[Intel-gfx] [PATCH v10] drm/i915: Squash repeated awaits on the same fence

Chris Wilson chris at chris-wilson.co.uk
Fri Apr 28 07:41:36 UTC 2017


Track the latest fence waited upon on each context, and only add a new
asynchronous wait if the new fence is more recent than the recorded
fence for that context. This requires us to filter out unordered
timelines, which are noted by DMA_FENCE_NO_CONTEXT. However, in the
absence of a universal identifier, we have to use our own
i915->mm.unordered_timeline token.

v2: Throw around the debug crutches
v3: Inline the likely case of the pre-allocation cache being full.
v4: Drop the pre-allocation support, we can lose the most recent fence
in case of allocation failure -- it just means we may emit more awaits
than strictly necessary but will not break.
v5: Trim allocation size for leaf nodes, they only need an array of u32
not pointers.
v6: Create mock_timeline to tidy selftest writing
v7: s/intel_timeline_sync_get/intel_timeline_sync_is_later/ (Tvrtko)
v8: Prune the stale sync points when we idle.
v9: Include a small benchmark in the kselftests
v10: Separate the idr implementation into its own compartment.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
---
 drivers/gpu/drm/i915/Makefile                      |   1 +
 drivers/gpu/drm/i915/i915_gem.c                    |   1 +
 drivers/gpu/drm/i915/i915_gem.h                    |   2 +
 drivers/gpu/drm/i915/i915_gem_request.c            |   9 +
 drivers/gpu/drm/i915/i915_gem_timeline.c           |  92 +++++-
 drivers/gpu/drm/i915/i915_gem_timeline.h           |  36 ++
 drivers/gpu/drm/i915/i915_syncmap.c                | 362 +++++++++++++++++++++
 drivers/gpu/drm/i915/i915_syncmap.h                |  39 +++
 drivers/gpu/drm/i915/selftests/i915_gem_timeline.c | 257 +++++++++++++++
 .../gpu/drm/i915/selftests/i915_mock_selftests.h   |   1 +
 drivers/gpu/drm/i915/selftests/mock_timeline.c     |  45 +++
 drivers/gpu/drm/i915/selftests/mock_timeline.h     |  33 ++
 12 files changed, 860 insertions(+), 18 deletions(-)
 create mode 100644 drivers/gpu/drm/i915/i915_syncmap.c
 create mode 100644 drivers/gpu/drm/i915/i915_syncmap.h
 create mode 100644 drivers/gpu/drm/i915/selftests/i915_gem_timeline.c
 create mode 100644 drivers/gpu/drm/i915/selftests/mock_timeline.c
 create mode 100644 drivers/gpu/drm/i915/selftests/mock_timeline.h

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 2cf04504e494..7b05fb802f4c 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -16,6 +16,7 @@ i915-y := i915_drv.o \
 	  i915_params.o \
 	  i915_pci.o \
           i915_suspend.o \
+	  i915_syncmap.o \
 	  i915_sw_fence.o \
 	  i915_sysfs.o \
 	  intel_csr.o \
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index c1fa3c103f38..f886ef492036 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3214,6 +3214,7 @@ i915_gem_idle_work_handler(struct work_struct *work)
 		intel_engine_disarm_breadcrumbs(engine);
 		i915_gem_batch_pool_fini(&engine->batch_pool);
 	}
+	i915_gem_timelines_mark_idle(dev_priv);
 
 	GEM_BUG_ON(!dev_priv->gt.awake);
 	dev_priv->gt.awake = false;
diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h
index 5a49487368ca..ee54597465b6 100644
--- a/drivers/gpu/drm/i915/i915_gem.h
+++ b/drivers/gpu/drm/i915/i915_gem.h
@@ -25,6 +25,8 @@
 #ifndef __I915_GEM_H__
 #define __I915_GEM_H__
 
+#include <linux/bug.h>
+
 #ifdef CONFIG_DRM_I915_DEBUG_GEM
 #define GEM_BUG_ON(expr) BUG_ON(expr)
 #define GEM_WARN_ON(expr) WARN_ON(expr)
diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 5fa4e52ded06..807fc1b65dd1 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -772,6 +772,11 @@ i915_gem_request_await_dma_fence(struct drm_i915_gem_request *req,
 		if (fence->context == req->fence.context)
 			continue;
 
