gpu: nvgpu: optimize duplicate buffer lookup in case of fixed offsets

In gk20a_vm_map_duplicate_locked(), we always do a linear search
in rb-tree to find a duplicate entry of the buffer

In case NVGPU_AS_MAP_BUFFER_FLAGS_FIXED_OFFSET is set, we first
traverse whole rb-tree linearly and then compare offset_align
with the address searched from rb-tree

If size of rb-tree is very large this linear lookup takes upto
7mS and causes huge delays

Hence in case of NVGPU_AS_MAP_BUFFER_FLAGS_FIXED_OFFSET, we can
use offset_align to perform a binary search on rb-tree and then
verify that dmabuf and kind match with the node obtained from
the search
This saves a lot of time per-lookup

Bug 1874516

Change-Id: Ia4924b64d66e586c14341ae2e2283beac394bf6f
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/1309343
Reviewed-by: svccoveritychecker <svccoveritychecker@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 15 insertions, 8 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/mm_gk20a.c b/drivers/gpu/nvgpu/gk20a/mm_gk20a.c
index c91acbd2..c95e744e 100644
--- a/drivers/gpu/nvgpu/gk20a/mm_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/mm_gk20a.c
@@ -2061,19 +2061,26 @@ static u64 gk20a_vm_map_duplicate_locked(struct vm_gk20a *vm,
         struct gk20a *g = gk20a_from_vm(vm);
         struct mapped_buffer_node *mapped_buffer = NULL;
 
-        mapped_buffer =
-                find_mapped_buffer_reverse_locked(&vm->mapped_buffers,
+        if (flags & NVGPU_AS_MAP_BUFFER_FLAGS_FIXED_OFFSET) {
+                mapped_buffer = find_mapped_buffer_locked(&vm->mapped_buffers,
+                                                          offset_align);
+                if (!mapped_buffer)
+                        return 0;
+
+                if (mapped_buffer->dmabuf != dmabuf ||
+                    mapped_buffer->kind != (u32)kind)
+                        return 0;
+        } else {
+                mapped_buffer =
+                        find_mapped_buffer_reverse_locked(&vm->mapped_buffers,
                                                   dmabuf, kind);
-        if (!mapped_buffer)
-                return 0;
+                if (!mapped_buffer)
+                        return 0;
+        }
 
         if (mapped_buffer->flags != flags)
                 return 0;
 
-        if (flags & NVGPU_AS_MAP_BUFFER_FLAGS_FIXED_OFFSET &&
-            mapped_buffer->addr != offset_align)
-                return 0;
-
         BUG_ON(mapped_buffer->vm != vm);
 
         /* mark the buffer as used */