From patchwork Tue Aug 2 15:51:42 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Rob Clark X-Patchwork-Id: 12934832 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D07EC00140 for ; Tue, 2 Aug 2022 15:52:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237550AbiHBPwM (ORCPT ); Tue, 2 Aug 2022 11:52:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54744 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237467AbiHBPvx (ORCPT ); Tue, 2 Aug 2022 11:51:53 -0400 Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0DAB83CBE7; Tue, 2 Aug 2022 08:51:43 -0700 (PDT) Received: by mail-pj1-x102d.google.com with SMTP id q7-20020a17090a7a8700b001f300db8677so15753988pjf.5; Tue, 02 Aug 2022 08:51:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc; bh=Le752qOQHMV5YKNomZZhvKAccL9F4fI/bs+OgheaM0E=; b=ZNmkoFJQCUZt/2K96EzfkPzt9hq2E2EaSqg5Iw2fag3s0eYQQMl++JyuKjbMEiSDF5 nIHWuSk1zkzgQmlVeTromJairAKWW1CiLdtYFo9LSsi66uYoD9Oiq35ycvhOYrqdiNn4 US2PAzSSj3mjIrO585M5l5pkEIrd9DEiewZ8hn7SxBh0DJueyu2+w4rPwRRH1COp1AGC yl2nX3cVFnmYta09Sdp0KeoCr7G/C+6cVMY5Z4/R+ljdwmRGQfisKAuLJm6sORDzTwW1 67G/r6ywbgOz7sv1sso5TdI6BJaqhfdfozKHr7O4cVXyLoNwRr7KQ6U99AOBJQnL1Mu6 C3Ag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc; bh=Le752qOQHMV5YKNomZZhvKAccL9F4fI/bs+OgheaM0E=; b=1LHnYP+bBEMF9tEJClnTmKZmAxzEUoAObQSDom8Vb3w6HRadBcnmHexVvszyhcE4en QapUEFVNzI4cCNoFQ0v1u5nE8oHWB6d/tQWLvp3EGawjPIF55K71Qb+hDn8Z3UFrvjjH kHQhmqAg6PjWjcT8K7kK0OswAQMGnKdq7yva31hH2LZTPlsEAPUleUL6BMauDWAWq4Id y5mWwohEd8kD3VLc++Ix2T9C7ynRYJI6JJQ5xIr8OoYzxqh38qjiGKTdk7oAtdRPIxzY hUfBhhWjmJbnGQj1BZCdIHdE78MG2/WEdn6lSitn7p/G0ai4oKNkwJi79quR9hxGDNUZ bS6g== X-Gm-Message-State: ACgBeo0Ywxx5B3K4p4BjR45KTuWVEpj8t771bR2j+6pGWel5kk92LkjC 19f7IlfqBKudyFDXaJ7nZdMAVdEOc3w= X-Google-Smtp-Source: AA6agR5ifOOl6novGltLYp/+Nqhh+R7D/QWeM2OiTe0tVonfWJscREiz+fHcPxqwBLzSs5IbjVsN8g== X-Received: by 2002:a17:90b:4d8e:b0:1f3:160e:1a5c with SMTP id oj14-20020a17090b4d8e00b001f3160e1a5cmr155031pjb.10.1659455502353; Tue, 02 Aug 2022 08:51:42 -0700 (PDT) Received: from localhost ([2a00:79e1:abd:4a00:2703:3c72:eb1a:cffd]) by smtp.gmail.com with ESMTPSA id a15-20020a170902710f00b0016d9468bb20sm11920276pll.129.2022.08.02.08.51.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Aug 2022 08:51:41 -0700 (PDT) From: Rob Clark To: dri-devel@lists.freedesktop.org Cc: freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, Rob Clark , Daniel Vetter , Thomas Zimmermann , Dmitry Osipenko , Maarten Lankhorst , Maxime Ripard , David Airlie , linux-kernel@vger.kernel.org (open list) Subject: [PATCH v4 09/15] drm/gem: Add LRU/shrinker helper Date: Tue, 2 Aug 2022 08:51:42 -0700 Message-Id: <20220802155152.1727594-10-robdclark@gmail.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220802155152.1727594-1-robdclark@gmail.com> References: <20220802155152.1727594-1-robdclark@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org From: Rob Clark Add a simple LRU helper to assist with driver's shrinker implementation. It handles tracking the number of backing pages associated with a given LRU, and provides a helper to implement shrinker_scan. A driver can use multiple LRU instances to track objects in various states, for example a dontneed LRU for purgeable objects, a willneed LRU for evictable objects, and an unpinned LRU for objects without backing pages. All LRUs that the object can be moved between must share a single lock. v2: lockdep_assert_held() instead of WARN_ON(!mutex_is_locked()) v3: make drm_gem_lru_move_tail_locked() static until there is