+		/* Squash repeated waits to the same timelines */
+		if (fence->context != req->i915->mm.unordered_timeline &&
+		    intel_timeline_sync_is_later(req->timeline, fence))
+			continue;
+
 		if (dma_fence_is_i915(fence))
 			ret = i915_gem_request_await_request(req,
 							     to_request(fence));
@@ -781,6 +786,10 @@ i915_gem_request_await_dma_fence(struct drm_i915_gem_request *req,
 							    GFP_KERNEL);
 		if (ret < 0)
 			return ret;
+
+		/* Record the latest fence used against each timeline */
+		if (fence->context != req->i915->mm.unordered_timeline)
+			intel_timeline_sync_set(req->timeline, fence);
 	} while (--nchild);
 
 	return 0;
diff --git a/drivers/gpu/drm/i915/i915_gem_timeline.c b/drivers/gpu/drm/i915/i915_gem_timeline.c
index b596ca7ee058..a28a65db82e9 100644
--- a/drivers/gpu/drm/i915/i915_gem_timeline.c
+++ b/drivers/gpu/drm/i915/i915_gem_timeline.c
@@ -24,6 +24,31 @@
 
 #include "i915_drv.h"
 
+static void __intel_timeline_init(struct intel_timeline *tl,
+				  struct i915_gem_timeline *parent,
+				  u64 context,
+				  struct lock_class_key *lockclass,
+				  const char *lockname)
+{
+	tl->fence_context = context;
+	tl->common = parent;
+#ifdef CONFIG_DEBUG_SPINLOCK
+	__raw_spin_lock_init(&tl->lock.rlock, lockname, lockclass);
+#else
+	spin_lock_init(&tl->lock);
+#endif
+	init_request_active(&tl->last_request, NULL);
+	INIT_LIST_HEAD(&tl->requests);
+	i915_syncmap_init(&tl->sync);
+}
+
+static void __intel_timeline_fini(struct intel_timeline *tl)
+{
+	GEM_BUG_ON(!list_empty(&tl->requests));
+
+	i915_syncmap_free(&tl->sync);
+}
+
 static int __i915_gem_timeline_init(struct drm_i915_private *i915,
 				    struct i915_gem_timeline *timeline,
 				    const char *name,
@@ -35,6 +60,12 @@ static int __i915_gem_timeline_init(struct drm_i915_private *i915,
 
 	lockdep_assert_held(&i915->drm.struct_mutex);
 
+	/*
+	 * Ideally we want a set of engines on a single leaf as we expect
+	 * to mostly be tracking synchronisation between engines.
+	 */
+	BUILD_BUG_ON(KSYNCMAP < I915_NUM_ENGINES);
+
 	timeline->i915 = i915;
 	timeline->name = kstrdup(name ?: "[kernel]", GFP_KERNEL);
 	if (!timeline->name)
@@ -44,19 +75,10 @@ static int __i915_gem_timeline_init(struct drm_i915_private *i915,
 
 	/* Called during early_init before we know how many engines there are */
 	fences = dma_fence_context_alloc(ARRAY_SIZE(timeline->engine));
-	for (i = 0; i < ARRAY_SIZE(timeline->engine); i++) {
-		struct intel_timeline *tl = &timeline->engine[i];
-
-		tl->fence_context = fences++;
-		tl->common = timeline;
-#ifdef CONFIG_DEBUG_SPINLOCK
-		__raw_spin_lock_init(&tl->lock.rlock, lockname, lockclass);
-#else
-		spin_lock_init(&tl->lock);
-#endif
-		init_request_active(&tl->last_request, NULL);
-		INIT_LIST_HEAD(&tl->requests);
-	}
+	for (i = 0; i < ARRAY_SIZE(timeline->engine); i++)
+		__intel_timeline_init(&timeline->engine[i],
+				      timeline, fences++,
+				      lockclass, lockname);
 
 	return 0;
 }
@@ -81,18 +103,52 @@ int i915_gem_timeline_init__global(struct drm_i915_private *i915)
 					&class, "&global_timeline->lock");
 }
 
