diff mbox series

[7/7] drm/syncobj: Add a fast path to drm_syncobj_array_find

Message ID 20250106105521.53149-8-tursulin@igalia.com (mailing list archive)
State New
Headers show
Series A few drm_syncobj optimisations | expand

Commit Message

Tvrtko Ursulin Jan. 6, 2025, 10:55 a.m. UTC 
From: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>

Running the Cyberpunk 2077 benchmark we can observe that the lookup helper
is relatively hot, but the 97% of the calls are for a single object. (~3%
for two points, and never more than three points. While a more trivial
workload like vkmark under Plasma is even more skewed to single point
lookups.)

Therefore lets add a fast path to bypass the kmalloc_array/kfree and use a
pre-allocated stack array for those cases.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
---
 drivers/gpu/drm/drm_syncobj.c | 53 +++++++++++++++++++++++++++--------
 1 file changed, 41 insertions(+), 12 deletions(-)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 94932b89298f..233bdef53c87 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -1223,6 +1223,8 @@  EXPORT_SYMBOL(drm_timeout_abs_to_jiffies);
 static int drm_syncobj_array_find(struct drm_file *file_private,
 				  u32 __user *handles,
 				  uint32_t count,
+				  struct drm_syncobj **stack_syncobjs,
+				  u32 stack_count,
 				  struct drm_syncobj ***syncobjs_out)
 {
 	struct drm_syncobj **syncobjs;
@@ -1232,9 +1234,13 @@  static int drm_syncobj_array_find(struct drm_file *file_private,
 	if (!access_ok(handles, count * sizeof(*handles)))
 		return -EFAULT;
 
-	syncobjs = kmalloc_array(count, sizeof(*syncobjs), GFP_KERNEL);
-	if (!syncobjs)
-		return -ENOMEM;
+	if (count > stack_count) {
+		syncobjs = kmalloc_array(count, sizeof(*syncobjs), GFP_KERNEL);
+		if (!syncobjs)
+			return -ENOMEM;
+	} else {
+		syncobjs = stack_syncobjs;
+	}
 
 	for (i = 0; i < count; i++) {
 		u64 handle;
@@ -1260,25 +1266,31 @@  static int drm_syncobj_array_find(struct drm_file *file_private,
 			drm_syncobj_put(syncobjs[i]);
 		i--;
 	}
-	kfree(syncobjs);
+
+	if (syncobjs != stack_syncobjs)
+		kfree(syncobjs);
 
 	return ret;
 }
 
 static void drm_syncobj_array_free(struct drm_syncobj **syncobjs,
-				   uint32_t count)
+				   uint32_t count,
+				   struct drm_syncobj **stack_syncobjs)
 {
 	uint32_t i;
 
 	for (i = 0; i < count; i++)
 		drm_syncobj_put(syncobjs[i]);
-	kfree(syncobjs);
+
+	if (syncobjs != stack_syncobjs)
+		kfree(syncobjs);
 }
 
 int
 drm_syncobj_wait_ioctl(struct drm_device *dev, void *data,
 		       struct drm_file *file_private)
 {
+	struct drm_syncobj *stack_syncobjs[4];
 	struct drm_syncobj_wait *args = data;
 	ktime_t deadline, *pdeadline = NULL;
 	u32 count = args->count_handles;
@@ -1304,6 +1316,8 @@  drm_syncobj_wait_ioctl(struct drm_device *dev, void *data,
 	ret = drm_syncobj_array_find(file_private,
 				     u64_to_user_ptr(args->handles),
 				     count,
+				     stack_syncobjs,
+				     ARRAY_SIZE(stack_syncobjs),
 				     &syncobjs);
 	if (ret < 0)
 		return ret;
@@ -1321,7 +1335,7 @@  drm_syncobj_wait_ioctl(struct drm_device *dev, void *data,
 						 &first,
 						 pdeadline);
 
-	drm_syncobj_array_free(syncobjs, count);
+	drm_syncobj_array_free(syncobjs, count, stack_syncobjs);
 
 	if (timeout < 0)
 		return timeout;
@@ -1336,6 +1350,7 @@  drm_syncobj_timeline_wait_ioctl(struct drm_device *dev, void *data,
 				struct drm_file *file_private)
 {
 	struct drm_syncobj_timeline_wait *args = data;
+	struct drm_syncobj *stack_syncobjs[4];
 	ktime_t deadline, *pdeadline = NULL;
 	u32 count = args->count_handles;
 	struct drm_syncobj **syncobjs;
@@ -1361,6 +1376,8 @@  drm_syncobj_timeline_wait_ioctl(struct drm_device *dev, void *data,
 	ret = drm_syncobj_array_find(file_private,
 				     u64_to_user_ptr(args->handles),
 				     count,
+				     stack_syncobjs,
+				     ARRAY_SIZE(stack_syncobjs),
 				     &syncobjs);
 	if (ret < 0)
 		return ret;
@@ -1378,7 +1395,7 @@  drm_syncobj_timeline_wait_ioctl(struct drm_device *dev, void *data,
 						 &first,
 						 pdeadline);
 
