[PATCH v4 1/3] dma-buf: heaps: Add deferred-free-helper library code

[PATCH v4 1/3] dma-buf: heaps: Add deferred-free-helper library code

[John Stultz]

This patch provides infrastructure for deferring buffer frees.

This is a feature ION provided which when used with some form
of a page pool, provides a nice performance boost in an
allocation microbenchmark. The reason it helps is it allows the
page-zeroing to be done out of the normal allocation/free path,
and pushed off to a kthread.

As not all heaps will find this useful, its implemented as
a optional helper library that heaps can utilize.

Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Liam Mark <lmark@codeaurora.org>
Cc: Chris Goldsworthy <cgoldswo@codeaurora.org>
Cc: Laura Abbott <labbott@kernel.org>
Cc: Brian Starkey <Brian.Starkey@arm.com>
Cc: Hridya Valsaraju <hridya@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sandeep Patil <sspatil@google.com>
Cc: Daniel Mentz <danielmentz@google.com>
Cc: Ørjan Eide <orjan.eide@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Ezequiel Garcia <ezequiel@collabora.com>
Cc: Simon Ser <contact@emersion.fr>
Cc: James Jones <jajones@nvidia.com>
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
v2:
* Fix sleep in atomic issue from using a mutex, by switching
  to a spinlock as Reported-by: kernel test robot <oliver.sang@intel.com>
* Cleanup API to use a reason enum for clarity and add some documentation
  comments as suggested by Suren Baghdasaryan.

v3:
* Minor tweaks so it can be built as a module
* A few small fixups suggested by Daniel Mentz

v4:
* Tweak from Daniel Mentz to make sure the shrinker
  count/freed values are tracked in pages not bytes
---
 drivers/dma-buf/heaps/Kconfig                |   3 +
 drivers/dma-buf/heaps/Makefile               |   1 +
 drivers/dma-buf/heaps/deferred-free-helper.c | 138 +++++++++++++++++++
 drivers/dma-buf/heaps/deferred-free-helper.h |  55 ++++++++
 4 files changed, 197 insertions(+)
 create mode 100644 drivers/dma-buf/heaps/deferred-free-helper.c
 create mode 100644 drivers/dma-buf/heaps/deferred-free-helper.h

diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
index a5eef06c4226..f7aef8bc7119 100644
--- a/drivers/dma-buf/heaps/Kconfig
+++ b/drivers/dma-buf/heaps/Kconfig
@@ -1,3 +1,6 @@
+config DMABUF_HEAPS_DEFERRED_FREE
+	tristate
+
 config DMABUF_HEAPS_SYSTEM
 	bool "DMA-BUF System Heap"
 	depends on DMABUF_HEAPS
diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-buf/heaps/Makefile
index 974467791032..4e7839875615 100644
--- a/drivers/dma-buf/heaps/Makefile
+++ b/drivers/dma-buf/heaps/Makefile
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_DMABUF_HEAPS_DEFERRED_FREE) += deferred-free-helper.o
 obj-$(CONFIG_DMABUF_HEAPS_SYSTEM)	+= system_heap.o
 obj-$(CONFIG_DMABUF_HEAPS_CMA)		+= cma_heap.o
diff --git a/drivers/dma-buf/heaps/deferred-free-helper.c b/drivers/dma-buf/heaps/deferred-free-helper.c
new file mode 100644
index 000000000000..0ba02de9dc1c
--- /dev/null
+++ b/drivers/dma-buf/heaps/deferred-free-helper.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Deferred dmabuf freeing helper
+ *
+ * Copyright (C) 2020 Linaro, Ltd.
+ *
+ * Based on the ION page pool code
+ * Copyright (C) 2011 Google, Inc.
+ */
+
+#include <linux/freezer.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/swap.h>
+#include <linux/sched/signal.h>
+
+#include "deferred-free-helper.h"
+
+static LIST_HEAD(free_list);
+static size_t list_size_pages;
+wait_queue_head_t freelist_waitqueue;
+struct task_struct *freelist_task;
+static DEFINE_SPINLOCK(free_list_lock);
+
+void deferred_free(struct deferred_freelist_item *item,
+		   void (*free)(struct deferred_freelist_item*,
+				enum df_reason),
+		   size_t size)
+{
+	unsigned long flags;
+
+	INIT_LIST_HEAD(&item->list);
+	item->size = size;
+	item->free = free;
+
+	spin_lock_irqsave(&free_list_lock, flags);
+	list_add(&item->list, &free_list);
+	list_size_pages += size >> PAGE_SHIFT;
+	spin_unlock_irqrestore(&free_list_lock, flags);
+	wake_up(&freelist_waitqueue);
+}
+EXPORT_SYMBOL_GPL(deferred_free);
+
+static size_t free_one_item(enum df_reason reason)
+{
+	unsigned long flags;
+	size_t size = 0;
+	struct deferred_freelist_item *item;
+
+	spin_lock_irqsave(&free_list_lock, flags);
+	if (list_empty(&free_list)) {
+		spin_unlock_irqrestore(&free_list_lock, flags);
+		return 0;
+	}
+	item = list_first_entry(&free_list, struct deferred_freelist_item, list);
+	list_del(&item->list);
+	size = item->size;
+	list_size_pages -= size >> PAGE_SHIFT;
+	spin_unlock_irqrestore(&free_list_lock, flags);
+
+	item->free(item, reason);
+	return size >> PAGE_SHIFT;
+}
+
+static unsigned long get_freelist_size_pages(void)
+{
+	unsigned long size;
+	unsigned long flags;
+
+	spin_lock_irqsave(&free_list_lock, flags);
+	size = list_size_pages;
+	spin_unlock_irqrestore(&free_list_lock, flags);
+	return size;
+}
+
+static unsigned long freelist_shrink_count(struct shrinker *shrinker,
+					   struct shrink_control *sc)
+{
+	return get_freelist_size_pages();
+}
+
+static unsigned long freelist_shrink_scan(struct shrinker *shrinker,
+					  struct shrink_control *sc)
+{
+	unsigned long total_freed = 0;
+
+	if (sc->nr_to_scan == 0)
+		return 0;
+
+	while (total_freed < sc->nr_to_scan) {
+		size_t pages_freed = free_one_item(DF_UNDER_PRESSURE);
+
+		if (!pages_freed)
+			break;
+
+		total_freed += pages_freed;
+	}
+
+	return total_freed;
+}
+
+static struct shrinker freelist_shrinker = {
+	.count_objects = freelist_shrink_count,
+	.scan_objects = freelist_shrink_scan,
+	.seeks = DEFAULT_SEEKS,
+	.batch = 0,
+};
+
+static int deferred_free_thread(void *data)
+{
+	while (true) {
+		wait_event_freezable(freelist_waitqueue,
+				     get_freelist_size_pages() > 0);
+
+		free_one_item(DF_NORMAL);
+	}
+
+	return 0;
+}
+
+static int deferred_freelist_init(void)
+{
+	list_size_pages = 0;
+
+	init_waitqueue_head(&freelist_waitqueue);
+	freelist_task = kthread_run(deferred_free_thread, NULL,
+				    "%s", "dmabuf-deferred-free-worker");
+	if (IS_ERR(freelist_task)) {
+		pr_err("Creating thread for deferred free failed\n");
+		return -1;
+	}
+	sched_set_normal(freelist_task, 19);
+
+	return register_shrinker(&freelist_shrinker);
+}
+module_init(deferred_freelist_init);
+MODULE_LICENSE("GPL v2");
+
diff --git a/drivers/dma-buf/heaps/deferred-free-helper.h b/drivers/dma-buf/heaps/deferred-free-helper.h
new file mode 100644
index 000000000000..18b44ac86ef6
--- /dev/null
+++ b/drivers/dma-buf/heaps/deferred-free-helper.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef DEFERRED_FREE_HELPER_H
+#define DEFERRED_FREE_HELPER_H
+
+/**
+ * df_reason - enum for reason why item was freed
+ *
+ * This provides a reason for why the free function was called
+ * on the item. This is useful when deferred_free is used in
+ * combination with a pagepool, so under pressure the page can
+ * be immediately freed.
+ *
+ * DF_NORMAL:         Normal deferred free
+ *
+ * DF_UNDER_PRESSURE: Free was called because the system
+ *                    is under memory pressure. Usually
+ *                    from a shrinker. Avoid allocating
+ *                    memory in the free call, as it may
+ *                    fail.
+ */
+enum df_reason {
+	DF_NORMAL,
+	DF_UNDER_PRESSURE,
+};
+
+/**
+ * deferred_freelist_item - item structure for deferred freelist
+ *
+ * This is to be added to the structure for whatever you want to
+ * defer freeing on.
+ *
+ * @size: size of the item to be freed
+ * @free: function pointer to be called when freeing the item
+ * @list: list entry for the deferred list
+ */
+struct deferred_freelist_item {
+	size_t size;
+	void (*free)(struct deferred_freelist_item *i,
+		     enum df_reason reason);
+	struct list_head list;
+};
+
+/**
+ * deferred_free - call to add item to the deferred free list
+ *
+ * @item: Pointer to deferred_freelist_item field of a structure
+ * @free: Function pointer to the free call
+ * @size: Size of the item to be freed
+ */
+void deferred_free(struct deferred_freelist_item *item,
+		   void (*free)(struct deferred_freelist_item *i,
+				enum df_reason reason),
+		   size_t size);
+#endif
-- 
2.25.1

