Skip to contentSkip to conversation

dma-fence: Deadline awareness

PATCH Superseded Rob Clark 3 participants 20 messages Feb 20, 2023 – Feb 22, 2023

Subsystems (10)

v5 of 10 Superseded Latest is v10 →

lore
Share & tools
lore

Rob Clark

author
#0 lore raw

v5 cover dma-fence: Deadline awareness

From: Rob Clark <[email protected]>

This series adds a deadline hint to fences, so realtime deadlines such as vblank can be communicated to the fence signaller for power/ frequency management decisions.

This is partially inspired by a trick i915 does, but implemented via dma-fence for a couple of reasons:

1) To continue to be able to use the atomic helpers
2) To support cases where display and gpu are different drivers

This iteration adds a dma-fence ioctl to set a deadline (both to support igt-tests, and compositors which delay decisions about which client buffer to display), and a sw_sync ioctl to read back the deadline. IGT tests utilizing these can be found at:

https://gitlab.freedesktop.org/robclark/igt-gpu-tools/-/commits/fence-deadline

v1: https://patchwork.freedesktop.org/series/93035/
v2: Move filtering out of later deadlines to fence implementation
to avoid increasing the size of dma_fence
v3: Add support in fence-array and fence-chain; Add some uabi to
support igt tests and userspace compositors.
v4: Rebase, address various comments, and add syncobj deadline
support, and sync_file EPOLLPRI based on experience with perf/ freq issues with clvk compute workloads on i915 (anv)
v5: Clarify that this is a hint as opposed to a more hard deadline
guarantee, switch to using u64 ns values in UABI (still absolute CLOCK_MONOTONIC values), drop syncobj related cap and driver feature flag in favor of allowing count_handles==0 for probing kernel support.

Rob Clark (14):
dma-buf/dma-fence: Add deadline awareness dma-buf/fence-array: Add fence deadline support dma-buf/fence-chain: Add fence deadline support dma-buf/dma-resv: Add a way to set fence deadline dma-buf/sync_file: Add SET_DEADLINE ioctl dma-buf/sync_file: Support (E)POLLPRI dma-buf/sw_sync: Add fence deadline support drm/scheduler: Add fence deadline support drm/syncobj: Add deadline support for syncobj waits drm/vblank: Add helper to get next vblank time drm/atomic-helper: Set fence deadline for vblank drm/msm: Add deadline based boost support drm/msm: Add wait-boost support
drm/i915: Add deadline based boost support

 drivers/dma-buf/dma-fence-array.c       | 11 ++++
 drivers/dma-buf/dma-fence-chain.c       | 13 +++++
 drivers/dma-buf/dma-fence.c             | 21 +++++++
 drivers/dma-buf/dma-resv.c              | 22 ++++++++
 drivers/dma-buf/sw_sync.c               | 58 +++++++++++++++++++
 drivers/dma-buf/sync_debug.h            |  2 +
 drivers/dma-buf/sync_file.c             | 27 +++++++++
 drivers/gpu/drm/drm_atomic_helper.c     | 36 ++++++++++++
 drivers/gpu/drm/drm_syncobj.c           | 59 +++++++++++++++-----
 drivers/gpu/drm/drm_vblank.c            | 32 +++++++++++
 drivers/gpu/drm/i915/i915_request.c     | 20 +++++++
 drivers/gpu/drm/msm/msm_drv.c           | 12 ++--
 drivers/gpu/drm/msm/msm_fence.c         | 74 +++++++++++++++++++++++++
 drivers/gpu/drm/msm/msm_fence.h         | 20 +++++++
 drivers/gpu/drm/msm/msm_gem.c           |  5 ++
 drivers/gpu/drm/scheduler/sched_fence.c | 46 +++++++++++++++
 drivers/gpu/drm/scheduler/sched_main.c  |  2 +-
 include/drm/drm_vblank.h                |  1 +
 include/drm/gpu_scheduler.h             |  8 +++
 include/linux/dma-fence.h               | 20 +++++++
 include/linux/dma-resv.h                |  2 +
 include/uapi/drm/drm.h                  |  5 ++
 include/uapi/drm/msm_drm.h              | 14 ++++-
 include/uapi/linux/sync_file.h          | 23 ++++++++
 24 files changed, 513 insertions(+), 20 deletions(-)
Signature · 1 line
2.39.1
author
#1 lore raw

PATCH v5 1/14 dma-buf/dma-fence: Add deadline awareness

From: Rob Clark <[email protected]>

Add a way to hint to the fence signaler of an upcoming deadline, such as vblank, which the fence waiter would prefer not to miss. This is to aid the fence signaler in making power management decisions, like boosting frequency as the deadline approaches and awareness of missing deadlines so that can be factored in to the frequency scaling.

