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From: Chris Wilson <chris@chris-wilson.co.uk>
To: intel-gfx@lists.freedesktop.org
Cc: mika.kuoppala@intel.com
Subject: [PATCH 35/38] drm/i915: Reserve space in the global seqno during request allocation
Date: Tue, 20 Sep 2016 09:30:09 +0100	[thread overview]
Message-ID: <20160920083012.2754-36-chris@chris-wilson.co.uk> (raw)
In-Reply-To: <20160920083012.2754-1-chris@chris-wilson.co.uk>

A restriction on our global seqno is that they cannot wrap, and that we
cannot use the value 0. This allows us to detect when a request has not
yet been submitted, its global seqno is still 0, and ensures that
hardware semaphores are monotonic as required by older hardware. To
meet these restrictions when we defer the assignment of the global
seqno, we must check that we have an available slot in the global seqno
space during request construction. If that test fails, we wait for all
requests to be completed and reset the hardware back to 0.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com
---
 drivers/gpu/drm/i915/i915_debugfs.c      | 10 ++--
 drivers/gpu/drm/i915/i915_drv.h          |  2 +-
 drivers/gpu/drm/i915/i915_gem.c          |  7 ++-
 drivers/gpu/drm/i915/i915_gem_request.c  | 83 ++++++++++++++++----------------
 drivers/gpu/drm/i915/i915_gem_timeline.h |  2 +-
 5 files changed, 51 insertions(+), 53 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index ca7d2e0da23c..de09b7fefde2 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -579,7 +579,7 @@ static int i915_gem_pageflip_info(struct seq_file *m, void *data)
 				seq_printf(m, "Flip queued on %s at seqno %x, next seqno %x [current breadcrumb %x], completed? %d\n",
 					   engine->name,
 					   i915_gem_request_get_seqno(work->flip_queued_req),
-					   dev_priv->gt.global_timeline.next_seqno,
+					   atomic_read(&dev_priv->gt.global_timeline.next_seqno),
 					   intel_engine_get_seqno(engine),
 					   i915_gem_request_completed(work->flip_queued_req));
 			} else
@@ -1055,7 +1055,7 @@ i915_next_seqno_get(void *data, u64 *val)
 {
 	struct drm_i915_private *dev_priv = data;
 
-	*val = READ_ONCE(dev_priv->gt.global_timeline.next_seqno);
+	*val = atomic_read(&dev_priv->gt.global_timeline.next_seqno);
 	return 0;
 }
 
@@ -2331,8 +2331,8 @@ static int i915_rps_boost_info(struct seq_file *m, void *data)
 	struct drm_file *file;
 
 	seq_printf(m, "RPS enabled? %d\n", dev_priv->rps.enabled);
-	seq_printf(m, "GPU busy? %s [%x]\n",
-		   yesno(dev_priv->gt.awake), dev_priv->gt.active_engines);
+	seq_printf(m, "GPU busy? %s [%d requests]\n",
+		   yesno(dev_priv->gt.awake), dev_priv->gt.active_requests);
 	seq_printf(m, "CPU waiting? %d\n", count_irq_waiters(dev_priv));
 	seq_printf(m, "Frequency requested %d\n",
 		   intel_gpu_freq(dev_priv, dev_priv->rps.cur_freq));
@@ -2367,7 +2367,7 @@ static int i915_rps_boost_info(struct seq_file *m, void *data)
 
 	if (INTEL_GEN(dev_priv) >= 6 &&
 	    dev_priv->rps.enabled &&
-	    dev_priv->gt.active_engines) {
+	    dev_priv->gt.active_requests) {
 		u32 rpup, rpupei;
 		u32 rpdown, rpdownei;
 
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index bb2b8b41eb61..48c63365184d 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2059,6 +2059,7 @@ struct drm_i915_private {
 
 		struct list_head timelines;
 		struct i915_gem_timeline global_timeline;
+		u32 active_requests;
 
 		/**
 		 * Is the GPU currently considered idle, or busy executing
@@ -2067,7 +2068,6 @@ struct drm_i915_private {
 		 * In order to reduce the effect on performance, there
 		 * is a slight delay before we do so.
 		 */
-		unsigned int active_engines;
 		bool awake;
 
