caba6d69 100644
--- a/drivers/gpu/drm/i915/selftests/mock_gem_device.c
+++ b/drivers/gpu/drm/i915/selftests/mock_gem_device.c
@@ -79,9 +79,6 @@ static void mock_device_release(struct drm_device *dev)
 
 	destroy_workqueue(i915->wq);
 
-	kmem_cache_destroy(i915->priorities);
-	kmem_cache_destroy(i915->dependencies);
-	kmem_cache_destroy(i915->requests);
 	kmem_cache_destroy(i915->vmas);
 	kmem_cache_destroy(i915->objects);
 
@@ -211,23 +208,6 @@ struct drm_i915_private *mock_gem_device(void)
 	if (!i915->vmas)
 		goto err_objects;
 
-	i915->requests = KMEM_CACHE(mock_request,
-				    SLAB_HWCACHE_ALIGN |
-				    SLAB_RECLAIM_ACCOUNT |
-				    SLAB_TYPESAFE_BY_RCU);
-	if (!i915->requests)
-		goto err_vmas;
-
-	i915->dependencies = KMEM_CACHE(i915_dependency,
-					SLAB_HWCACHE_ALIGN |
-					SLAB_RECLAIM_ACCOUNT);
-	if (!i915->dependencies)
-		goto err_requests;
-
-	i915->priorities = KMEM_CACHE(i915_priolist, SLAB_HWCACHE_ALIGN);
-	if (!i915->priorities)
-		goto err_dependencies;
-
 	i915_timelines_init(i915);
 
 	INIT_LIST_HEAD(&i915->gt.active_rings);
@@ -257,12 +237,6 @@ err_context:
 err_unlock:
 	mutex_unlock(&i915->drm.struct_mutex);
 	i915_timelines_fini(i915);
-	kmem_cache_destroy(i915->priorities);
-err_dependencies:
-	kmem_cache_destroy(i915->dependencies);
-err_requests:
-	kmem_cache_destroy(i915->requests);
-err_vmas:
 	kmem_cache_destroy(i915->vmas);
 err_objects:
 	kmem_cache_destroy(i915->objects);
diff --git a/drivers/gpu/drm/i915/selftests/mock_request.c b/drivers/gpu/drm/i915/selftests/mock_request.c
index 0dc29e242597..d1a7c9608712 100644
--- a/drivers/gpu/drm/i915/selftests/mock_request.c
+++ b/drivers/gpu/drm/i915/selftests/mock_request.c
@@ -31,29 +31,25 @@ mock_request(struct intel_engine_cs *engine,
 	     unsigned long delay)
 {
 	struct i915_request *request;
-	struct mock_request *mock;
 
 	/* NB the i915->requests slab cache is enlarged to fit mock_request */
 	request = i915_request_alloc(engine, context);
 	if (IS_ERR(request))
 		return NULL;
 
-	mock = container_of(request, typeof(*mock), base);
-	mock->delay = delay;
-
-	return &mock->base;
+	request->mock.delay = delay;
+	return request;
 }
 
 bool mock_cancel_request(struct i915_request *request)
 {
-	struct mock_request *mock = container_of(request, typeof(*mock), base);
 	struct mock_engine *engine =
 		container_of(request->engine, typeof(*engine), base);
 	bool was_queued;
 
 	spin_lock_irq(&engine->hw_lock);
-	was_queued = !list_empty(&mock->link);
-	list_del_init(&mock->link);
+	was_queued = !list_empty(&request->mock.link);
+	list_del_init(&request->mock.link);
 	spin_unlock_irq(&engine->hw_lock);
 
 	if (was_queued)
diff --git a/drivers/gpu/drm/i915/selftests/mock_request.h b/drivers/gpu/drm/i915/selftests/mock_request.h
index 995fb728380c..4acf0211df20 100644
--- a/drivers/gpu/drm/i915/selftests/mock_request.h
+++ b/drivers/gpu/drm/i915/selftests/mock_request.h
@@ -29,13 +29,6 @@
 
 #include "../i915_request.h"
 
-struct mock_request {
-	struct i915_request base;
-
-	struct list_head link;
-	unsigned long delay;
-};
-
 struct i915_request *
 mock_request(struct intel_engine_cs *engine,
 	     struct i915_gem_context *context,