-	drm_syncobj_array_free(syncobjs, count);
+	drm_syncobj_array_free(syncobjs, count, stack_syncobjs);
 
 	if (timeout < 0)
 		return timeout;
@@ -1496,6 +1513,7 @@  drm_syncobj_reset_ioctl(struct drm_device *dev, void *data,
 			struct drm_file *file_private)
 {
 	struct drm_syncobj_array *args = data;
+	struct drm_syncobj *stack_syncobjs[4];
 	struct drm_syncobj **syncobjs;
 	uint32_t i;
 	int ret;
@@ -1512,6 +1530,8 @@  drm_syncobj_reset_ioctl(struct drm_device *dev, void *data,
 	ret = drm_syncobj_array_find(file_private,
 				     u64_to_user_ptr(args->handles),
 				     args->count_handles,
+				     stack_syncobjs,
+				     ARRAY_SIZE(stack_syncobjs),
 				     &syncobjs);
 	if (ret < 0)
 		return ret;
@@ -1519,7 +1539,7 @@  drm_syncobj_reset_ioctl(struct drm_device *dev, void *data,
 	for (i = 0; i < args->count_handles; i++)
 		drm_syncobj_replace_fence(syncobjs[i], NULL);
 
-	drm_syncobj_array_free(syncobjs, args->count_handles);
+	drm_syncobj_array_free(syncobjs, args->count_handles, stack_syncobjs);
 
 	return 0;
 }
@@ -1529,6 +1549,7 @@  drm_syncobj_signal_ioctl(struct drm_device *dev, void *data,
 			 struct drm_file *file_private)
 {
 	struct drm_syncobj_array *args = data;
+	struct drm_syncobj *stack_syncobjs[4];
 	struct drm_syncobj **syncobjs;
 	uint32_t i;
 	int ret;
@@ -1545,6 +1566,8 @@  drm_syncobj_signal_ioctl(struct drm_device *dev, void *data,
 	ret = drm_syncobj_array_find(file_private,
 				     u64_to_user_ptr(args->handles),
 				     args->count_handles,
+				     stack_syncobjs,
+				     ARRAY_SIZE(stack_syncobjs),
 				     &syncobjs);
 	if (ret < 0)
 		return ret;
@@ -1555,7 +1578,7 @@  drm_syncobj_signal_ioctl(struct drm_device *dev, void *data,
 			break;
 	}
 
-	drm_syncobj_array_free(syncobjs, args->count_handles);
+	drm_syncobj_array_free(syncobjs, args->count_handles, stack_syncobjs);
 
 	return ret;
 }
@@ -1567,6 +1590,7 @@  drm_syncobj_timeline_signal_ioctl(struct drm_device *dev, void *data,
 	struct drm_syncobj_timeline_array *args = data;
 	uint64_t __user *points = u64_to_user_ptr(args->points);
 	uint32_t i, j, count = args->count_handles;
+	struct drm_syncobj *stack_syncobjs[4];
 	struct drm_syncobj **syncobjs;
 	struct dma_fence_chain **chains;
 	int ret;
@@ -1586,6 +1610,8 @@  drm_syncobj_timeline_signal_ioctl(struct drm_device *dev, void *data,
 	ret = drm_syncobj_array_find(file_private,
 				     u64_to_user_ptr(args->handles),
 				     count,
+				     stack_syncobjs,
+				     ARRAY_SIZE(stack_syncobjs),
 				     &syncobjs);
 	if (ret < 0)
 		return ret;
@@ -1622,7 +1648,7 @@  drm_syncobj_timeline_signal_ioctl(struct drm_device *dev, void *data,
 err_chains:
 	kfree(chains);
 out:
-	drm_syncobj_array_free(syncobjs, count);
+	drm_syncobj_array_free(syncobjs, count, stack_syncobjs);
 
 	return ret;
 }
@@ -1631,6 +1657,7 @@  int drm_syncobj_query_ioctl(struct drm_device *dev, void *data,
 			    struct drm_file *file_private)
 {
 	struct drm_syncobj_timeline_array *args = data;
+	struct drm_syncobj *stack_syncobjs[4];
 	struct drm_syncobj **syncobjs;
 	uint64_t __user *points = u64_to_user_ptr(args->points);
 	uint32_t i;
@@ -1651,6 +1678,8 @@  int drm_syncobj_query_ioctl(struct drm_device *dev, void *data,
 	ret = drm_syncobj_array_find(file_private,
 				     u64_to_user_ptr(args->handles),
 				     args->count_handles,
+				     stack_syncobjs,
+				     ARRAY_SIZE(stack_syncobjs),
 				     &syncobjs);
 	if (ret < 0)
 		return ret;
@@ -1694,7 +1723,7 @@  int drm_syncobj_query_ioctl(struct drm_device *dev, void *data,
 			break;
 		}
 	}
-	drm_syncobj_array_free(syncobjs, args->count_handles);
+	drm_syncobj_array_free(syncobjs, args->count_handles, stack_syncobjs);
 
 	return ret;
 }