 		/**
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 659ee3b910d7..cd436f28e702 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2640,8 +2640,6 @@ static void i915_gem_cleanup_engine(struct intel_engine_cs *engine)
 		memset(engine->execlist_port, 0, sizeof(engine->execlist_port));
 		spin_unlock(&engine->execlist_lock);
 	}
-
-	engine->i915->gt.active_engines &= ~intel_engine_flag(engine);
 }
 
 void i915_gem_set_wedged(struct drm_i915_private *dev_priv)
@@ -2696,7 +2694,7 @@ i915_gem_idle_work_handler(struct work_struct *work)
 	if (!READ_ONCE(dev_priv->gt.awake))
 		return;
 
-	if (READ_ONCE(dev_priv->gt.active_engines))
+	if (READ_ONCE(dev_priv->gt.active_requests))
 		return;
 
 	rearm_hangcheck =
@@ -2710,7 +2708,7 @@ i915_gem_idle_work_handler(struct work_struct *work)
 		goto out_rearm;
 	}
 
-	if (dev_priv->gt.active_engines)
+	if (dev_priv->gt.active_requests)
 		goto out_unlock;
 
 	for_each_engine(engine, dev_priv)
@@ -4298,6 +4296,7 @@ int i915_gem_suspend(struct drm_device *dev)
 		goto err;
 
 	i915_gem_retire_requests(dev_priv);
+	GEM_BUG_ON(dev_priv->gt.active_requests);
 
 	GEM_BUG_ON(!is_kernel_context(dev_priv));
 	i915_gem_context_lost(dev_priv);
diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 3d09301f7b40..7234540522bd 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -156,6 +156,7 @@ static void i915_gem_request_retire(struct drm_i915_gem_request *request)
 	 */
 	list_del(&request->ring_link);
 	request->ring->last_retired_head = request->postfix;
+	request->i915->gt.active_requests--;
 
 	/* Walk through the active list, calling retire on each. This allows
 	 * objects to track their GPU activity and mark themselves as idle
@@ -252,12 +253,13 @@ static int i915_gem_init_global_seqno(struct drm_i915_private *dev_priv,
 	i915_gem_retire_requests(dev_priv);
 
 	/* If the seqno wraps around, we need to clear the breadcrumb rbtree */
-	if (!i915_seqno_passed(seqno,
-			       dev_priv->gt.global_timeline.next_seqno)) {
+	timeline = &dev_priv->gt.global_timeline;;
+	if (!i915_seqno_passed(seqno, atomic_read(&timeline->next_seqno))) {
 		while (intel_kick_waiters(dev_priv) ||
 		       intel_kick_signalers(dev_priv))
 			yield();
 	}
+	atomic_set(&timeline->next_seqno, seqno);
 
 	/* Finally reset hw state */
 	for_each_engine(engine, dev_priv)
@@ -277,7 +279,6 @@ static int i915_gem_init_global_seqno(struct drm_i915_private *dev_priv,
 int i915_gem_set_global_seqno(struct drm_device *dev, u32 seqno)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
-	int ret;
 
 	lockdep_assert_held(&dev_priv->drm.struct_mutex);
 
@@ -287,34 +288,33 @@ int i915_gem_set_global_seqno(struct drm_device *dev, u32 seqno)
 	/* HWS page needs to be set less than what we
 	 * will inject to ring
 	 */
-	ret = i915_gem_init_global_seqno(dev_priv, seqno - 1);
-	if (ret)
-		return ret;
-
-	dev_priv->gt.global_timeline.next_seqno = seqno;
-	return 0;
+	return i915_gem_init_global_seqno(dev_priv, seqno - 1);
 }
 
-static int i915_gem_get_global_seqno(struct drm_i915_private *dev_priv,
-				     u32 *seqno)
+static int reserve_global_seqno(struct drm_i915_private *i915)
 {
-	struct i915_gem_timeline *tl = &dev_priv->gt.global_timeline;
-
-	/* reserve 0 for non-seqno */
-	if (unlikely(tl->next_seqno == 0)) {
-		int ret;
+	u32 active_requests = ++i915->gt.active_requests;
+	u32 next_seqno = atomic_read(&i915->gt.global_timeline.next_seqno);
+	int ret;
 
