linux-kernel - [PATCH v9 3/5] dma-buf: system_heap: Add drm pagepool support to system heap

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Date:   Wed, 30 Jun 2021 01:34:19 +0000
From:   John Stultz <john.stultz@...aro.org>
To:     lkml <linux-kernel@...r.kernel.org>
Cc:     John Stultz <john.stultz@...aro.org>,
        Daniel Vetter <daniel@...ll.ch>,
        Christian Koenig <christian.koenig@....com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Liam Mark <lmark@...eaurora.org>,
        Chris Goldsworthy <cgoldswo@...eaurora.org>,
        Laura Abbott <labbott@...nel.org>,
        Brian Starkey <Brian.Starkey@....com>,
        Hridya Valsaraju <hridya@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Sandeep Patil <sspatil@...gle.com>,
        Daniel Mentz <danielmentz@...gle.com>,
        Ørjan Eide <orjan.eide@....com>,
        Robin Murphy <robin.murphy@....com>,
        Ezequiel Garcia <ezequiel@...labora.com>,
        Simon Ser <contact@...rsion.fr>,
        James Jones <jajones@...dia.com>, linux-media@...r.kernel.org,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH v9 3/5] dma-buf: system_heap: Add drm pagepool support to system heap

Utilize the drm pagepool code to speed up allocation
performance.

This is similar to the ION pagepool usage, but tries to
utilize generic code instead of a custom implementation.

Cc: Daniel Vetter <daniel@...ll.ch>
Cc: Christian Koenig <christian.koenig@....com>
Cc: Sumit Semwal <sumit.semwal@...aro.org>
Cc: Liam Mark <lmark@...eaurora.org>
Cc: Chris Goldsworthy <cgoldswo@...eaurora.org>
Cc: Laura Abbott <labbott@...nel.org>
Cc: Brian Starkey <Brian.Starkey@....com>
Cc: Hridya Valsaraju <hridya@...gle.com>
Cc: Suren Baghdasaryan <surenb@...gle.com>
Cc: Sandeep Patil <sspatil@...gle.com>
Cc: Daniel Mentz <danielmentz@...gle.com>
Cc: Ørjan Eide <orjan.eide@....com>
Cc: Robin Murphy <robin.murphy@....com>
Cc: Ezequiel Garcia <ezequiel@...labora.com>
Cc: Simon Ser <contact@...rsion.fr>
Cc: James Jones <jajones@...dia.com>
Cc: linux-media@...r.kernel.org
Cc: dri-devel@...ts.freedesktop.org
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
v2:
* Fix build issue caused by selecting PAGE_POOL w/o NET
  as Reported-by: kernel test robot <lkp@...el.com>
v3:
* Simplify the page zeroing logic a bit by using kmap_atomic
  instead of vmap as suggested by Daniel Mentz
v5:
* Shift away from networking page pool completely to
  dmabuf page pool implementation
v6:
* Switch again to using the drm_page_pool code shared w/
  ttm_pool
v7:
* Slight rework for drm_page_pool changes
v8:
* Rework to use the rewritten drm_page_pool logic
* Drop explicit buffer zeroing, as the drm_page_pool handles that
v9:
* Fix compiler warning Reported-by: kernel test robot <lkp@...el.com>
---
 drivers/dma-buf/heaps/Kconfig       |  1 +
 drivers/dma-buf/heaps/system_heap.c | 26 +++++++++++++++++++++++---
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
index a5eef06c4226..f19bf1f82bc2 100644
--- a/drivers/dma-buf/heaps/Kconfig
+++ b/drivers/dma-buf/heaps/Kconfig
@@ -1,6 +1,7 @@
 config DMABUF_HEAPS_SYSTEM
 	bool "DMA-BUF System Heap"
 	depends on DMABUF_HEAPS
+	select DRM_PAGE_POOL
 	help
 	  Choose this option to enable the system dmabuf heap. The system heap
 	  is backed by pages from the buddy allocator. If in doubt, say Y.
diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
index f57a39ddd063..85ceca2ed61d 100644
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -21,6 +21,8 @@
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 
+#include <drm/page_pool.h>
+
 static struct dma_heap *sys_heap;
 
 struct system_heap_buffer {
@@ -54,6 +56,7 @@ static gfp_t order_flags[] = {HIGH_ORDER_GFP, MID_ORDER_GFP, LOW_ORDER_GFP};
  */
 static const unsigned int orders[] = {8, 4, 0};
 #define NUM_ORDERS ARRAY_SIZE(orders)
+struct drm_page_pool pools[NUM_ORDERS];
 
 static struct sg_table *dup_sg_table(struct sg_table *table)
 {
@@ -282,18 +285,27 @@ static void system_heap_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map)
 	dma_buf_map_clear(map);
 }
 
+static void system_heap_free_pages(struct drm_page_pool *pool, struct page *p)
+{
+	__free_pages(p, pool->order);
+}
+
 static void system_heap_dma_buf_release(struct dma_buf *dmabuf)
 {
 	struct system_heap_buffer *buffer = dmabuf->priv;
 	struct sg_table *table;
 	struct scatterlist *sg;
-	int i;
+	int i, j;
 
 	table = &buffer->sg_table;
 	for_each_sg(table->sgl, sg, table->nents, i) {
 		struct page *page = sg_page(sg);
 
-		__free_pages(page, compound_order(page));
+		for (j = 0; j < NUM_ORDERS; j++) {
+			if (compound_order(page) == orders[j])
+				break;
+		}
+		drm_page_pool_add(&pools[j], page);
 	}
 	sg_free_table(table);
 	kfree(buffer);
@@ -324,7 +336,9 @@ static struct page *alloc_largest_available(unsigned long size,
 		if (max_order < orders[i])
 			continue;
 
-		page = alloc_pages(order_flags[i], orders[i]);
+		page = drm_page_pool_remove(&pools[i]);
+		if (!page)
+			page = alloc_pages(order_flags[i], orders[i]);
 		if (!page)
 			continue;
 		return page;
@@ -425,6 +439,12 @@ static const struct dma_heap_ops system_heap_ops = {
 static int system_heap_create(void)
 {
 	struct dma_heap_export_info exp_info;
+	int i;
+
+	for (i = 0; i < NUM_ORDERS; i++) {
+		drm_page_pool_init(&pools[i], orders[i],
+				   system_heap_free_pages);
+	}
 
 	exp_info.name = "system";
 	exp_info.ops = &system_heap_ops;
-- 
2.25.1