freedreno: add bo cache

Workloads which create many transient buffers cause significant CPU
overhead in buffer allocation, zeroing, cache maint, and mmap setup.
By caching and re-using existing buffers, the CPU overhead drops
significantly.  See:

http://bloggingthemonkey.blogspot.com/2013/09/freedreno-update-moar-fps.html

A simple time based policy is used for purging the cache.  Once the
kernel supports it, we could use madvise style API to handle memory
pressure scenarios a bit better.

Signed-off-by: Rob Clark <robclark@freedesktop.org>

1 files changed, 17 insertions, 2 deletions

diff --git a/freedreno/kgsl/kgsl_bo.c b/freedreno/kgsl/kgsl_bo.c
index 0d019cb1..585851c7 100644
--- a/freedreno/kgsl/kgsl_bo.c
+++ b/freedreno/kgsl/kgsl_bo.c
@@ -80,9 +80,24 @@ static int kgsl_bo_offset(struct fd_bo *bo, uint64_t *offset)
 static int kgsl_bo_cpu_prep(struct fd_bo *bo, struct fd_pipe *pipe, uint32_t op)
 {
 	uint32_t timestamp = kgsl_bo_get_timestamp(to_kgsl_bo(bo));
-	if (timestamp) {
-		fd_pipe_wait(pipe, timestamp);
+
+	if (op & DRM_FREEDRENO_PREP_NOSYNC) {
+		uint32_t current;
+		int ret;
+
+		ret = kgsl_pipe_timestamp(to_kgsl_pipe(pipe), &current);
+		if (ret)
+			return ret;
+
+		if (timestamp > current)
+			return -EBUSY;
+
+		return 0;
 	}
+
+	if (timestamp)
+		fd_pipe_wait(pipe, timestamp);
+
 	return 0;
 }