[PATCH] drm/ttm: Merge hugepage attr changes in ttm_dma_page_put.

[Bas Nieuwenhuizen]

Every set_pages_array_wb call resulted in cross-core
interrupts and TLB flushes. Merge more of them for
less overhead.

This reduces the time needed to free a 1.6 GiB GTT WC
buffer as part of Vulkan CTS from  ~2 sec to < 0.25 sec.
(Allocation still takes more than 2 sec though)

Signed-off-by: Bas Nieuwenhuizen <basni at chromium.org>
---
 drivers/gpu/drm/ttm/ttm_page_alloc_dma.c | 31 ++++++++++++++++++------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
index 4c659405a008a..9440ba0a55116 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
@@ -299,6 +299,25 @@ static int set_pages_array_uc(struct page **pages, int addrinarray)
 #endif
 	return 0;
 }
+
+static int ttm_set_page_range_wb(struct page *p, unsigned long numpages)
+{
+#if IS_ENABLED(CONFIG_AGP)
+        unsigned long i;
+
+        for (i = 0; i < numpages; i++)
+                unmap_page_from_agp(p + i);
+#endif
+	return 0;
+}
+
+#else /* for !CONFIG_X86 */
+
+static int ttm_set_page_range_wb(struct page *p, unsigned long numpages)
+{
+	return set_memory_wb((unsigned long)page_address(p), numpages);
+}
+
 #endif /* for !CONFIG_X86 */
 
 static int ttm_set_pages_caching(struct dma_pool *pool,
@@ -387,18 +406,16 @@ static void ttm_pool_update_free_locked(struct dma_pool *pool,
 static void ttm_dma_page_put(struct dma_pool *pool, struct dma_page *d_page)
 {
 	struct page *page = d_page->p;
-	unsigned i, num_pages;
+	unsigned num_pages;
 	int ret;
 
 	/* Don't set WB on WB page pool. */
 	if (!(pool->type & IS_CACHED)) {
 		num_pages = pool->size / PAGE_SIZE;
-		for (i = 0; i < num_pages; ++i, ++page) {
-			ret = set_pages_array_wb(&page, 1);
-			if (ret) {
-				pr_err("%s: Failed to set %d pages to wb!\n",
-				       pool->dev_name, 1);
-			}
+		ret = ttm_set_page_range_wb(page, num_pages);
+		if (ret) {
+			pr_err("%s: Failed to set %d pages to wb!\n",
+			       pool->dev_name, num_pages);
 		}
 	}
 
-- 
2.18.0.233.g985f88cf7e-goog