+/**
+ * i915_gem_timelines_mark_idle -- called when the driver idles
+ * @i915 - the drm_i915_private device
+ *
+ * When the driver is completely idle, we know that all of our sync points
+ * have been signaled and our tracking is then entirely redundant. Any request
+ * to wait upon an older sync point will be completed instantly as we know
+ * the fence is signaled and therefore we will not even look them up in the
+ * sync point map.
+ */
+void i915_gem_timelines_mark_idle(struct drm_i915_private *i915)
+{
+	struct i915_gem_timeline *timeline;
+	int i;
+
+	lockdep_assert_held(&i915->drm.struct_mutex);
+
+	list_for_each_entry(timeline, &i915->gt.timelines, link) {
+		for (i = 0; i < ARRAY_SIZE(timeline->engine); i++) {
+			struct intel_timeline *tl = &timeline->engine[i];
+
+			/*
+			 * All known fences are completed so we can scrap
+			 * the current sync point tracking and start afresh,
+			 * any attempt to wait upon a previous sync point
+			 * will be skipped as the fence was signaled.
+			 */
+			i915_syncmap_free(&tl->sync);
+		}
+	}
+}
+
 void i915_gem_timeline_fini(struct i915_gem_timeline *timeline)
 {
 	int i;
 
 	lockdep_assert_held(&timeline->i915->drm.struct_mutex);
 
-	for (i = 0; i < ARRAY_SIZE(timeline->engine); i++) {
-		struct intel_timeline *tl = &timeline->engine[i];
-
-		GEM_BUG_ON(!list_empty(&tl->requests));
-	}
+	for (i = 0; i < ARRAY_SIZE(timeline->engine); i++)
+		__intel_timeline_fini(&timeline->engine[i]);
 
 	list_del(&timeline->link);
 	kfree(timeline->name);
 }
+
+#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
+#include "selftests/mock_timeline.c"
+#include "selftests/i915_gem_timeline.c"
+#endif
diff --git a/drivers/gpu/drm/i915/i915_gem_timeline.h b/drivers/gpu/drm/i915/i915_gem_timeline.h
index 6c53e14cab2a..86ade2890902 100644
--- a/drivers/gpu/drm/i915/i915_gem_timeline.h
+++ b/drivers/gpu/drm/i915/i915_gem_timeline.h
@@ -27,7 +27,9 @@
 
 #include <linux/list.h>
 
+#include "i915_utils.h"
 #include "i915_gem_request.h"
+#include "i915_syncmap.h"
 
 struct i915_gem_timeline;
 
@@ -55,6 +57,15 @@ struct intel_timeline {
 	 * struct_mutex.
 	 */
 	struct i915_gem_active last_request;
+
+	/**
+	 * We track the most recent seqno that we wait on in every context so
+	 * that we only have to emit a new await and dependency on a more
+	 * recent sync point. As the contexts may executed out-of-order, we
+	 * have to track each individually and cannot not rely on an absolute
+	 * global_seqno.
+	 */
+	struct i915_syncmap *sync;
 	u32 sync_seqno[I915_NUM_ENGINES];
 
 	struct i915_gem_timeline *common;
@@ -73,6 +84,31 @@ int i915_gem_timeline_init(struct drm_i915_private *i915,
 			   struct i915_gem_timeline *tl,
 			   const char *name);
 int i915_gem_timeline_init__global(struct drm_i915_private *i915);
+void i915_gem_timelines_mark_idle(struct drm_i915_private *i915);
 void i915_gem_timeline_fini(struct i915_gem_timeline *tl);
 
