Commit 32334c9b authored by Matthew Auld's avatar Matthew Auld
Browse files

drm/i915/gtt: ignore min_page_size for paging structures 



The min_page_size is only needed for pages inserted into the GTT, and
for our paging structures we only need at most 4K bytes, so simply
ignore the min_page_size restrictions here, otherwise we might see some
severe overallocation on some devices.

v2(Thomas): add some commentary

Signed-off-by: default avatarMatthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210625103824.558481-2-matthew.auld@intel.com
parent d22632c8

drivers/gpu/drm/i915/gt/intel_gtt.c

+13 −1
Original line number Diff line number Diff line
@@ -16,7 +16,19 @@ struct drm_i915_gem_object *alloc_pt_lmem(struct i915_address_space *vm, int sz) 
{

	struct drm_i915_gem_object *obj;



	obj = i915_gem_object_create_lmem(vm->i915, sz, 0);

	/*

	 * To avoid severe over-allocation when dealing with min_page_size

	 * restrictions, we override that behaviour here by allowing an object

	 * size and page layout which can be smaller. In practice this should be

	 * totally fine, since GTT paging structures are not typically inserted

	 * into the GTT.

	 *

	 * Note that we also hit this path for the scratch page, and for this

	 * case it might need to be 64K, but that should work fine here since we

	 * used the passed in size for the page size, which should ensure it

	 * also has the same alignment.

	 */

	obj = __i915_gem_object_create_lmem_with_ps(vm->i915, sz, sz, 0);

	/*

	 * Ensure all paging structures for this vm share the same dma-resv

	 * object underneath, with the idea that one object_lock() will lock