-		ret = i915_gem_init_global_seqno(dev_priv, 0);
-		if (ret)
-			return ret;
+	/* Reservation is fine until we need to wrap around */
+	if (likely(next_seqno + active_requests > next_seqno))
+		return 0;
 
-		tl->next_seqno = 1;
+	ret = i915_gem_init_global_seqno(i915, 0);
+	if (ret) {
+		i915->gt.active_requests--;
+		return ret;
 	}
 
-	*seqno = tl->next_seqno++;
 	return 0;
 }
 
+static u32 timeline_get_seqno(struct i915_gem_timeline *tl)
+{
+	return atomic_inc_return(&tl->next_seqno);
+}
+
 static int __i915_sw_fence_call
 submit_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
 {
@@ -353,9 +353,10 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
 {
 	struct drm_i915_private *dev_priv = engine->i915;
 	struct drm_i915_gem_request *req;
-	u32 seqno;
 	int ret;
 
+	lockdep_assert_held(&dev_priv->drm.struct_mutex);
+
 	/* ABI: Before userspace accesses the GPU (e.g. execbuffer), report
 	 * EIO if the GPU is already wedged, or EAGAIN to drop the struct_mutex
 	 * and restart.
@@ -364,6 +365,10 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
 	if (ret)
 		return ERR_PTR(ret);
 
+	ret = reserve_global_seqno(dev_priv);
+	if (ret)
+		return ERR_PTR(ret);
+
 	/* Move the oldest request to the slab-cache (if not in use!) */
 	req = list_first_entry_or_null(&engine->timeline->requests,
 				       typeof(*req), link);
@@ -399,12 +404,10 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
 	 * Do not use kmem_cache_zalloc() here!
 	 */
 	req = kmem_cache_alloc(dev_priv->requests, GFP_KERNEL);
-	if (!req)
-		return ERR_PTR(-ENOMEM);
-
-	ret = i915_gem_get_global_seqno(dev_priv, &seqno);
-	if (ret)
-		goto err;
+	if (!req) {
+		ret = -ENOMEM;
+		goto err_unreserve;
+	}
 
 	req->timeline = engine->timeline;
 
@@ -413,14 +416,14 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
 		   &i915_fence_ops,
 		   &req->lock,
 		   req->timeline->fence_context,
-		   seqno);
+		   timeline_get_seqno(req->timeline->common));
 
 	i915_sw_fence_init(&req->submit, submit_notify);
 
 	INIT_LIST_HEAD(&req->active_list);
 	req->i915 = dev_priv;
 	req->engine = engine;
-	req->global_seqno = seqno;
+	req->global_seqno = req->fence.seqno;
 	req->ctx = i915_gem_context_get(ctx);
 
 	/* No zalloc, must clear what we need by hand */
@@ -456,8 +459,9 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
 
 err_ctx:
 	i915_gem_context_put(ctx);
-err:
 	kmem_cache_free(dev_priv->requests, req);
+err_unreserve:
+	dev_priv->gt.active_requests--;
 	return ERR_PTR(ret);
 }
 
@@ -612,7 +616,6 @@ static void i915_gem_mark_busy(const struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
 
-	dev_priv->gt.active_engines |= intel_engine_flag(engine);
 	if (dev_priv->gt.awake)
 		return;
 
@@ -941,38 +944,34 @@ complete:
 	return timeout;
 }
 
-static bool engine_retire_requests(struct intel_engine_cs *engine)
+static void engine_retire_requests(struct intel_engine_cs *engine)
 {
 	struct drm_i915_gem_request *request, *next;
 
 	list_for_each_entry_safe(request, next,
 				 &engine->timeline->requests, link) {
 		if (!__i915_gem_request_completed(request))
-			return false;
+			return;
 
 		i915_gem_request_retire(request);
 	}
-
-	return true;
 }
 
 void i915_gem_retire_requests(struct drm_i915_private *dev_priv)
 {
 	struct intel_engine_cs *engine;
-	unsigned int tmp;
 
 	lockdep_assert_held(&dev_priv->drm.struct_mutex);
 