+static inline int __intel_timeline_sync_set(struct intel_timeline *tl,
+					    u64 context, u32 seqno)
+{
+	return i915_syncmap_set(&tl->sync, context, seqno);
+}
+
+static inline int intel_timeline_sync_set(struct intel_timeline *tl,
+					  const struct dma_fence *fence)
+{
+	return __intel_timeline_sync_set(tl, fence->context, fence->seqno);
+}
+
+static inline bool __intel_timeline_sync_is_later(struct intel_timeline *tl,
+						  u64 context, u32 seqno)
+{
+	return i915_syncmap_is_later(&tl->sync, context, seqno);
+}
+
+static inline bool intel_timeline_sync_is_later(struct intel_timeline *tl,
+						const struct dma_fence *fence)
+{
+	return __intel_timeline_sync_is_later(tl, fence->context, fence->seqno);
+}
+
 #endif
diff --git a/drivers/gpu/drm/i915/i915_syncmap.c b/drivers/gpu/drm/i915/i915_syncmap.c
new file mode 100644
index 000000000000..70762c3772a0
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_syncmap.c
@@ -0,0 +1,362 @@
+/*
+ * Copyright © 2017 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#include <linux/slab.h>
+
+#include "i915_syncmap.h"
+
+#include "i915_gem.h" /* GEM_BUG_ON() */
+
+#define SHIFT ilog2(KSYNCMAP)
+#define MASK (KSYNCMAP - 1)
+
+/*
+ * struct i915_syncmap is a layer of a radixtree that maps a u64 fence
+ * context id to the last u32 fence seqno waited upon from that context.
+ * Unlike lib/radixtree it uses a parent pointer that allows traversal back to
+ * the root. This allows us to access the whole tree via a single pointer
+ * to the most recently used layer. We expect fence contexts to be dense
+ * and most reuse to be on the same i915_gem_context but on neighbouring
+ * engines (i.e. on adjacent contexts) and reuse the same leaf, a very
+ * effective lookup cache. If the new lookup is not on the same leaf, we
+ * expect it to be on the neighbouring branch.
+ *
+ * A leaf holds an array of u32 seqno, and has height 0. The bitmap field
+ * allows us to store whether a particular seqno is valid (i.e. allows us
+ * to distinguish unset from 0).
+ *
+ * A branch holds an array of layer pointers, and has height > 0, and always
+ * has at least 2 layers (either branches or leaves) below it.
+ */
+
+struct i915_syncmap {
+	u64 prefix;
+	unsigned int height;
+	unsigned int bitmap;
+	struct i915_syncmap *parent;
+	/*
+	 * Following this header is an array of either seqno or child pointers:
+	 * union {
+	 *	u32 seqno[KSYNCMAP];
+	 *	struct i915_syncmap *child[KSYNMAP];
+	 * };
+	 */
+};
+
+/**
+ * i915_syncmap_init -- initialise the #i915_syncmap
+ * @root - pointer to the #i915_syncmap
+ */
+void i915_syncmap_init(struct i915_syncmap **root)
+{
+	BUILD_BUG_ON(KSYNCMAP > BITS_PER_BYTE * sizeof((*root)->bitmap));
+	*root = NULL;
+}
+
+static inline u32 *__sync_seqno(struct i915_syncmap *p)
+{
+	GEM_BUG_ON(p->height);
+	return (u32 *)(p + 1);
+}
+
+static inline struct i915_syncmap **__sync_child(struct i915_syncmap *p)
+{
+	GEM_BUG_ON(!p->height);
+	return (struct i915_syncmap **)(p + 1);
+}
+
+static inline unsigned int __sync_idx(const struct i915_syncmap *p, u64 id)
+{
+	return (id >> p->height) & MASK;
+}
+
+static inline u64 __sync_prefix(const struct i915_syncmap *p, u64 id)
+{
+	return id >> p->height >> SHIFT;
+}
+
+static inline u64 __sync_leaf(const struct i915_syncmap *p, u64 id)
+{
+	GEM_BUG_ON(p->height);
+	return id >> SHIFT;
+}
+
+static inline bool seqno_later(u32 a, u32 b)
+{
+	return (s32)(a - b) >= 0;
+}
+
+/**
+ * i915_syncmap_is_later -- compare against the last know sync point
+ * @root - pointer to the #i915_syncmap
+ * @id - the context id (other timeline) we are synchronising to
+ * @seqno - the sequence number along the other timeline
+ *
+ * If we have already synchronised this @root with another (@id) then we can
