diff mbox series

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

Message ID 20201217230612.32397-1-john.stultz@linaro.org
State New
Headers show
Series [RFC,1/3] dma-buf: heaps: Add deferred-free-helper library code | expand

Commit Message

John Stultz Dec. 17, 2020, 11:06 p.m. UTC
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: 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>
---
 drivers/dma-buf/heaps/Kconfig                |   3 +
 drivers/dma-buf/heaps/Makefile               |   1 +
 drivers/dma-buf/heaps/deferred-free-helper.c | 136 +++++++++++++++++++
 drivers/dma-buf/heaps/deferred-free-helper.h |  15 ++
 4 files changed, 155 insertions(+)
 create mode 100644 drivers/dma-buf/heaps/deferred-free-helper.c
 create mode 100644 drivers/dma-buf/heaps/deferred-free-helper.h

Comments

Suren Baghdasaryan Dec. 22, 2020, 5:41 p.m. UTC | #1
Hi John,
Just a couple nits, otherwise looks sane to me.

On Thu, Dec 17, 2020 at 3:06 PM John Stultz <john.stultz@linaro.org> wrote:
>

> 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.


I suggest adding some more description for this API and how it can be
used. IIUC there are 2 uses: lazy deferred freeing using kthread, and
object pooling. no_pool parameter I think deserves some explanation
(disallows pooling when system is under memory pressure).

>

> As not all heaps will find this useful, its implemented as

> a optional helper library that heaps can utilize.

>

> 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>

> ---

>  drivers/dma-buf/heaps/Kconfig                |   3 +

>  drivers/dma-buf/heaps/Makefile               |   1 +

>  drivers/dma-buf/heaps/deferred-free-helper.c | 136 +++++++++++++++++++

>  drivers/dma-buf/heaps/deferred-free-helper.h |  15 ++

>  4 files changed, 155 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..ecf65204f714 100644

> --- a/drivers/dma-buf/heaps/Kconfig

> +++ b/drivers/dma-buf/heaps/Kconfig

> @@ -1,3 +1,6 @@

> +config DMABUF_HEAPS_DEFERRED_FREE

> +       bool

> +

>  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..b8f54860454f

> --- /dev/null

> +++ b/drivers/dma-buf/heaps/deferred-free-helper.c

> @@ -0,0 +1,136 @@

> +// 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;

> +wait_queue_head_t freelist_waitqueue;

> +struct task_struct *freelist_task;

> +static DEFINE_MUTEX(free_list_lock);

> +

> +enum {

> +       USE_POOL = 0,

> +       SKIP_POOL = 1,

> +};


This enum is used for a bool parameter. Either make it part of the
public API or eliminate and use bool instead.

> +

> +void deferred_free(struct deferred_freelist_item *item,

> +                  void (*free)(struct deferred_freelist_item*, bool),

> +                  size_t size)

> +{

> +       INIT_LIST_HEAD(&item->list);

> +       item->size = size;

> +       item->free = free;

> +

> +       mutex_lock(&free_list_lock);

> +       list_add(&item->list, &free_list);

> +       list_size += size;

> +       mutex_unlock(&free_list_lock);

> +       wake_up(&freelist_waitqueue);

> +}

> +

> +static size_t free_one_item(bool nopool)

> +{

> +       size_t size = 0;

> +       struct deferred_freelist_item *item;

> +

> +       mutex_lock(&free_list_lock);

> +       if (list_empty(&free_list)) {

> +               mutex_unlock(&free_list_lock);

> +               return 0;

> +       }

> +       item = list_first_entry(&free_list, struct deferred_freelist_item, list);

> +       list_del(&item->list);

> +       size = item->size;

> +       list_size -= size;

> +       mutex_unlock(&free_list_lock);

> +

> +       item->free(item, nopool);

> +       return size;

> +}

> +

> +static unsigned long get_freelist_size(void)

> +{

> +       unsigned long size;

> +

> +       mutex_lock(&free_list_lock);

> +       size = list_size;

> +       mutex_unlock(&free_list_lock);

> +       return size;

> +}

> +

> +static unsigned long freelist_shrink_count(struct shrinker *shrinker,

> +                                          struct shrink_control *sc)

> +{

> +       return get_freelist_size();

> +}

> +

> +static unsigned long freelist_shrink_scan(struct shrinker *shrinker,

> +                                         struct shrink_control *sc)

> +{

> +       int total_freed = 0;

> +

> +       if (sc->nr_to_scan == 0)

> +               return 0;

> +

> +       while (total_freed < sc->nr_to_scan) {

> +               int freed = free_one_item(SKIP_POOL);

> +

> +               if (!freed)

> +                       break;

> +

> +               total_freed += 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() > 0);

> +

> +               free_one_item(USE_POOL);

> +       }

> +

> +       return 0;