[PATCH v4 2/3] dma-buf: system_heap: Add pagepool support to system heap

[John Stultz]

Reuse/abuse the pagepool code from the network 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@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Liam Mark <lmark@codeaurora.org>
Cc: Chris Goldsworthy <cgoldswo@codeaurora.org>
Cc: Laura Abbott <labbott@kernel.org>
Cc: Brian Starkey <Brian.Starkey@arm.com>
Cc: Hridya Valsaraju <hridya@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sandeep Patil <sspatil@google.com>
Cc: Daniel Mentz <danielmentz@google.com>
Cc: Ørjan Eide <orjan.eide@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Ezequiel Garcia <ezequiel@collabora.com>
Cc: Simon Ser <contact@emersion.fr>
Cc: James Jones <jajones@nvidia.com>
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
v2:
* Fix build issue caused by selecting PAGE_POOL w/o NET
  as Reported-by: kernel test robot <lkp@intel.com>
v3:
* Simplify the page zeroing logic a bit by using kmap_atomic
  instead of vmap as suggested by Daniel Mentz
---
 drivers/dma-buf/heaps/Kconfig       |  2 ++
 drivers/dma-buf/heaps/system_heap.c | 52 ++++++++++++++++++++++++++---
 2 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
index f7aef8bc7119..45c7d277448b 100644
--- a/drivers/dma-buf/heaps/Kconfig
+++ b/drivers/dma-buf/heaps/Kconfig
@@ -4,6 +4,8 @@ config DMABUF_HEAPS_DEFERRED_FREE
 config DMABUF_HEAPS_SYSTEM
 	bool "DMA-BUF System Heap"
 	depends on DMABUF_HEAPS
+	select NET
+	select 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 17e0e9a68baf..2addb6d832e0 100644
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -20,6 +20,7 @@
 #include <linux/scatterlist.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
+#include <net/page_pool.h>
 
 static struct dma_heap *sys_heap;
 
@@ -53,6 +54,7 @@ static gfp_t order_flags[] = {HIGH_ORDER_GFP, LOW_ORDER_GFP, LOW_ORDER_GFP};
  */
 static const unsigned int orders[] = {8, 4, 0};
 #define NUM_ORDERS ARRAY_SIZE(orders)
+struct page_pool *pools[NUM_ORDERS];
 
 static struct sg_table *dup_sg_table(struct sg_table *table)
 {
@@ -281,18 +283,43 @@ static void system_heap_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map)
 	dma_buf_map_clear(map);
 }
 
+static int system_heap_zero_buffer(struct system_heap_buffer *buffer)
+{
+	struct sg_table *sgt = &buffer->sg_table;
+	struct sg_page_iter piter;
+	struct page *p;
+	void *vaddr;
+	int ret = 0;
+
+	for_each_sgtable_page(sgt, &piter, 0) {
+		p = sg_page_iter_page(&piter);
+		vaddr = kmap_atomic(p);
+		memset(vaddr, 0, PAGE_SIZE);
+		kunmap_atomic(vaddr);
+	}
+
+	return ret;
+}
+
 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;
+
+	/* Zero the buffer pages before adding back to the pool */
+	system_heap_zero_buffer(buffer);
 
 	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;
+		}
+		page_pool_put_full_page(pools[j], page, false);
 	}
 	sg_free_table(table);
 	kfree(buffer);
@@ -322,8 +349,7 @@ static struct page *alloc_largest_available(unsigned long size,
 			continue;
 		if (max_order < orders[i])
 			continue;
-
-		page = alloc_pages(order_flags[i], orders[i]);
+		page = page_pool_alloc_pages(pools[i], order_flags[i]);
 		if (!page)
 			continue;
 		return page;
@@ -428,6 +454,24 @@ 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++) {
+		struct page_pool_params pp;
+
+		memset(&pp, 0, sizeof(pp));
+		pp.order = orders[i];
+		pools[i] = page_pool_create(&pp);
+
+		if (IS_ERR(pools[i])) {
+			int j;
+
+			pr_err("%s: page pool creation failed!\n", __func__);
+			for (j = 0; j < i; j++)
+				page_pool_destroy(pools[j]);
+			return PTR_ERR(pools[i]);
+		}
+	}
 
 	exp_info.name = "system";
 	exp_info.ops = &system_heap_ops;
-- 
2.25.1

[PATCH v4 3/3] dma-buf: system_heap: Add deferred freeing to the system heap

[John Stultz]

Utilize the deferred free helper library in the system heap.