+ * omit any repeated or earlier synchronisation requests. If the two timelines
+ * are already coupled, we can also omit the dependency between the two as that
+ * is already known via the timeline.
+ *
+ * Returns true if the two timelines are already synchronised wrt to @seqno,
+ * false if not and the synchronisation must be emitted.
+ */
+bool i915_syncmap_is_later(struct i915_syncmap **root, u64 id, u32 seqno)
+{
+	struct i915_syncmap *p;
+	unsigned int idx;
+
+	p = *root;
+	if (!p)
+		return false;
+
+	if (likely(__sync_leaf(p, id) == p->prefix))
+		goto found;
+
+	/* First climb the tree back to a parent branch */
+	do {
+		p = p->parent;
+		if (!p)
+			return false;
+
+		if (__sync_prefix(p, id) == p->prefix)
+			break;
+	} while (1);
+
+	/* And then descend again until we find our leaf */
+	do {
+		if (!p->height)
+			break;
+
+		p = __sync_child(p)[__sync_idx(p, id)];
+		if (!p)
+			return false;
+
+		if (__sync_prefix(p, id) != p->prefix)
+			return false;
+	} while (1);
+
+	*root = p;
+found:
+	idx = id & MASK;
+	if (!(p->bitmap & BIT(idx)))
+		return false;
+
+	return seqno_later(__sync_seqno(p)[idx], seqno);
+}
+
+static struct i915_syncmap *
+__sync_alloc_leaf(struct i915_syncmap *parent, u64 id)
+{
+	struct i915_syncmap *p;
+
+	p = kmalloc(sizeof(*p) + KSYNCMAP * sizeof(u32), GFP_KERNEL);
+	if (unlikely(!p))
+		return NULL;
+
+	p->parent = parent;
+	p->height = 0;
+	p->bitmap = 0;
+	p->prefix = __sync_leaf(p, id);
+	return p;
+}
+
+static noinline int
+__i915_syncmap_set(struct i915_syncmap **root, u64 id, u32 seqno)
+{
+	struct i915_syncmap *p = *root;
+	unsigned int idx;
+
+	if (!p) {
+		p = __sync_alloc_leaf(NULL, id);
+		if (unlikely(!p))
+			return -ENOMEM;
+
+		goto found;
+	}
+
+	/* Climb back up the tree until we find a common prefix */
+	do {
+		if (!p->parent)
+			break;
+
+		p = p->parent;
+
+		if (__sync_prefix(p, id) == p->prefix)
+			break;
+	} while (1);
+
+	/*
+	 * No shortcut, we have to descend the tree to find the right layer
+	 * containing this fence.
+	 *
+	 * Each layer in the tree holds 16 (KSYNCMAP) pointers, either fences
+	 * or lower layers. Leaf nodes (height = 0) contain the fences, all
+	 * other nodes (height > 0) are internal layers that point to a lower
+	 * node. Each internal layer has at least 2 descendents.
+	 *
+	 * Starting at the top, we check whether the current prefix matches. If
+	 * it doesn't, we have gone passed our layer and need to insert a join
+	 * into the tree, and a new leaf node as a descendent as well as the
+	 * original layer.
+	 *
+	 * The matching prefix means we are still following the right branch
+	 * of the tree. If it has height 0, we have found our leaf and just
+	 * need to replace the fence slot with ourselves. If the height is
+	 * not zero, our slot contains the next layer in the tree (unless
+	 * it is empty, in which case we can add ourselves as a new leaf).
+	 * As descend the tree the prefix grows (and height decreases).
+	 */
+	do {
+		struct i915_syncmap *next;
+
+		if (__sync_prefix(p, id) != p->prefix) {
+			unsigned int above;
+
+			/* insert a join above the current layer */
+			next = kzalloc(sizeof(*next) + KSYNCMAP * sizeof(next),
+				       GFP_KERNEL);
+			if (unlikely(!next))
+				return -ENOMEM;
+
+			above = fls64(__sync_prefix(p, id) ^ p->prefix);
+			above = round_up(above, SHIFT);
+			next->height = above + p->height;
+			next->prefix = __sync_prefix(next, id);
+
+			if (p->parent)
+				__sync_child(p->parent)[__sync_idx(p->parent, id)] = next;
+			next->parent = p->parent;
+
+			idx = p->prefix >> (above - SHIFT) & MASK;
+			__sync_child(next)[idx] = p;
+			next->bitmap |= BIT(idx);
+			p->parent = next;
+
+			/* ascend to the join */
+			p = next;
+		} else {
+			if (!p->height)
+				break;
+		}
+
