intel: Add more intermediate sizes of cache buckets between powers of 2.

We had two cases recently where the rounding to powers of two hurt
badly: 4:2:0 YUV HD video frames would round up from 2.2MB to 4MB, and
Urban Terror was hitting aperture size limitations.  For UT, this is
because mipmap trees for power of two texture sizes will land right in
the middle between two cache buckets.

By giving a few more sizes between powers of two, Urban Terror on my
945 ends up consuming 207MB of GEM objects instead of 272MB, and HD
video decode on Ironlake goes from 99MB to 75MB.

cairo-perf-diff of the benchmarks for gl and xlib shows a 1.09x and
1.06x speedup and a 1.07x, 1.08x, and 1.11x slowdown.  From this, I
think this patch was really a no-op in terms of performance for these
CPU-bound workloads.

1 files changed, 48 insertions, 15 deletions

diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c
index 861cf0e8..33f9b44d 100644
--- a/intel/intel_bufmgr_gem.c
+++ b/intel/intel_bufmgr_gem.c
@@ -66,6 +66,8 @@
 		fprintf(stderr, __VA_ARGS__);		\
 } while (0)
 
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
 typedef struct _drm_intel_bo_gem drm_intel_bo_gem;
 
 struct drm_intel_gem_bo_bucket {
@@ -73,10 +75,6 @@ struct drm_intel_gem_bo_bucket {
 	unsigned long size;
 };
 
-/* Only cache objects up to 64MB.  Bigger than that, and the rounding of the
- * size makes many operations fail that wouldn't otherwise.
- */
-#define DRM_INTEL_GEM_BO_BUCKETS	14
 typedef struct _drm_intel_bufmgr_gem {
 	drm_intel_bufmgr bufmgr;
 
@@ -93,7 +91,8 @@ typedef struct _drm_intel_bufmgr_gem {
 	int exec_count;
 
 	/** Array of lists of cached gem objects of power-of-two sizes */
-	struct drm_intel_gem_bo_bucket cache_bucket[DRM_INTEL_GEM_BO_BUCKETS];
+	struct drm_intel_gem_bo_bucket cache_bucket[14 * 4];
+	int num_buckets;
 
 	uint64_t gtt_size;
 	int available_fences;
@@ -285,7 +284,7 @@ drm_intel_gem_bo_bucket_for_size(drm_intel_bufmgr_gem *bufmgr_gem,
 {
 	int i;
 
-	for (i = 0; i < DRM_INTEL_GEM_BO_BUCKETS; i++) {
+	for (i = 0; i < bufmgr_gem->num_buckets; i++) {
 		struct drm_intel_gem_bo_bucket *bucket =
 		    &bufmgr_gem->cache_bucket[i];
 		if (bucket->size >= size) {
@@ -830,7 +829,7 @@ drm_intel_gem_cleanup_bo_cache(drm_intel_bufmgr_gem *bufmgr_gem, time_t time)
 {
 	int i;
 
-	for (i = 0; i < DRM_INTEL_GEM_BO_BUCKETS; i++) {
+	for (i = 0; i < bufmgr_gem->num_buckets; i++) {
 		struct drm_intel_gem_bo_bucket *bucket =
 		    &bufmgr_gem->cache_bucket[i];
 
@@ -1258,7 +1257,7 @@ drm_intel_bufmgr_gem_destroy(drm_intel_bufmgr *bufmgr)
 	pthread_mutex_destroy(&bufmgr_gem->lock);
 
 	/* Free any cached buffer objects we were going to reuse */
-	for (i = 0; i < DRM_INTEL_GEM_BO_BUCKETS; i++) {
+	for (i = 0; i < bufmgr_gem->num_buckets; i++) {
 		struct drm_intel_gem_bo_bucket *bucket =
 		    &bufmgr_gem->cache_bucket[i];
 		drm_intel_bo_gem *bo_gem;
@@ -1989,6 +1988,45 @@ drm_intel_gem_bo_references(drm_intel_bo *bo, drm_intel_bo *target_bo)
 	return 0;
 }
 
+static void
+add_bucket(drm_intel_bufmgr_gem *bufmgr_gem, int size)
+{
+	unsigned int i = bufmgr_gem->num_buckets;
+
+	assert(i < ARRAY_SIZE(bufmgr_gem->cache_bucket));
+
+	DRMINITLISTHEAD(&bufmgr_gem->cache_bucket[i].head);
+	bufmgr_gem->cache_bucket[i].size = size;
+	bufmgr_gem->num_buckets++;
+}
+
+static void
+init_cache_buckets(drm_intel_bufmgr_gem *bufmgr_gem)
+{
+	unsigned long size, cache_max_size = 64 * 1024 * 1024;
+
+	/* OK, so power of two buckets was too wasteful of memory.
+	 * Give 3 other sizes between each power of two, to hopefully
+	 * cover things accurately enough.  (The alternative is
+	 * probably to just go for exact matching of sizes, and assume
+	 * that for things like composited window resize the tiled
+	 * width/height alignment and rounding of sizes to pages will
+	 * get us useful cache hit rates anyway)
+	 */
+	add_bucket(bufmgr_gem, 4096);
+	add_bucket(bufmgr_gem, 4096 * 2);
+	add_bucket(bufmgr_gem, 4096 * 3);
+
+	/* Initialize the linked lists for BO reuse cache. */
+	for (size = 4 * 4096; size <= cache_max_size; size *= 2) {
+		add_bucket(bufmgr_gem, size);
+
+		add_bucket(bufmgr_gem, size + size * 1 / 4);
+		add_bucket(bufmgr_gem, size + size * 2 / 4);
+		add_bucket(bufmgr_gem, size + size * 3 / 4);
+	}
+}
+
 /**
  * Initializes the GEM buffer manager, which uses the kernel to allocate, map,
  * and manage map buffer objections.
@@ -2001,8 +2039,7 @@ drm_intel_bufmgr_gem_init(int fd, int batch_size)
 	drm_intel_bufmgr_gem *bufmgr_gem;
 	struct drm_i915_gem_get_aperture aperture;
 	drm_i915_getparam_t gp;
-	int ret, i;
-	unsigned long size;
+	int ret;
 	int exec2 = 0, has_bsd = 0;
 
 	bufmgr_gem = calloc(1, sizeof(*bufmgr_gem));
@@ -2128,11 +2165,7 @@ drm_intel_bufmgr_gem_init(int fd, int batch_size)
 	    drm_intel_gem_get_pipe_from_crtc_id;
 	bufmgr_gem->bufmgr.bo_references = drm_intel_gem_bo_references;
 
-	/* Initialize the linked lists for BO reuse cache. */
-	for (i = 0, size = 4096; i < DRM_INTEL_GEM_BO_BUCKETS; i++, size *= 2) {
-		DRMINITLISTHEAD(&bufmgr_gem->cache_bucket[i].head);
-		bufmgr_gem->cache_bucket[i].size = size;
-	}
+	init_cache_buckets(bufmgr_gem);
 
 	return &bufmgr_gem->bufmgr;
 }