lkml.org 
[lkml]   [2020]   [Dec]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[RFC][PATCH 1/3] dma-buf: heaps: Add deferred-free-helper library code
    Date
    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

    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
    --
    2.17.1
    \
     
     \ /
      Last update: 2020-12-18 00:09    [W:7.058 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site