+		/* descend into the next layer */
+		GEM_BUG_ON(!p->height);
+		idx = __sync_idx(p, id);
+		next = __sync_child(p)[idx];
+		if (unlikely(!next)) {
+			next = __sync_alloc_leaf(p, id);
+			if (unlikely(!next))
+				return -ENOMEM;
+
+			__sync_child(p)[idx] = next;
+			p->bitmap |= BIT(idx);
+
+			p = next;
+			break;
+		}
+
+		p = next;
+	} while (1);
+
+found:
+	GEM_BUG_ON(p->prefix != __sync_leaf(p, id));
+	idx = id & MASK;
+	__sync_seqno(p)[idx] = seqno;
+	p->bitmap |= BIT(idx);
+	*root = p;
+	return 0;
+}
+
+/**
+ * i915_syncmap_set -- mark the most recent syncpoint between contexts
+ * @root - pointer to the #i915_syncmap
+ * @id - the context id (other timeline) we have synchronised to
+ * @seqno - the sequence number along the other timeline
+ *
+ * When we synchronise this @root with another (@id), we also know that we have
+ * synchronized with all previous seqno along that timeline. If we then have
+ * a request to synchronise with the same seqno or older, we can omit it,
+ * see i915_syncmap_is_later()
+ *
+ * Returns 0 on success, or a negative error code.
+ */
+int i915_syncmap_set(struct i915_syncmap **root, u64 id, u32 seqno)
+{
+	struct i915_syncmap *p = *root;
+
+	/*
+	 * We expect to be called in sequence following a is_later(id), which
+	 * should have preloaded the root for us.
+	 */
+	if (likely(p && __sync_leaf(p, id) == p->prefix)) {
+		unsigned int idx = id & MASK;
+
+		__sync_seqno(p)[idx] = seqno;
+		p->bitmap |= BIT(idx);
+		return 0;
+	}
+
+	return __i915_syncmap_set(root, id, seqno);
+}
+
+static void __sync_free(struct i915_syncmap *p)
+{
+	if (p->height) {
+		unsigned int i;
+
+		while ((i = ffs(p->bitmap))) {
+			p->bitmap &= ~0u << i;
+			__sync_free(__sync_child(p)[i - 1]);
+		}
+	}
+
+	kfree(p);
+}
+
+/**
+ * i915_syncmap_free -- free all memory associated with the syncmap
+ * @root - pointer to the #i915_syncmap
+ *
+ * Either when the timeline is to be freed and we no longer need the sync
+ * point tracking, or when the fences are all known to be signaled and the
+ * sync point tracking is redundant, we can free the #i915_syncmap to recover
+ * its allocations.
+ *
+ * Will reinitialise the @root pointer so that the #i915_syncmap is ready for
+ * reuse.
+ */
+void i915_syncmap_free(struct i915_syncmap **root)
+{
+	struct i915_syncmap *p;
+
+	p = *root;
+	if (!p)
+		return;
+
+	while (p->parent)
+		p = p->parent;
+
+	__sync_free(p);
+	*root = NULL;
+}
diff --git a/drivers/gpu/drm/i915/i915_syncmap.h b/drivers/gpu/drm/i915/i915_syncmap.h
new file mode 100644
index 000000000000..7ca827d812ae
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_syncmap.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright © 2017 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#ifndef __I915_SYNCMAP_H__
+#define __I915_SYNCMAP_H__
+
+#include <linux/types.h>
+
+struct i915_syncmap;
+
+void i915_syncmap_init(struct i915_syncmap **root);
+bool i915_syncmap_is_later(struct i915_syncmap **root, u64 id, u32 seqno);
+int i915_syncmap_set(struct i915_syncmap **root, u64 id, u32 seqno);
+void i915_syncmap_free(struct i915_syncmap **root);
+
+#define KSYNCMAP 16
+
+#endif /* __I915_SYNCMAP_H__ */
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_timeline.c b/drivers/gpu/drm/i915/selftests/i915_gem_timeline.c
new file mode 100644
index 000000000000..2058e754c86d
--- /dev/null
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_timeline.c
@@ -0,0 +1,257 @@
+/*
+ * Copyright © 2017 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#include <linux/random.h>
+
+#include "../i915_selftest.h"
+#include "mock_gem_device.h"
+#include "mock_timeline.h"
+
+static int igt_sync(void *arg)
+{
+	const struct {
+		const char *name;
+		u32 seqno;
+		bool expected;
+		bool set;
+	} pass[] = {