-	if (dev_priv->gt.active_engines == 0)
+	if (!dev_priv->gt.active_requests)
 		return;
 
 	GEM_BUG_ON(!dev_priv->gt.awake);
 
-	for_each_engine_masked(engine, dev_priv, dev_priv->gt.active_engines, tmp)
-		if (engine_retire_requests(engine))
-			dev_priv->gt.active_engines &= ~intel_engine_flag(engine);
+	for_each_engine(engine, dev_priv)
+		engine_retire_requests(engine);
 
-	if (dev_priv->gt.active_engines == 0)
+	if (!dev_priv->gt.active_requests)
 		queue_delayed_work(dev_priv->wq,
 				   &dev_priv->gt.idle_work,
 				   msecs_to_jiffies(100));
diff --git a/drivers/gpu/drm/i915/i915_gem_timeline.h b/drivers/gpu/drm/i915/i915_gem_timeline.h
index ec2e56352c4b..8000c09b1ea9 100644
--- a/drivers/gpu/drm/i915/i915_gem_timeline.h
+++ b/drivers/gpu/drm/i915/i915_gem_timeline.h
@@ -54,7 +54,7 @@ struct intel_timeline {
 
 struct i915_gem_timeline {
 	struct list_head link;
-	u32 next_seqno;
+	atomic_t next_seqno;
 
