As we always allocate in chunks of 4096 (that being both the PAGE_SIZE
and our own GTT_PAGE_SIZE), we know that all results from the drm_mm are
aligned to at least 4096. The drm_mm allocator itself is optimised for
alignment == 0, and so by converting alignments of 4096 to 0 we can
satisfy our own requirements and still hit the faster path.
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
---
drivers/gpu/drm/i915/i915_gem.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 772b9739fdef..e1f1103b5d7b 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3068,6 +3068,15 @@ i915_gem_object_insert_into_vm(struct
drm_i915_gem_object *obj,
alloc_flag = DRM_MM_CREATE_DEFAULT;
}
+ /* We only allocate in PAGE_SIZE/GTT_PAGE_SIZE (4096) chunks,
+ * so we know that we always have a minimum alignment of 4096.
+ * The drm_mm range manager is optimised to return results
+ * with zero alignment, so where possible use the optimal
+ * path.
+ */
+ if (alignment <= 4096)
+ alignment = 0;
+
search_free:
ret = drm_mm_insert_node_in_range_generic(&vm->mm, &vma->node,
size, alignment,
--
2.8.1
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