+		{ "unset", 0, false, false },
+		{ "new", 0, false, true },
+		{ "0a", 0, true, true },
+		{ "1a", 1, false, true },
+		{ "1b", 1, true, true },
+		{ "0b", 0, true, false },
+		{ "2a", 2, false, true },
+		{ "4", 4, false, true },
+		{ "INT_MAX", INT_MAX, false, true },
+		{ "INT_MAX-1", INT_MAX-1, true, false },
+		{ "INT_MAX+1", (u32)INT_MAX+1, false, true },
+		{ "INT_MAX", INT_MAX, true, false },
+		{ "UINT_MAX", UINT_MAX, false, true },
+		{ "wrap", 0, false, true },
+		{ "unwrap", UINT_MAX, true, false },
+		{},
+	}, *p;
+	struct intel_timeline *tl;
+	int order, offset;
+	int ret;
+
+	tl = mock_timeline(0);
+	if (!tl)
+		return -ENOMEM;
+
+	for (p = pass; p->name; p++) {
+		for (order = 1; order < 64; order++) {
+			for (offset = -1; offset <= (order > 1); offset++) {
+				u64 ctx = BIT_ULL(order) + offset;
+
+				if (__intel_timeline_sync_is_later
+				    (tl, ctx, p->seqno) != p->expected) {
+					pr_err("1: %s(ctx=%llu, seqno=%u) expected passed %s but failed\n",
+					       p->name, ctx, p->seqno, yesno(p->expected));
+					ret = -EINVAL;
+					goto out;
+				}
+
+				if (p->set) {
+					ret = __intel_timeline_sync_set(tl, ctx, p->seqno);
+					if (ret)
+						goto out;
+				}
+			}
+		}
+	}
+	mock_timeline_destroy(tl);
+
+	tl = mock_timeline(0);
+	if (!tl)
+		return -ENOMEM;
+
+	for (order = 1; order < 64; order++) {
+		for (offset = -1; offset <= (order > 1); offset++) {
+			u64 ctx = BIT_ULL(order) + offset;
+
+			for (p = pass; p->name; p++) {
+				if (__intel_timeline_sync_is_later
+				    (tl, ctx, p->seqno) != p->expected) {
+					pr_err("2: %s(ctx=%llu, seqno=%u) expected passed %s but failed\n",
+					       p->name, ctx, p->seqno, yesno(p->expected));
+					ret = -EINVAL;
+					goto out;
+				}
+
+				if (p->set) {
+					ret = __intel_timeline_sync_set(tl, ctx, p->seqno);
+					if (ret)
+						goto out;
+				}
+			}
+		}
+	}
+
+out:
+	mock_timeline_destroy(tl);
+	return ret;
+}
+
+static u64 prandom_u64_state(struct rnd_state *rnd)
+{
+	u64 x;
+
+	x = prandom_u32_state(rnd);
+	x <<= 32;
+	x |= prandom_u32_state(rnd);
+
+	return x;
+}
+
+static unsigned int random_engine(struct rnd_state *rnd)
+{
+	return ((u64)prandom_u32_state(rnd) * I915_NUM_ENGINES) >> 32;
+}
+
+static int bench_sync(void *arg)
+{
+	struct rnd_state prng;
+	struct intel_timeline *tl;
+	unsigned long end_time, count;
+	ktime_t kt;
+
+	tl = mock_timeline(0);
+	if (!tl)
+		return -ENOMEM;
+
+	prandom_seed_state(&prng, i915_selftest.random_seed);
+	count = 0;
+	kt = ktime_get();
+	end_time = jiffies + HZ/10;
+	do {
+		u64 id = prandom_u64_state(&prng);
+
+		__intel_timeline_sync_set(tl, id, 0);
+		count++;
+	} while (!time_after(jiffies, end_time));
+	kt = ktime_sub(ktime_get(), kt);
+	pr_info("%s: %lu random insertions, %lluns/insert\n",
+		__func__, count, (long long)div64_ul(ktime_to_ns(kt), count));
+
+	prandom_seed_state(&prng, i915_selftest.random_seed);
+	end_time = count;
+	kt = ktime_get();
+	while (end_time--) {
+		u64 id = prandom_u64_state(&prng);
+
+		if (!__intel_timeline_sync_is_later(tl, id, 0)) {
+			mock_timeline_destroy(tl);
+			pr_err("Lookup of %llu failed\n", id);
+			return -EINVAL;
+		}
+	}
+	kt = ktime_sub(ktime_get(), kt);
+	pr_info("%s: %lu random lookups, %lluns/lookup\n",
+		__func__, count, (long long)div64_ul(ktime_to_ns(kt), count));
+
+	mock_timeline_destroy(tl);
+
+	tl = mock_timeline(0);
+	if (!tl)
+		return -ENOMEM;
+
+	count = 0;
+	kt = ktime_get();
+	end_time = jiffies + HZ/10;
+	do {
+		__intel_timeline_sync_set(tl, count++, 0);
+	} while (!time_after(jiffies, end_time));
+	kt = ktime_sub(ktime_get(), kt);
+	pr_info("%s: %lu in-order insertions, %lluns/insert\n",
+		__func__, count, (long long)div64_ul(ktime_to_ns(kt), count));
+
+	end_time = count;
+	kt = ktime_get();
+	while (end_time--) {
