From patchwork Mon Mar 31 20:16:57 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Tvrtko Ursulin X-Patchwork-Id: 14034088 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 39FB8C36016 for ; Mon, 31 Mar 2025 20:17:44 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 4A05410E490; Mon, 31 Mar 2025 20:17:42 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=igalia.com header.i=@igalia.com header.b="nRJ6uBs4"; dkim-atps=neutral Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by gabe.freedesktop.org (Postfix) with ESMTPS id 35A6B10E486; Mon, 31 Mar 2025 20:17:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:MIME-Version:References: In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=tB9H8yMWyZh2iV+fD5BHTBYtLY0SpJOAUqAv2XGh5xw=; b=nRJ6uBs423KgUFG73uhHtDcyFu GAnP/yaXzDukgMCM69ExXawKO/AFQVV7HKSUMyFSyFAx2Pp78iAsZvqA4hBFZkTdeW44dWF/svLQi fQ1gcytgOWN7doQYwLGvL275iYPaMK7MXHUy2rdH/IUP6WB/UZR7QVGdqQK371s2ZegpQ4IexOeji u25cOEvO8FFqLq3NZDrQNP6WVDy2F6KAf9Cp4PGWERY0foEGf0TjviTAqo20/i94WlWl6R/cwO4iB CBpleBOrjZhst5d+2e7frBtt2JcfbMk+mS/ribDj1Hf+DZBXrfr8i2uAe9UQKzEnWPSsmDBfpAIKn KF3UaxoA==; Received: from [90.241.98.187] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1tzLZa-009M3G-Fh; Mon, 31 Mar 2025 22:17:30 +0200 From: Tvrtko Ursulin To: amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Cc: kernel-dev@igalia.com, Tvrtko Ursulin , =?utf-8?q?Christian_K=C3=B6nig?= , Danilo Krummrich , Matthew Brost , Philipp Stanner Subject: [RFC v3 06/14] drm/sched: Implement RR via FIFO Date: Mon, 31 Mar 2025 21:16:57 +0100 Message-ID: <20250331201705.60663-7-tvrtko.ursulin@igalia.com> X-Mailer: git-send-email 2.48.0 In-Reply-To: <20250331201705.60663-1-tvrtko.ursulin@igalia.com> References: <20250331201705.60663-1-tvrtko.ursulin@igalia.com> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Round-robin being the non-default policy and unclear how much it is used, we can notice that it can be implemented using the FIFO data structures if we only invent a fake submit timestamp which is monotonically increasing inside drm_sched_rq instances. So instead of remembering which was the last entity the scheduler worker picked, we can bump the picked one to the bottom of the tree, achieving the same round-robin behaviour. Advantage is that we can consolidate to a single code path and remove a bunch of code. Downside is round-robin mode now needs to lock on the job pop path but that should not be visible. Signed-off-by: Tvrtko Ursulin Cc: Christian König Cc: Danilo Krummrich Cc: Matthew Brost Cc: Philipp Stanner --- drivers/gpu/drm/scheduler/sched_entity.c | 45 ++++++++------ drivers/gpu/drm/scheduler/sched_main.c | 76 ++---------------------- include/drm/gpu_scheduler.h | 5 +- 3 files changed, 36 insertions(+), 90 deletions(-) diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c index 9b0122e99b44..bbb7f3d3e3e8 100644 --- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -469,9 +469,19 @@ drm_sched_job_dependency(struct drm_sched_job *job, return NULL; } +static ktime_t +drm_sched_rq_get_rr_deadline(struct drm_sched_rq *rq) +{ + lockdep_assert_held(&rq->lock); + + rq->rr_deadline = ktime_add_ns(rq->rr_deadline, 1); + + return rq->rr_deadline; +} + struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity) { - struct drm_sched_job *sched_job; + struct drm_sched_job *sched_job, *next_job; sched_job = drm_sched_entity_queue_peek(entity); if (!sched_job) @@ -506,21 +516,22 @@ struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity) * Update the entity's location in the min heap according to * the timestamp of the next job, if any. */ - if (drm_sched_policy == DRM_SCHED_POLICY_FIFO) { - struct drm_sched_job *next; + next_job = drm_sched_entity_queue_peek(entity); + if (next_job) { + struct drm_sched_rq *rq; + ktime_t ts; - next = drm_sched_entity_queue_peek(entity); - if (next) { - struct drm_sched_rq *rq; + if (drm_sched_policy == DRM_SCHED_POLICY_FIFO) + ts = next_job->submit_ts; + else + ts = drm_sched_rq_get_rr_deadline(rq); - spin_lock(&entity->lock); - rq = entity->rq; - spin_lock(&rq->lock); - drm_sched_rq_update_fifo_locked(entity, rq, - next->submit_ts); - spin_unlock(&rq->lock); - spin_unlock(&entity->lock); - } + spin_lock(&entity->lock); + rq = entity->rq; + spin_lock(&rq->lock); + drm_sched_rq_update_fifo_locked(entity, rq, ts); + spin_unlock(&rq->lock); + spin_unlock(&entity->lock); } /* Jobs and entities might have different lifecycles. Since we're @@ -619,9 +630,9 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job) spin_lock(&rq->lock); drm_sched_rq_add_entity(rq, entity); - - if (drm_sched_policy == DRM_SCHED_POLICY_FIFO) - drm_sched_rq_update_fifo_locked(entity, rq, submit_ts); + if (drm_sched_policy == DRM_SCHED_POLICY_RR) + submit_ts = drm_sched_rq_get_rr_deadline(rq); + drm_sched_rq_update_fifo_locked(entity, rq, submit_ts); spin_unlock(&rq->lock); spin_unlock(&entity->lock); diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c index 600904271b01..e931a9b91083 100644 --- a/drivers/gpu/drm/scheduler/sched_main.c +++ b/drivers/gpu/drm/scheduler/sched_main.c @@ -190,7 +190,6 @@ static void drm_sched_rq_init(struct drm_gpu_scheduler *sched, spin_lock_init(&rq->lock); INIT_LIST_HEAD(&rq->entities); rq->rb_tree_root = RB_ROOT_CACHED; - rq->current_entity = NULL; rq->sched = sched; } @@ -236,74 +235,13 @@ void drm_sched_rq_remove_entity(struct drm_sched_rq *rq, atomic_dec(rq->sched->score); list_del_init(&entity->list); - if (rq->current_entity == entity) - rq->current_entity = NULL; - - if (drm_sched_policy == DRM_SCHED_POLICY_FIFO) - drm_sched_rq_remove_fifo_locked(entity, rq); + drm_sched_rq_remove_fifo_locked(entity, rq); spin_unlock(&rq->lock); } /** - * drm_sched_rq_select_entity_rr - Select an entity which could provide a job to run - * - * @sched: the gpu scheduler - * @rq: scheduler run queue to check. - * - * Try to find the next ready entity. - * - * Return an entity if one is found; return an error-pointer (!NULL) if an - * entity was ready, but the scheduler had insufficient credits to accommodate - * its job; return NULL, if no ready entity was found. - */ -static struct drm_sched_entity * -drm_sched_rq_select_entity_rr(struct drm_gpu_scheduler *sched, - struct drm_sched_rq *rq) -{ - struct drm_sched_entity *entity; - - spin_lock(&rq->lock); - - entity = rq->current_entity; - if (entity) { - list_for_each_entry_continue(entity, &rq->entities, list) { - if (drm_sched_entity_is_ready(entity)) - goto found; - } - } - - list_for_each_entry(entity, &rq->entities, list) { - if (drm_sched_entity_is_ready(entity)) - goto found; - - if (entity == rq->current_entity) - break; - } - - spin_unlock(&rq->lock); - - return NULL; - -found: - if (!drm_sched_can_queue(sched, entity)) { - /* - * If scheduler cannot take more jobs signal the caller to not - * consider lower priority queues. - */ - entity = ERR_PTR(-ENOSPC); - } else { - rq->current_entity = entity; - reinit_completion(&entity->entity_idle); - } - - spin_unlock(&rq->lock); - - return entity; -} - -/** - * drm_sched_rq_select_entity_fifo - Select an entity which provides a job to run + * drm_sched_rq_select_entity - Select an entity which provides a job to run * * @sched: the gpu scheduler * @rq: scheduler run queue to check. @@ -315,8 +253,8 @@ drm_sched_rq_select_entity_rr(struct drm_gpu_scheduler *sched, * its job; return NULL, if no ready entity was found. */ static struct drm_sched_entity * -drm_sched_rq_select_entity_fifo(struct drm_gpu_scheduler *sched, - struct drm_sched_rq *rq) +drm_sched_rq_select_entity(struct drm_gpu_scheduler *sched, + struct drm_sched_rq *rq) { struct drm_sched_entity *entity = NULL; struct rb_node *rb; @@ -1061,15 +999,13 @@ void drm_sched_wakeup(struct drm_gpu_scheduler *sched) static struct drm_sched_entity * drm_sched_select_entity(struct drm_gpu_scheduler *sched) { - struct drm_sched_entity *entity; + struct drm_sched_entity *entity = NULL; int i; /* Start with the highest priority. */ for (i = DRM_SCHED_PRIORITY_KERNEL; i < sched->num_rqs; i++) { - entity = drm_sched_policy == DRM_SCHED_POLICY_FIFO ? - drm_sched_rq_select_entity_fifo(sched, sched->sched_rq[i]) : - drm_sched_rq_select_entity_rr(sched, sched->sched_rq[i]); + entity = drm_sched_rq_select_entity(sched, sched->sched_rq[i]); if (entity) break; } diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h index 1a7e377d4cbb..1073cc569cce 100644 --- a/include/drm/gpu_scheduler.h +++ b/include/drm/gpu_scheduler.h @@ -239,8 +239,7 @@ struct drm_sched_entity { * struct drm_sched_rq - queue of entities to be scheduled. * * @sched: the scheduler to which this rq belongs to. - * @lock: protects @entities, @rb_tree_root and @current_entity. - * @current_entity: the entity which is to be scheduled. + * @lock: protects @entities, @rb_tree_root and @rr_deadline. * @entities: list of the entities to be scheduled. * @rb_tree_root: root of time based priority queue of entities for FIFO scheduling * @@ -253,7 +252,7 @@ struct drm_sched_rq { spinlock_t lock; /* Following members are protected by the @lock: */ - struct drm_sched_entity *current_entity; + ktime_t rr_deadline; struct list_head entities; struct rb_root_cached rb_tree_root; };