[PATCH] drm/ttm: optimize pool allocations a bit

[Christian König]

If we got a page pool use it as much as possible.

If we can't get more pages from the pool allocate as much as possible.

Only if that still doesn't work reduce the order and try again.

Signed-off-by: Christian König <christian.koenig at amd.com>
---
 drivers/gpu/drm/ttm/ttm_pool.c | 81 ++++++++++++++++++++++++----------
 1 file changed, 57 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
index 21b61631f73a..cf15874cf380 100644
--- a/drivers/gpu/drm/ttm/ttm_pool.c
+++ b/drivers/gpu/drm/ttm/ttm_pool.c
@@ -344,6 +344,27 @@ static unsigned int ttm_pool_page_order(struct ttm_pool *pool, struct page *p)
 	return p->private;
 }
 
+/* Called when we got a page, either from a pool or newly allocated */
+int ttm_pool_page_allocated(struct ttm_pool *pool, unsigned int order,
+			    struct page *p, dma_addr_t **dma_addr,
+			    unsigned long *num_pages, struct page ***pages)
+{
+	unsigned int i;
+	int r;
+
+	if (*dma_addr) {
+		r = ttm_pool_map(pool, order, p, dma_addr);
+		if (r)
+			return r;
+	}
+
+	*num_pages -= 1 << order;
+	for (i = 1 << order; i; --i)
+		*((*pages)++) = p++;
+
+	return 0;
+}
+
 /**
  * ttm_pool_alloc - Fill a ttm_tt object
  *
@@ -385,45 +406,57 @@ int ttm_pool_alloc(struct ttm_pool *pool, struct ttm_tt *tt,
 	for (order = min_t(unsigned int, MAX_ORDER - 1, __fls(num_pages));
 	     num_pages;
 	     order = min_t(unsigned int, order, __fls(num_pages))) {
-		bool apply_caching = false;
 		struct ttm_pool_type *pt;
 
 		pt = ttm_pool_select_type(pool, tt->caching, order);
 		p = pt ? ttm_pool_type_take(pt) : NULL;
 		if (p) {
-			apply_caching = true;
-		} else {
-			p = ttm_pool_alloc_page(pool, gfp_flags, order);
-			if (p && PageHighMem(p))
-				apply_caching = true;
-		}
-
-		if (!p) {
-			if (order) {
-				--order;
-				continue;
-			}
-			r = -ENOMEM;
-			goto error_free_all;
-		}
-
-		if (apply_caching) {
 			r = ttm_pool_apply_caching(caching, pages,
 						   tt->caching);
 			if (r)
 				goto error_free_page;
-			caching = pages + (1 << order);
+
+			while (p) {
+				r = ttm_pool_page_allocated(pool, order, p,
+							    &dma_addr,
+							    &num_pages,
+							    &pages);
+				if (r)
+					goto error_free_page;
+
+				if (num_pages < (1 << order))
+					break;
+
+				p = ttm_pool_type_take(pt);
+			}
+			caching = pages;
 		}
 
-		if (dma_addr) {
-			r = ttm_pool_map(pool, order, p, &dma_addr);
+		while (num_pages >= (1 << order) &&
+		       (p = ttm_pool_alloc_page(pool, gfp_flags, order))) {
+
+			if (PageHighMem(p)) {
+				r = ttm_pool_apply_caching(caching, pages,
+							   tt->caching);
+				if (r)
+					goto error_free_page;
+			}
+			r = ttm_pool_page_allocated(pool, order, p, &dma_addr,
+						    &num_pages, &pages);
 			if (r)
 				goto error_free_page;
+			if (PageHighMem(p))
+				caching = pages;
 		}
 
-		num_pages -= 1 << order;
-		for (i = 1 << order; i; --i)
-			*(pages++) = p++;
+		if (!p) {
+			if (order) {
+				--order;
+				continue;
+			}
+			r = -ENOMEM;
+			goto error_free_all;
+		}
 	}
 
 	r = ttm_pool_apply_caching(caching, pages, tt->caching);
-- 
2.34.1