gpu-paging: Support asynchronous paging

- Fully enables *_ASYNC API
- Allows page mapping to be overlapped with I/O, resulting in an 11% speedup
  to synchronous reads

Benchmarks, 1,000 iters, before:
gpu_paging_speed, write: 185.5ms +/- 3.58
gpu_paging_speed, read: 180.5ms +/- 1.42
gpu_paging_overhead_speed, write start: 183.3ms +/- 3.89
gpu_paging_overhead_speed, write finish: 3.4ms +/- 2.61
gpu_paging_overhead_speed, read start: 181.6ms +/- 3.34
gpu_paging_overhead_speed, read finish: 41.1ms +/- 2.69

Benchmarks, 1,000 iters, after:
gpu_paging_speed, write: 185.8ms +/- 3.70
gpu_paging_speed, read: 161.3ms +/- 0.97
gpu_paging_overhead_speed, write start: 38.9ms +/- 5.47
gpu_paging_overhead_speed, write finish: 3.1ms +/- 2.42
gpu_paging_overhead_speed, read start: 79.4 +/- 6.42
gpu_paging_overhead_speed, read finish: 44.3 +/- 1.53

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/os/linux/vm.c b/drivers/gpu/nvgpu/os/linux/vm.c
index fcb58ac4..9cd17981 100644
--- a/drivers/gpu/nvgpu/os/linux/vm.c
+++ b/drivers/gpu/nvgpu/os/linux/vm.c
@@ -262,6 +262,7 @@ int nvgpu_vm_map_linux(struct vm_gk20a *vm,
         mapped_buffer->os_priv.dmabuf = dmabuf;
         mapped_buffer->os_priv.attachment = attachment;
         mapped_buffer->os_priv.sgt    = sgt;
+        init_completion(&mapped_buffer->os_priv.swap_io_done);
         nvmap_priv = nvmap_get_priv_list(dmabuf);
         if (!IS_ERR(nvmap_priv))
                 list_add(&mapped_buffer->os_priv.nvmap_priv_entry, nvmap_priv);