 	struct drm_i915_private *i915;
 	const char *name;
-- 
2.9.3

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  parent reply	other threads:[~2016-09-20  8:30 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-20  8:29 Multiple timelines, take 2 Chris Wilson
2016-09-20  8:29 ` [PATCH 01/38] drm/i915: Allow disabling error capture Chris Wilson
2016-09-21  6:13   ` Joonas Lahtinen
2016-09-20  8:29 ` [PATCH 02/38] drm/i915: Stop the machine whilst capturing the GPU crash dump Chris Wilson
2016-09-26  8:58   ` Joonas Lahtinen
2016-09-20  8:29 ` [PATCH 03/38] drm/i915: Always use the GTT for error capture Chris Wilson
2016-09-21  7:24   ` Joonas Lahtinen
2016-09-20  8:29 ` [PATCH 04/38] drm/i915: Consolidate error object printing Chris Wilson
2016-09-20  8:29 ` [PATCH 05/38] drm/i915: Compress GPU objects in error state Chris Wilson
2016-09-21  7:55   ` Joonas Lahtinen
2016-09-20  8:29 ` [PATCH 06/38] drm/i915: Support asynchronous waits on struct fence from i915_gem_request Chris Wilson
2016-09-21  8:05   ` Joonas Lahtinen
2016-09-20  8:29 ` [PATCH 07/38] drm/i915: Allow i915_sw_fence_await_sw_fence() to allocate Chris Wilson
2016-09-20  8:29 ` [PATCH 08/38] drm/i915: Rearrange i915_wait_request() accounting with callers Chris Wilson
2016-09-21  8:12   ` Joonas Lahtinen
2016-09-20  8:29 ` [PATCH 09/38] drm/i915: Remove unused i915_gem_active_wait() in favour of _unlocked() Chris Wilson
2016-09-20  8:29 ` [PATCH 10/38] drm/i915: Defer active reference until required Chris Wilson
2016-09-21  8:44   ` Joonas Lahtinen
2016-09-20  8:29 ` [PATCH 11/38] drm/i915: Introduce an internal allocator for disposable private objects Chris Wilson
2016-09-21 11:50   ` Joonas Lahtinen
2016-09-27  9:10     ` Chris Wilson
2016-09-20  8:29 ` [PATCH 12/38] drm/i915: Reuse the active golden render state batch Chris Wilson
2016-09-26  7:24   ` Joonas Lahtinen
2016-09-20  8:29 ` [PATCH 13/38] drm/i915: Markup GEM API with lockdep asserts Chris Wilson
2016-09-21 11:56   ` Joonas Lahtinen
2016-09-20  8:29 ` [PATCH 14/38] drm/i915: Use a radixtree for random access to the object's backing storage Chris Wilson
2016-09-20  8:29 ` [PATCH 15/38] drm/i915: Refactor object page API Chris Wilson
2016-09-20  8:29 ` [PATCH 16/38] drm/i915: Pass around sg_table to get_pages/put_pages backend Chris Wilson
2016-09-20 11:24   ` kbuild test robot
2016-09-20  8:29 ` [PATCH 17/38] drm/i915: Move object backing storage manipulation to its own locking Chris Wilson
2016-09-20  8:29 ` [PATCH 18/38] drm/i915/dmabuf: Acquire the backing storage outside of struct_mutex Chris Wilson
2016-09-20  8:29 ` [PATCH 19/38] drm/i915: Implement pread without struct-mutex Chris Wilson
2016-09-20  8:29 ` [PATCH 20/38] drm/i915: Implement pwrite " Chris Wilson
2016-09-20 13:47   ` kbuild test robot
2016-09-20  8:29 ` [PATCH 21/38] drm/i915: Acquire the backing storage outside of struct_mutex in set-domain Chris Wilson
2016-09-20  8:29 ` [PATCH 22/38] drm/i915: Move object release to a freelist + worker Chris Wilson
2016-09-20  8:29 ` [PATCH 23/38] drm/i915: Use lockless object free Chris Wilson
2016-09-20  8:29 ` [PATCH 24/38] drm/i915: Move GEM activity tracking into a common struct reservation_object Chris Wilson
2016-09-26  7:53   ` Joonas Lahtinen
2016-09-20  8:29 ` [PATCH 25/38] drm: Add reference counting to drm_atomic_state Chris Wilson
2016-09-21  7:24   ` Sean Paul
2016-09-20  8:30 ` [PATCH 26/38] drm/i915: Restore nonblocking awaits for modesetting Chris Wilson
2016-09-26  8:11   ` Joonas Lahtinen
2016-09-20  8:30 ` [PATCH 27/38] drm/i915: Combine seqno + tracking into a global timeline struct Chris Wilson
2016-09-20  8:30 ` [PATCH 28/38] drm/i915: Queue the idling context switch after all other timelines Chris Wilson
2016-09-26  8:49   ` Joonas Lahtinen
2016-09-20  8:30 ` [PATCH 29/38] drm/i915: Wait first for submission, before waiting for request completion Chris Wilson
2016-09-20  8:30 ` [PATCH 30/38] drm/i915: Introduce a global_seqno for each request Chris Wilson
2016-09-20  8:30 ` [PATCH 31/38] drm/i915: Record space required for request emission Chris Wilson
2016-09-20  8:30 ` [PATCH 32/38] drm/i915: Defer " Chris Wilson
2016-09-26  8:53   ` Joonas Lahtinen
2016-09-26  9:04     ` Chris Wilson
2016-09-26  9:06       ` Joonas Lahtinen
2016-09-26  9:25         ` Chris Wilson
2016-09-20  8:30 ` [PATCH 33/38] drm/i915: Move the global sync optimisation to the timeline Chris Wilson
2016-09-20  8:30 ` [PATCH 34/38] drm/i915: Create a unique name for the context Chris Wilson
2016-09-20  8:30 ` Chris Wilson [this message]
2016-09-20 18:49   ` [PATCH 35/38] drm/i915: Reserve space in the global seqno during request allocation kbuild test robot
2016-09-20 18:49   ` [PATCH] drm/i915: fix semicolon.cocci warnings kbuild test robot
2016-09-20  8:30 ` [PATCH 36/38] drm/i915: Enable multiple timelines Chris Wilson
2016-09-26  8:55   ` Joonas Lahtinen
2016-09-20  8:30 ` [PATCH 37/38] drm/i915: Enable userspace to opt-out of implicit fencing Chris Wilson
2016-09-20  8:30 ` [PATCH 38/38] drm/i915: Support explicit fencing for execbuf Chris Wilson
2016-09-20  9:24 ` ✗ Fi.CI.BAT: failure for series starting with [01/38] drm/i915: Allow disabling error capture Patchwork

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