> +}

> +

> +static int deferred_freelist_init(void)

> +{

> +       list_size = 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("%s: creating thread for deferred free failed\n",

> +                      __func__);

> +               return -1;

> +       }

> +       sched_set_normal(freelist_task, 19);

> +

> +       return register_shrinker(&freelist_shrinker);

> +}

> +device_initcall(deferred_freelist_init);

> 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..09a2274a897c

> --- /dev/null

> +++ b/drivers/dma-buf/heaps/deferred-free-helper.h

> @@ -0,0 +1,15 @@

> +/* SPDX-License-Identifier: GPL-2.0 */

> +

> +#ifndef DEFERRED_FREE_HELPER_H

> +#define DEFERRED_FREE_HELPER_H

> +

> +struct deferred_freelist_item {

> +       size_t size;

> +       void (*free)(struct deferred_freelist_item *i, bool no_pool);

> +       struct list_head list;

> +};


I assume deferred_freelist_item gets embedded in a structure that is
actually being freed?

> +

> +void deferred_free(struct deferred_freelist_item *item,

> +                  void (*free)(struct deferred_freelist_item *i, bool no_pool),

> +                  size_t size);

> +#endif

> --

> 2.17.1

>
diff mbox series

Patch

diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
index a5eef06c4226..ecf65204f714 100644
--- a/drivers/dma-buf/heaps/Kconfig
+++ b/drivers/dma-buf/heaps/Kconfig
@@ -1,3 +1,6 @@ 
+config DMABUF_HEAPS_DEFERRED_FREE
+	bool
+
 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..b8f54860454f
--- /dev/null
+++ b/drivers/dma-buf/heaps/deferred-free-helper.c
@@ -0,0 +1,136 @@ 
+// 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;
+wait_queue_head_t freelist_waitqueue;
+struct task_struct *freelist_task;
+static DEFINE_MUTEX(free_list_lock);
+
+enum {
+	USE_POOL = 0,
+	SKIP_POOL = 1,
+};
+
+void deferred_free(struct deferred_freelist_item *item,
+		   void (*free)(struct deferred_freelist_item*, bool),
+		   size_t size)
+{
+	INIT_LIST_HEAD(&item->list);
+	item->size = size;
+	item->free = free;
+
+	mutex_lock(&free_list_lock);
+	list_add(&item->list, &free_list);
+	list_size += size;
+	mutex_unlock(&free_list_lock);
+	wake_up(&freelist_waitqueue);
+}
+
+static size_t free_one_item(bool nopool)
+{
+	size_t size = 0;
+	struct deferred_freelist_item *item;
+
+	mutex_lock(&free_list_lock);
+	if (list_empty(&free_list)) {
+		mutex_unlock(&free_list_lock);
+		return 0;
+	}
+	item = list_first_entry(&free_list, struct deferred_freelist_item, list);
+	list_del(&item->list);
+	size = item->size;
+	list_size -= size;
+	mutex_unlock(&free_list_lock);
+
+	item->free(item, nopool);
+	return size;
+}
+
+static unsigned long get_freelist_size(void)
+{
+	unsigned long size;
+
+	mutex_lock(&free_list_lock);
+	size = list_size;
+	mutex_unlock(&free_list_lock);
+	return size;
+}
+
+static unsigned long freelist_shrink_count(struct shrinker *shrinker,
+					   struct shrink_control *sc)
+{
+	return get_freelist_size();
+}
+
+static unsigned long freelist_shrink_scan(struct shrinker *shrinker,
+					  struct shrink_control *sc)
+{
+	int total_freed = 0;
+
+	if (sc->nr_to_scan == 0)
+		return 0;
+
+	while (total_freed < sc->nr_to_scan) {
+		int freed = free_one_item(SKIP_POOL);
+
+		if (!freed)
+			break;
+
+		total_freed += 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() > 0);
+
+		free_one_item(USE_POOL);
+	}
+
+	return 0;
+}
+
+static int deferred_freelist_init(void)
+{
+	list_size = 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("%s: creating thread for deferred free failed\n",
+		       __func__);
+		return -1;
+	}
+	sched_set_normal(freelist_task, 19);
+
+	return register_shrinker(&freelist_shrinker);
+}
+device_initcall(deferred_freelist_init);
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..09a2274a897c
--- /dev/null
+++ b/drivers/dma-buf/heaps/deferred-free-helper.h
@@ -0,0 +1,15 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef DEFERRED_FREE_HELPER_H
+#define DEFERRED_FREE_HELPER_H
+
+struct deferred_freelist_item {
+	size_t size;
+	void (*free)(struct deferred_freelist_item *i, bool no_pool);
+	struct list_head list;
+};
+
+void deferred_free(struct deferred_freelist_item *item,
+		   void (*free)(struct deferred_freelist_item *i, bool no_pool),
+		   size_t size);
+#endif