This provides a nice performance bump and puts the
system heap performance on par with ION.

Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Liam Mark <lmark@codeaurora.org>
Cc: Chris Goldsworthy <cgoldswo@codeaurora.org>
Cc: Laura Abbott <labbott@kernel.org>
Cc: Brian Starkey <Brian.Starkey@arm.com>
Cc: Hridya Valsaraju <hridya@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sandeep Patil <sspatil@google.com>
Cc: Daniel Mentz <danielmentz@google.com>
Cc: Ørjan Eide <orjan.eide@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Ezequiel Garcia <ezequiel@collabora.com>
Cc: Simon Ser <contact@emersion.fr>
Cc: James Jones <jajones@nvidia.com>
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
v2:
* Rework deferred-free api to use reason enum as suggested by
  Suren Baghdasaryan
---
 drivers/dma-buf/heaps/Kconfig       |  1 +
 drivers/dma-buf/heaps/system_heap.c | 32 ++++++++++++++++++++++-------
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
index 45c7d277448b..2276420ae905 100644
--- a/drivers/dma-buf/heaps/Kconfig
+++ b/drivers/dma-buf/heaps/Kconfig
@@ -6,6 +6,7 @@ config DMABUF_HEAPS_SYSTEM
 	depends on DMABUF_HEAPS
 	select NET
 	select PAGE_POOL
+	select DMABUF_HEAPS_DEFERRED_FREE
 	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 2addb6d832e0..fe122b5eff10 100644
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -22,6 +22,8 @@
 #include <linux/vmalloc.h>
 #include <net/page_pool.h>
 
+#include "deferred-free-helper.h"
+
 static struct dma_heap *sys_heap;
 
 struct system_heap_buffer {
@@ -32,6 +34,7 @@ struct system_heap_buffer {
 	struct sg_table sg_table;
 	int vmap_cnt;
 	void *vaddr;
+	struct deferred_freelist_item deferred_free;
 };
 
 struct dma_heap_attachment {
@@ -301,30 +304,45 @@ static int system_heap_zero_buffer(struct system_heap_buffer *buffer)
 	return ret;
 }
 
-static void system_heap_dma_buf_release(struct dma_buf *dmabuf)
+static void system_heap_buf_free(struct deferred_freelist_item *item,
+				 enum df_reason reason)
 {
-	struct system_heap_buffer *buffer = dmabuf->priv;
+	struct system_heap_buffer *buffer;
 	struct sg_table *table;
 	struct scatterlist *sg;
 	int i, j;
 
+	buffer = container_of(item, struct system_heap_buffer, deferred_free);
 	/* Zero the buffer pages before adding back to the pool */
-	system_heap_zero_buffer(buffer);
+	if (reason == DF_NORMAL)
+		if (system_heap_zero_buffer(buffer))
+			reason = DF_UNDER_PRESSURE; // On failure, just free
 
 	table = &buffer->sg_table;
 	for_each_sg(table->sgl, sg, table->nents, i) {
 		struct page *page = sg_page(sg);
 
-		for (j = 0; j < NUM_ORDERS; j++) {
-			if (compound_order(page) == orders[j])
-				break;
+		if (reason == DF_UNDER_PRESSURE) {
+			__free_pages(page, compound_order(page));
+		} else {
+			for (j = 0; j < NUM_ORDERS; j++) {
+				if (compound_order(page) == orders[j])
+					break;
+			}
+			page_pool_put_full_page(pools[j], page, false);
 		}
-		page_pool_put_full_page(pools[j], page, false);
 	}
 	sg_free_table(table);
 	kfree(buffer);
 }
 
+static void system_heap_dma_buf_release(struct dma_buf *dmabuf)
+{
+	struct system_heap_buffer *buffer = dmabuf->priv;
+
+	deferred_free(&buffer->deferred_free, system_heap_buf_free, buffer->len);
+}
+
 static const struct dma_buf_ops system_heap_buf_ops = {
 	.attach = system_heap_attach,
 	.detach = system_heap_detach,
-- 
2.25.1