+		if (!__intel_timeline_sync_is_later(tl, end_time, 0)) {
+			pr_err("Lookup of %lu failed\n", end_time);
+			mock_timeline_destroy(tl);
+			return -EINVAL;
+		}
+	}
+	kt = ktime_sub(ktime_get(), kt);
+	pr_info("%s: %lu in-order lookups, %lluns/lookup\n",
+		__func__, count, (long long)div64_ul(ktime_to_ns(kt), count));
+
+	mock_timeline_destroy(tl);
+
+	tl = mock_timeline(0);
+	if (!tl)
+		return -ENOMEM;
+
+	prandom_seed_state(&prng, i915_selftest.random_seed);
+	count = 0;
+	kt = ktime_get();
+	end_time = jiffies + HZ/10;
+	do {
+		u32 id = random_engine(&prng);
+		u32 seqno = prandom_u32_state(&prng);
+
+		if (!__intel_timeline_sync_is_later(tl, id, seqno))
+			__intel_timeline_sync_set(tl, id, seqno);
+
+		count++;
+	} while (!time_after(jiffies, end_time));
+	kt = ktime_sub(ktime_get(), kt);
+	pr_info("%s: %lu repeated insert/lookups, %lluns/op\n",
+		__func__, count, (long long)div64_ul(ktime_to_ns(kt), count));
+	mock_timeline_destroy(tl);
+
+	tl = mock_timeline(0);
+	if (!tl)
+		return -ENOMEM;
+
+	count = 0;
+	kt = ktime_get();
+	end_time = jiffies + HZ/10;
+	do {
+		if (!__intel_timeline_sync_is_later(tl, count & 7, count >> 4))
+			__intel_timeline_sync_set(tl, count & 7, count >> 4);
+
+		count++;
+	} while (!time_after(jiffies, end_time));
+	kt = ktime_sub(ktime_get(), kt);
+	pr_info("%s: %lu cyclic insert/lookups, %lluns/op\n",
+		__func__, count, (long long)div64_ul(ktime_to_ns(kt), count));
+	mock_timeline_destroy(tl);
+
+	return 0;
+}
+
+int i915_gem_timeline_mock_selftests(void)
+{
+	static const struct i915_subtest tests[] = {
+		SUBTEST(igt_sync),
+		SUBTEST(bench_sync),
+	};
+
+	return i915_subtests(tests, NULL);
+}
diff --git a/drivers/gpu/drm/i915/selftests/i915_mock_selftests.h b/drivers/gpu/drm/i915/selftests/i915_mock_selftests.h
index be9a9ebf5692..8d0f50c25df8 100644
--- a/drivers/gpu/drm/i915/selftests/i915_mock_selftests.h
+++ b/drivers/gpu/drm/i915/selftests/i915_mock_selftests.h
@@ -12,6 +12,7 @@ selftest(sanitycheck, i915_mock_sanitycheck) /* keep first (igt selfcheck) */
 selftest(scatterlist, scatterlist_mock_selftests)
 selftest(uncore, intel_uncore_mock_selftests)
 selftest(breadcrumbs, intel_breadcrumbs_mock_selftests)
+selftest(timelines, i915_gem_timeline_mock_selftests)
 selftest(requests, i915_gem_request_mock_selftests)
 selftest(objects, i915_gem_object_mock_selftests)
 selftest(dmabuf, i915_gem_dmabuf_mock_selftests)
diff --git a/drivers/gpu/drm/i915/selftests/mock_timeline.c b/drivers/gpu/drm/i915/selftests/mock_timeline.c
new file mode 100644
index 000000000000..47b1f47c5812
--- /dev/null
+++ b/drivers/gpu/drm/i915/selftests/mock_timeline.c
@@ -0,0 +1,45 @@
+/*
+ * Copyright © 2017 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#include "mock_timeline.h"
+
+struct intel_timeline *mock_timeline(u64 context)
+{
+	static struct lock_class_key class;
+	struct intel_timeline *tl;
+
+	tl = kzalloc(sizeof(*tl), GFP_KERNEL);
+	if (!tl)
+		return NULL;
+
+	__intel_timeline_init(tl, NULL, context, &class, "mock");
+
+	return tl;
+}
+
+void mock_timeline_destroy(struct intel_timeline *tl)
+{
+	__intel_timeline_fini(tl);
+	kfree(tl);
+}
diff --git a/drivers/gpu/drm/i915/selftests/mock_timeline.h b/drivers/gpu/drm/i915/selftests/mock_timeline.h
new file mode 100644
index 000000000000..c27ff4639b8b
--- /dev/null
+++ b/drivers/gpu/drm/i915/selftests/mock_timeline.h
@@ -0,0 +1,33 @@
+/*
+ * Copyright © 2017 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#ifndef __MOCK_TIMELINE__
+#define __MOCK_TIMELINE__
+
+#include "../i915_gem_timeline.h"
+
+struct intel_timeline *mock_timeline(u64 context);
+void mock_timeline_destroy(struct intel_timeline *tl);
+
+#endif /* !__MOCK_TIMELINE__ */
-- 
2.11.0



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