a user Cc: Daniel Vetter Cc: Thomas Zimmermann Cc: Dmitry Osipenko Signed-off-by: Rob Clark Reviewed-by: Dmitry Osipenko --- drivers/gpu/drm/drm_gem.c | 170 ++++++++++++++++++++++++++++++++++++++ include/drm/drm_gem.h | 55 ++++++++++++ 2 files changed, 225 insertions(+) diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index eb0c2d041f13..556714c10472 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -165,6 +165,7 @@ void drm_gem_private_object_init(struct drm_device *dev, obj->resv = &obj->_resv; drm_vma_node_reset(&obj->vma_node); + INIT_LIST_HEAD(&obj->lru_node); } EXPORT_SYMBOL(drm_gem_private_object_init); @@ -951,6 +952,7 @@ drm_gem_object_release(struct drm_gem_object *obj) dma_resv_fini(&obj->_resv); drm_gem_free_mmap_offset(obj); + drm_gem_lru_remove(obj); } EXPORT_SYMBOL(drm_gem_object_release); @@ -1274,3 +1276,171 @@ drm_gem_unlock_reservations(struct drm_gem_object **objs, int count, ww_acquire_fini(acquire_ctx); } EXPORT_SYMBOL(drm_gem_unlock_reservations); + +/** + * drm_gem_lru_init - initialize a LRU + * + * @lru: The LRU to initialize + * @lock: The lock protecting the LRU + */ +void +drm_gem_lru_init(struct drm_gem_lru *lru, struct mutex *lock) +{ + lru->lock = lock; + lru->count = 0; + INIT_LIST_HEAD(&lru->list); +} +EXPORT_SYMBOL(drm_gem_lru_init); + +static void +drm_gem_lru_remove_locked(struct drm_gem_object *obj) +{ + obj->lru->count -= obj->size >> PAGE_SHIFT; + WARN_ON(obj->lru->count < 0); + list_del(&obj->lru_node); + obj->lru = NULL; +} + +/** + * drm_gem_lru_remove - remove object from whatever LRU it is in + * + * If the object is currently in any LRU, remove it. + * + * @obj: The GEM object to remove from current LRU + */ +void +drm_gem_lru_remove(struct drm_gem_object *obj) +{ + struct drm_gem_lru *lru = obj->lru; + + if (!lru) + return; + + mutex_lock(lru->lock); + drm_gem_lru_remove_locked(obj); + mutex_unlock(lru->lock); +} +EXPORT_SYMBOL(drm_gem_lru_remove); + +static void +drm_gem_lru_move_tail_locked(struct drm_gem_lru *lru, struct drm_gem_object *obj) +{ + lockdep_assert_held_once(lru->lock); + + if (obj->lru) + drm_gem_lru_remove_locked(obj); + + lru->count += obj->size >> PAGE_SHIFT; + list_add_tail(&obj->lru_node, &lru->list); + obj->lru = lru; +} + +/** + * drm_gem_lru_move_tail - move the object to the tail of the LRU + * + * If the object is already in this LRU it will be moved to the + * tail. Otherwise it will be removed from whichever other LRU + * it is in (if any) and moved into this LRU. + * + * @lru: The LRU to move the object into. + * @obj: The GEM object to move into this LRU + */ +void +drm_gem_lru_move_tail(struct drm_gem_lru *lru, struct drm_gem_object *obj) +{ + mutex_lock(lru->lock); + drm_gem_lru_move_tail_locked(lru, obj); + mutex_unlock(lru->lock); +} +EXPORT_SYMBOL(drm_gem_lru_move_tail); + +/** + * drm_gem_lru_scan - helper to implement shrinker.scan_objects + * + * If the shrink callback succeeds, it is expected that the driver + * move the object out of this LRU. + * + * If the LRU possibly contain active buffers, it is the responsibility + * of the shrink callback to check for this (ie. dma_resv_test_signaled()) + * or if necessary block until the buffer becomes idle. + * + * @lru: The LRU to scan + * @nr_to_scan: The number of pages to try to reclaim + * @shrink: Callback to try to shrink/reclaim the object. + */ +unsigned long +drm_gem_lru_scan(struct drm_gem_lru *lru, unsigned nr_to_scan, + bool (*shrink)(struct drm_gem_object *obj)) +{ + struct drm_gem_lru still_in_lru; + struct