gpu: nvgpu: Initial MAP_BUFFER_BATCH implementation

Add batch support for mapping and unmapping. Batching essentially
helps transform some per-map/unmap overhead to per-batch overhead,
namely gk20a_busy()/gk20a_idle() calls, GPU L2 flushes, and GPU TLB
invalidates. Batching with size 64 has been measured to yield >20x
speed-up in low-level fixed-address mapping microbenchmarks.

Bug 1614735
Bug 1623949

Change-Id: Ie22b9caea5a7c3fc68a968d1b7f8488dfce72085
Signed-off-by: Sami Kiminki <skiminki@nvidia.com>
Reviewed-on: http://git-master/r/733231
(cherry picked from commit de4a7cfb93e8228a4a0c6a2815755a8df4531c91)
Reviewed-on: http://git-master/r/763812
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/gk20a.c b/drivers/gpu/nvgpu/gk20a/gk20a.c
index d5208e0d..5a25eecf 100644
--- a/drivers/gpu/nvgpu/gk20a/gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/gk20a.c
@@ -2033,6 +2033,8 @@ int gk20a_init_gpu_characteristics(struct gk20a *g)
         gpu->cbc_cache_line_size = g->gr.cacheline_size;
         gpu->cbc_comptags_per_line = g->gr.comptags_per_cacheline;
 
+        gpu->map_buffer_batch_limit = 256;
+
         return 0;
 }