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Commit 5602452e authored by Tvrtko Ursulin's avatar Tvrtko Ursulin
Browse files

drm/i915: Use __sg_alloc_table_from_pages for userptr allocations 



With the addition of __sg_alloc_table_from_pages we can control
the maximum coalescing size and eliminate a separate path for
allocating backing store here.

Similar to 871dfbd6 ("drm/i915: Allow compaction upto
SWIOTLB max segment size") this enables more compact sg lists to
be created and so has a beneficial effect on workloads with many
and/or large objects of this class.

v2:
 * Rename helper to i915_sg_segment_size and fix swiotlb override.
 * Commit message update.

v3:
 * Actually include the swiotlb override fix.

v4:
 * Regroup parameters a bit. (Chris Wilson)

v5:
 * Rebase for swiotlb_max_segment.
 * Add DMA map failure handling as in abb0deac
   ("drm/i915: Fallback to single PAGE_SIZE segments for DMA remapping").

v6: Handle swiotlb_max_segment() returning 1. (Joonas Lahtinen)

v7: Rebase.
v8: Commit spelling fix.

Signed-off-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: linux-kernel@vger.kernel.org
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170803091417.23677-1-tvrtko.ursulin@linux.intel.com
parent 89d8589c

drivers/gpu/drm/i915/i915_drv.h

+15 −0
Original line number Diff line number Diff line
@@ -2828,6 +2828,21 @@ static inline struct scatterlist *__sg_next(struct scatterlist *sg) 
	     (((__iter).curr += PAGE_SIZE) < (__iter).max) ||		\

	     ((__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0))



static inline unsigned int i915_sg_segment_size(void)

{

	unsigned int size = swiotlb_max_segment();



	if (size == 0)

		return SCATTERLIST_MAX_SEGMENT;



	size = rounddown(size, PAGE_SIZE);

	/* swiotlb_max_segment_size can return 1 byte when it means one page. */

	if (size < PAGE_SIZE)

		size = PAGE_SIZE;



	return size;

}



static inline const struct intel_device_info *

intel_info(const struct drm_i915_private *dev_priv)

{

drivers/gpu/drm/i915/i915_gem.c

+1 −5
Original line number Diff line number Diff line
@@ -2303,7 +2303,7 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj) 
	struct sgt_iter sgt_iter;

	struct page *page;

	unsigned long last_pfn = 0;	/* suppress gcc warning */

	unsigned int max_segment;

	unsigned int max_segment = i915_sg_segment_size();

	gfp_t noreclaim;

	int ret;
@@ -2314,10 +2314,6 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj) 
	GEM_BUG_ON(obj->base.read_domains & I915_GEM_GPU_DOMAINS);

	GEM_BUG_ON(obj->base.write_domain & I915_GEM_GPU_DOMAINS);



	max_segment = swiotlb_max_segment();

	if (!max_segment)

		max_segment = rounddown(UINT_MAX, PAGE_SIZE);



	st = kmalloc(sizeof(*st), GFP_KERNEL);

	if (st == NULL)

		return ERR_PTR(-ENOMEM);

drivers/gpu/drm/i915/i915_gem_userptr.c

+29 −50
Original line number Diff line number Diff line
@@ -399,64 +399,42 @@ struct get_pages_work { 
	struct task_struct *task;

};



#if IS_ENABLED(CONFIG_SWIOTLB)

#define swiotlb_active() swiotlb_nr_tbl()

#else

#define swiotlb_active() 0

#endif



static int

st_set_pages(struct sg_table **st, struct page **pvec, int num_pages)

static struct sg_table *

__i915_gem_userptr_alloc_pages(struct drm_i915_gem_object *obj,

			       struct page **pvec, int num_pages)

{

	struct scatterlist *sg;

	int ret, n;



	*st = kmalloc(sizeof(**st), GFP_KERNEL);

	if (*st == NULL)

		return -ENOMEM;

	unsigned int max_segment = i915_sg_segment_size();

	struct sg_table *st;

	int ret;



	if (swiotlb_active()) {

		ret = sg_alloc_table(*st, num_pages, GFP_KERNEL);

		if (ret)

			goto err;

	st = kmalloc(sizeof(*st), GFP_KERNEL);

	if (!st)

		return ERR_PTR(-ENOMEM);



		for_each_sg((*st)->sgl, sg, num_pages, n)

			sg_set_page(sg, pvec[n], PAGE_SIZE, 0);

	} else {

		ret = sg_alloc_table_from_pages(*st, pvec, num_pages,

alloc_table:

	ret = __sg_alloc_table_from_pages(st, pvec, num_pages,

					  0, num_pages << PAGE_SHIFT,

					  max_segment,

					  GFP_KERNEL);

		if (ret)

			goto err;

	if (ret) {

		kfree(st);

		return ERR_PTR(ret);

	}



	return 0;

	ret = i915_gem_gtt_prepare_pages(obj, st);

	if (ret) {

		sg_free_table(st);



err:

	kfree(*st);

	*st = NULL;

	return ret;

		if (max_segment > PAGE_SIZE) {

			max_segment = PAGE_SIZE;

			goto alloc_table;

		}



static struct sg_table *

__i915_gem_userptr_set_pages(struct drm_i915_gem_object *obj,

			     struct page **pvec, int num_pages)

{

	struct sg_table *pages;

	int ret;



	ret = st_set_pages(&pages, pvec, num_pages);

	if (ret)

		return ERR_PTR(ret);



	ret = i915_gem_gtt_prepare_pages(obj, pages);

	if (ret) {

		sg_free_table(pages);

		kfree(pages);

		kfree(st);

		return ERR_PTR(ret);

	}



	return pages;

	return st;

}



static int
@@ -540,7 +518,8 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) 
		struct sg_table *pages = ERR_PTR(ret);



		if (pinned == npages) {

			pages = __i915_gem_userptr_set_pages(obj, pvec, npages);

			pages = __i915_gem_userptr_alloc_pages(obj, pvec,

							       npages);

			if (!IS_ERR(pages)) {

				__i915_gem_object_set_pages(obj, pages);

				pinned = 0;
@@ -661,7 +640,7 @@ i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj) 
		pages = __i915_gem_userptr_get_pages_schedule(obj);

		active = pages == ERR_PTR(-EAGAIN);

	} else {

		pages = __i915_gem_userptr_set_pages(obj, pvec, num_pages);

		pages = __i915_gem_userptr_alloc_pages(obj, pvec, num_pages);

		active = !IS_ERR(pages);

	}

	if (active)