[Mesa-dev] [PATCH 6/7] winsys/amdgpu: increase the VM alignment to the MSB of the size for Gfx9

[Marek Olšák]

From: Marek Olšák <marek.olsak at amd.com>

---
 src/gallium/winsys/amdgpu/drm/amdgpu_bo.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/gallium/winsys/amdgpu/drm/amdgpu_bo.c b/src/gallium/winsys/amdgpu/drm/amdgpu_bo.c
index dd6c56600b7..3fc1da8b0b8 100644
--- a/src/gallium/winsys/amdgpu/drm/amdgpu_bo.c
+++ b/src/gallium/winsys/amdgpu/drm/amdgpu_bo.c
@@ -450,26 +450,36 @@ static struct amdgpu_winsys_bo *amdgpu_create_bo(struct amdgpu_winsys *ws,
    if (r) {
       fprintf(stderr, "amdgpu: Failed to allocate a buffer:\n");
       fprintf(stderr, "amdgpu:    size      : %"PRIu64" bytes\n", size);
       fprintf(stderr, "amdgpu:    alignment : %u bytes\n", alignment);
       fprintf(stderr, "amdgpu:    domains   : %u\n", initial_domain);
       goto error_bo_alloc;
    }
 
    va_gap_size = ws->check_vm ? MAX2(4 * alignment, 64 * 1024) : 0;
 
-   unsigned vm_alignment = alignment;
+   uint64_t vm_alignment = alignment;
 
    /* Increase the VM alignment for faster address translation. */
    if (size >= ws->info.pte_fragment_size)
       vm_alignment = MAX2(vm_alignment, ws->info.pte_fragment_size);
 
+   /* Gfx9: Increase the VM alignment to the most significant bit set
+    * in the size for faster address translation.
+    */
+   if (ws->info.chip_class >= GFX9) {
+      unsigned msb = util_last_bit64(size); /* 0 = no bit is set */
+      uint64_t msb_alignment = msb ? 1ull << (msb - 1) : 0;
+
+      vm_alignment = MAX2(vm_alignment, msb_alignment);
+   }
+
    r = amdgpu_va_range_alloc(ws->dev, amdgpu_gpu_va_range_general,
                              size + va_gap_size, vm_alignment, 0, &va, &va_handle,
                              (flags & RADEON_FLAG_32BIT ? AMDGPU_VA_RANGE_32_BIT : 0) |
 			     AMDGPU_VA_RANGE_HIGH);
    if (r)
       goto error_va_alloc;
 
    unsigned vm_flags = AMDGPU_VM_PAGE_READABLE |
                        AMDGPU_VM_PAGE_EXECUTABLE;
 
-- 
2.17.1