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[209.85.220.41]) by mx.google.com with SMTPS id z1sor580737pln.19.2021.03.04.15.20.19 for (Google Transport Security); Thu, 04 Mar 2021 15:20:19 -0800 (PST) Received-SPF: pass (google.com: domain of john.stultz@linaro.org designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=VAF9dFmB; spf=pass (google.com: domain of john.stultz@linaro.org designates 209.85.220.41 as permitted sender) smtp.mailfrom=john.stultz@linaro.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=BDAhVL6wLP9xE6Ae/kz68nSPm1bB9OfmCVC762Iy0sQ=; b=VAF9dFmBRjgsUgge9Qfdi/fx4I196F2rtVlBxmfloWQcKsFx0Ohhh86UkuQPTl85Sr Ph2eCaVFDXlVw6hshYuyKZcvffBhmbMWP3pMQQljJ13ucG9jIjOHXvW0+a0lJJyc4DpD j3G6QQyfD7On1IB6317wC8D/7pzX4jHMhKWJk2BYZcNv25VoeXL6A7r3pRgYp3o43dof UCMCzyyX9N8Lns5Ycep2tXdqulzOVCHx2wOaunUDySxEVjYiwoefivMpPz4cEnvKqJtr tKPNqeIYQH/jFBtq4eHvxMGIcwvOKgR/aGZHUOSWc/Ptrf1v5csFxb6GIziC+Vp5d58T zkWQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=BDAhVL6wLP9xE6Ae/kz68nSPm1bB9OfmCVC762Iy0sQ=; b=qowxfzF75aPdWbD1/vskFqm53QTqBDOrbMMQrle6HxgIR6JtmRxVcfWzZ/K0U7vD/b jOMXUmxKR8rDVS0G3Spq6mjOzUCHKMsXN84AP6q6jbZH0bKKrSEFXFZ3bAoS+KazbZl5 h/AM95lqR4mTjI7D88mGGJVVEluG4k/KQ5ZHKdza9jTeItLVmLk58mJPTs4/Vq3B356M Z/kyuxFNgq3ZntMczMcaezK+pJTIIkHnblj1Mx4MEdy1Sv9fcnqZP6pnQJtoahPLq9hE fmvezjhxwTQ324USgEWK4P8+5qr1Iix7eGy7bcrFX6XjFZVnpQx1XUy3qFl3BqGPdfLG W1Pw== X-Gm-Message-State: AOAM531/O4kpcLy/2dwYtllQUTWJTSGbEsEN1ZWWZ7+XU8e48TwP8yeN E5A/Btu64QyTjoIbOPd9ZB5CcdBI X-Google-Smtp-Source: ABdhPJwp99E/EUxAulMiCQS4Ao2Fiu1PPZ4ZTnj7wchTGh8r5Pg2AiqLSP40UXYFh40cR4tGdwEkRQ== X-Received: by 2002:a17:902:b48b:b029:e3:7808:aab4 with SMTP id y11-20020a170902b48bb02900e37808aab4mr5951588plr.54.1614900019600; Thu, 04 Mar 2021 15:20:19 -0800 (PST) Return-Path: Received: from localhost.localdomain ([2601:1c2:680:1319:692:26ff:feda:3a81]) by smtp.gmail.com with ESMTPSA id u66sm429290pfc.72.2021.03.04.15.20.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Mar 2021 15:20:18 -0800 (PST) From: John Stultz To: lkml Cc: John Stultz , Daniel Vetter , Christian Koenig , Sumit Semwal , Liam Mark , Chris Goldsworthy , Laura Abbott , Brian Starkey , Hridya Valsaraju , Suren Baghdasaryan , Sandeep Patil , Daniel Mentz , =?utf-8?q?=C3=98rjan_Eide?= , Robin Murphy , Ezequiel Garcia , Simon Ser , James Jones , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: [PATCH v8 3/5] dma-buf: heaps: Add deferred-free-helper library code Date: Thu, 4 Mar 2021 23:20:09 +0000 Message-Id: <20210304232011.1479036-4-john.stultz@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210304232011.1479036-1-john.stultz@linaro.org> References: <20210304232011.1479036-1-john.stultz@linaro.org> MIME-Version: 1.0 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 Cc: Christian Koenig Cc: Sumit Semwal Cc: Liam Mark Cc: Chris Goldsworthy Cc: Laura Abbott Cc: Brian Starkey Cc: Hridya Valsaraju Cc: Suren Baghdasaryan Cc: Sandeep Patil Cc: Daniel Mentz Cc: Ørjan Eide Cc: Robin Murphy Cc: Ezequiel Garcia Cc: Simon Ser Cc: James Jones Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: John Stultz --- v2: * Fix sleep in atomic issue from using a mutex, by switching to a spinlock as Reported-by: kernel test robot * 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 v5: * Fix up page count tracking as suggested by Suren Baghdasaryan v7: * Rework accounting to use nr_pages rather then size, as suggested by Suren Baghdasaryan --- 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 -- 2.25.1 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..e19c8b68dfeb --- /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 +#include +#include +#include +#include + +#include "deferred-free-helper.h" + +static LIST_HEAD(free_list); +static size_t list_nr_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 nr_pages) +{ + unsigned long flags; + + INIT_LIST_HEAD(&item->list); + item->nr_pages = nr_pages; + item->free = free; + + spin_lock_irqsave(&free_list_lock, flags); + list_add(&item->list, &free_list); + list_nr_pages += nr_pages; + 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 nr_pages; + 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); + nr_pages = item->nr_pages; + list_nr_pages -= nr_pages; + spin_unlock_irqrestore(&free_list_lock, flags); + + item->free(item, reason); + return nr_pages; +} + +static unsigned long get_freelist_nr_pages(void) +{ + unsigned long nr_pages; + unsigned long flags; + + spin_lock_irqsave(&free_list_lock, flags); + nr_pages = list_nr_pages; + spin_unlock_irqrestore(&free_list_lock, flags); + return nr_pages; +} + +static unsigned long freelist_shrink_count(struct shrinker *shrinker, + struct shrink_control *sc) +{ + return get_freelist_nr_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_nr_pages() > 0); + + free_one_item(DF_NORMAL); + } + + return 0; +} + +static int deferred_freelist_init(void) +{ + list_nr_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..11940328ce3f --- /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. + * + * @nr_pages: number of pages used by 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 nr_pages; + 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 + * @nr_pages: number of pages to be freed + */ +void deferred_free(struct deferred_freelist_item *item, + void (*free)(struct deferred_freelist_item *i, + enum df_reason reason), + size_t nr_pages); +#endif