From patchwork Mon Feb 4 13:22:13 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 10795605 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C1A101805 for ; Mon, 4 Feb 2019 13:22:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B07E22B497 for ; Mon, 4 Feb 2019 13:22:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A4F602B498; Mon, 4 Feb 2019 13:22:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 0BA922B49A for ; Mon, 4 Feb 2019 13:22:48 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id BAFF16E4DF; Mon, 4 Feb 2019 13:22:44 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1509C6E4DD for ; Mon, 4 Feb 2019 13:22:42 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from haswell.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 15458874-1500050 for multiple; Mon, 04 Feb 2019 13:22:27 +0000 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Mon, 4 Feb 2019 13:22:13 +0000 Message-Id: <20190204132214.9459-22-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190204132214.9459-1-chris@chris-wilson.co.uk> References: <20190204132214.9459-1-chris@chris-wilson.co.uk> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 21/22] drm/i915: Prioritise non-busywait semaphore workloads X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP We don't want to busywait on the GPU if we have other work to do. If we give non-busywaiting workloads higher (initial) priority than workloads that require a busywait, we will prioritise work that is ready to run immediately. We then also have to be careful that we don't give earlier semaphores an accidental boost because later work doesn't wait on other rings, hence we keep a history of semaphore usage of the dependency chain. Testcase: igt/gem_exec_schedule/semaphore Signed-off-by: Chris Wilson --- drivers/gpu/drm/i915/i915_request.c | 16 ++++++++++++++++ drivers/gpu/drm/i915/i915_scheduler.c | 10 ++++++++++ drivers/gpu/drm/i915/i915_scheduler.h | 9 ++++++--- drivers/gpu/drm/i915/intel_lrc.c | 2 +- 4 files changed, 33 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 116bd9648db7..91dcaf07958f 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -832,6 +832,7 @@ emit_semaphore_wait(struct i915_request *to, *cs++ = 0; intel_ring_advance(to, cs); + to->sched.semaphore |= I915_SCHED_HAS_SEMAPHORE; return 0; } @@ -1102,6 +1103,21 @@ void i915_request_add(struct i915_request *request) if (engine->schedule) { struct i915_sched_attr attr = request->gem_context->sched; + /* + * Boost actual workloads past semaphores! + * + * With semaphores we spin on one engine waiting for another, + * simply to reduce the latency of starting our work when + * the signaler completes. However, if there is any other + * work that we could be doing on this engine instead, that + * is better utilisation and will reduce the overall duration + * of the current work. To avoid PI boosting a semaphore + * far in the distance past over useful work, we keep a history + * of any semaphore use along our dependency chain. + */ + if (!request->sched.semaphore) + attr.priority |= I915_PRIORITY_NOSEMAPHORE; + /* * Boost priorities to new clients (new request flows). * diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c index 7c1d9ef98374..9675ead24f75 100644 --- a/drivers/gpu/drm/i915/i915_scheduler.c +++ b/drivers/gpu/drm/i915/i915_scheduler.c @@ -28,12 +28,18 @@ static inline bool node_signaled(const struct i915_sched_node *node) return i915_request_completed(node_to_request(node)); } +static inline bool node_started(const struct i915_sched_node *node) +{ + return i915_request_started(node_to_request(node)); +} + void i915_sched_node_init(struct i915_sched_node *node) { INIT_LIST_HEAD(&node->signalers_list); INIT_LIST_HEAD(&node->waiters_list); INIT_LIST_HEAD(&node->link); node->attr.priority = I915_PRIORITY_INVALID; + node->semaphore = 0; } static struct i915_dependency * @@ -64,6 +70,10 @@ bool __i915_sched_node_add_dependency(struct i915_sched_node *node, dep->signaler = signal; dep->flags = flags; + /* Keep track of whether anyone on this chain has a semaphore */ + if (signal->semaphore && !node_started(signal)) + node->semaphore |= signal->semaphore << 1; + ret = true; } diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h index 5196ce07b6c2..24c2c027fd2c 100644 --- a/drivers/gpu/drm/i915/i915_scheduler.h +++ b/drivers/gpu/drm/i915/i915_scheduler.h @@ -24,14 +24,15 @@ enum { I915_PRIORITY_INVALID = INT_MIN }; -#define I915_USER_PRIORITY_SHIFT 2 +#define I915_USER_PRIORITY_SHIFT 3 #define I915_USER_PRIORITY(x) ((x) << I915_USER_PRIORITY_SHIFT) #define I915_PRIORITY_COUNT BIT(I915_USER_PRIORITY_SHIFT) #define I915_PRIORITY_MASK (I915_PRIORITY_COUNT - 1) -#define I915_PRIORITY_WAIT ((u8)BIT(0)) -#define I915_PRIORITY_NEWCLIENT ((u8)BIT(1)) +#define I915_PRIORITY_WAIT ((u8)BIT(0)) +#define I915_PRIORITY_NEWCLIENT ((u8)BIT(1)) +#define I915_PRIORITY_NOSEMAPHORE ((u8)BIT(2)) #define __NO_PREEMPTION (I915_PRIORITY_WAIT) @@ -74,6 +75,8 @@ struct i915_sched_node { struct list_head waiters_list; /* those after us, they depend upon us */ struct list_head link; struct i915_sched_attr attr; + unsigned long semaphore; +#define I915_SCHED_HAS_SEMAPHORE BIT(0) }; struct i915_dependency { diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index ea813f88fbb3..ae90ce034252 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -164,7 +164,7 @@ #define WA_TAIL_DWORDS 2 #define WA_TAIL_BYTES (sizeof(u32) * WA_TAIL_DWORDS) -#define ACTIVE_PRIORITY (I915_PRIORITY_NEWCLIENT) +#define ACTIVE_PRIORITY (I915_PRIORITY_NEWCLIENT | I915_PRIORITY_NOSEMAPHORE) static int execlists_context_deferred_alloc(struct i915_gem_context *ctx, struct intel_engine_cs *engine,