drm_gem_object *obj; + unsigned freed = 0; + + drm_gem_lru_init(&still_in_lru, lru->lock); + + mutex_lock(lru->lock); + + while (freed < nr_to_scan) { + obj = list_first_entry_or_null(&lru->list, typeof(*obj), lru_node); + + if (!obj) + break; + + drm_gem_lru_move_tail_locked(&still_in_lru, obj); + + /* + * If it's in the process of being freed, gem_object->free() + * may be blocked on lock waiting to remove it. So just + * skip it. + */ + if (!kref_get_unless_zero(&obj->refcount)) + continue; + + /* + * Now that we own a reference, we can drop the lock for the + * rest of the loop body, to reduce contention with other + * code paths that need the LRU lock + */ + mutex_unlock(lru->lock); + + /* + * Note that this still needs to be trylock, since we can + * hit shrinker in response to trying to get backing pages + * for this obj (ie. while it's lock is already held) + */ + if (!dma_resv_trylock(obj->resv)) + goto tail; + + if (shrink(obj)) { + freed += obj->size >> PAGE_SHIFT; + + /* + * If we succeeded in releasing the object's backing + * pages, we expect the driver to have moved the object + * out of this LRU + */ + WARN_ON(obj->lru == &still_in_lru); + WARN_ON(obj->lru == lru); + } + + dma_resv_unlock(obj->resv); + +tail: + drm_gem_object_put(obj); + mutex_lock(lru->lock); + } + + /* + * Move objects we've skipped over out of the temporary still_in_lru + * back into this LRU + */ + list_for_each_entry (obj, &still_in_lru.list, lru_node) + obj->lru = lru; + list_splice_tail(&still_in_lru.list, &lru->list); + lru->count += still_in_lru.count; + + mutex_unlock(lru->lock); + + return freed; +} +EXPORT_SYMBOL(drm_gem_lru_scan); diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index 87cffc9efa85..f28a48a6f846 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -174,6 +174,41 @@ struct drm_gem_object_funcs { const struct vm_operations_struct *vm_ops; }; +/** + * struct drm_gem_lru - A simple LRU helper + * + * A helper for tracking GEM objects in a given state, to aid in + * driver's shrinker implementation. Tracks the count of pages + * for lockless &shrinker.count_objects, and provides + * &drm_gem_lru_scan for driver's &shrinker.scan_objects + * implementation. + */ +struct drm_gem_lru { + /** + * @lock: + * + * Lock protecting movement of GEM objects between LRUs. All + * LRUs that the object can move between should be protected + * by the same lock. + */ + struct mutex *lock; + + /** + * @count: + * + * The total number of backing pages of the GEM objects in + * this LRU. + */ + long count; + + /** + * @list: + * + * The LRU list. + */ + struct list_head list; +}; + /** * struct drm_gem_object - GEM buffer object * @@ -312,6 +347,20 @@ struct drm_gem_object { * */ const struct drm_gem_object_funcs *funcs; + + /** + * @lru_node: + * + * List node in a &drm_gem_lru. + */ + struct list_head lru_node; + + /** + * @lru: + * + * The current LRU list that the GEM object is on. + */ + struct drm_gem_lru *lru; }; /** @@ -420,4 +469,10 @@ void drm_gem_unlock_reservations(struct drm_gem_object **objs, int count, int drm_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev, u32 handle, u64 *offset); +void drm_gem_lru_init(struct drm_gem_lru *lru, struct mutex *lock); +void drm_gem_lru_remove(struct drm_gem_object *obj); +void drm_gem_lru_move_tail(struct drm_gem_lru *lru, struct drm_gem_object *obj); +unsigned long drm_gem_lru_scan(struct drm_gem_lru *lru, unsigned nr_to_scan, + bool (*shrink)(struct drm_gem_object *obj)); + #endif /* __DRM_GEM_H__ */