From 954c4691218d9e3736dec089c0a5546391c8f3df Mon Sep 17 00:00:00 2001 From: Chris Wilson <chris@chris-wilson.co.uk> Date: Thu, 4 Aug 2016 16:32:26 +0100 Subject: [PATCH] drm/i915: Convert 4096 alignment request to 0 for drm_mm allocations 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 <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-10-git-send-email-chris@chris-wilson.co.uk --- 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 238d80e632798..e0e5256d4b782 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3072,6 +3072,15 @@ 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,