v2: Drop dma_fence::deadline and related logic to filter duplicate
deadlines, to avoid increasing dma_fence size. The fence-context implementation will need similar logic to track deadlines of all the fences on the same timeline. [ckoenig]
v3: Clarify locking wrt. set_deadline callback
v4: Clarify in docs comment that this is a hint

---
 drivers/dma-buf/dma-fence.c | 21 +++++++++++++++++++++
 include/linux/dma-fence.h   | 20 ++++++++++++++++++++
 2 files changed, 41 insertions(+)
drivers/dma-buf/dma-fence.c +21 -0
index 0de0482cd36e..e3331761384c 100644
@@ -912,6 +912,27 @@ dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
 }
 EXPORT_SYMBOL(dma_fence_wait_any_timeout);
 
+
+/**
+ * dma_fence_set_deadline - set desired fence-wait deadline
+ * @fence:    the fence that is to be waited on
+ * @deadline: the time by which the waiter hopes for the fence to be
+ *            signaled
+ *
+ * Give the fence signaler a hint about an upcoming deadline, such as
+ * vblank, by which point the waiter would prefer the fence to be
+ * signaled by.  This is intended to give feedback to the fence signaler
+ * to aid in power management decisions, such as boosting GPU frequency
+ * if a periodic vblank deadline is approaching but the fence is not
+ * yet signaled..
+ */
+void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline)
+{
+	if (fence->ops->set_deadline && !dma_fence_is_signaled(fence))
+		fence->ops->set_deadline(fence, deadline);
+}
+EXPORT_SYMBOL(dma_fence_set_deadline);
+
 /**
  * dma_fence_describe - Dump fence describtion into seq_file
  * @fence: the 6fence to describe
include/linux/dma-fence.h +20 -0
index 775cdc0b4f24..d77f6591c453 100644
@@ -99,6 +99,7 @@ enum dma_fence_flag_bits {
 	DMA_FENCE_FLAG_SIGNALED_BIT,
 	DMA_FENCE_FLAG_TIMESTAMP_BIT,
 	DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
+	DMA_FENCE_FLAG_HAS_DEADLINE_BIT,
 	DMA_FENCE_FLAG_USER_BITS, /* must always be last member */
 };
 
@@ -257,6 +258,23 @@ struct dma_fence_ops {
 	 */
 	void (*timeline_value_str)(struct dma_fence *fence,
 				   char *str, int size);
+
+	/**
+	 * @set_deadline:
+	 *
+	 * Callback to allow a fence waiter to inform the fence signaler of
+	 * an upcoming deadline, such as vblank, by which point the waiter
+	 * would prefer the fence to be signaled by.  This is intended to
+	 * give feedback to the fence signaler to aid in power management
+	 * decisions, such as boosting GPU frequency.
+	 *
+	 * This is called without &dma_fence.lock held, it can be called
+	 * multiple times and from any context.  Locking is up to the callee
+	 * if it has some state to manage.
+	 *
+	 * This callback is optional.
+	 */
+	void (*set_deadline)(struct dma_fence *fence, ktime_t deadline);
 };
 
 void dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
@@ -583,6 +601,8 @@ static inline signed long dma_fence_wait(struct dma_fence *fence, bool intr)
 	return ret < 0 ? ret : 0;
 }
 
+void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline);
+
 struct dma_fence *dma_fence_get_stub(void);
 struct dma_fence *dma_fence_allocate_private_stub(void);
 u64 dma_fence_context_alloc(unsigned num);
Signature · 1 line
2.39.1
author
#2 lore raw

PATCH v5 2/14 dma-buf/fence-array: Add fence deadline support

In reply to Rob Clark

From: Rob Clark <[email protected]>

Propagate the deadline to all the fences in the array.

---
 drivers/dma-buf/dma-fence-array.c | 11 +++++++++++
 1 file changed, 11 insertions(+)
drivers/dma-buf/dma-fence-array.c +11 -0
index 5c8a7084577b..9b3ce8948351 100644
@@ -123,12 +123,23 @@ static void dma_fence_array_release(struct dma_fence *fence)
 	dma_fence_free(fence);
 }
 
+static void dma_fence_array_set_deadline(struct dma_fence *fence,
+					 ktime_t deadline)
+{
+	struct dma_fence_array *array = to_dma_fence_array(fence);
+	unsigned i;
+
+	for (i = 0; i < array->num_fences; ++i)
+		dma_fence_set_deadline(array->fences[i], deadline);
+}
+
 const struct dma_fence_ops dma_fence_array_ops = {
 	.get_driver_name = dma_fence_array_get_driver_name,
 	.get_timeline_name = dma_fence_array_get_timeline_name,
 	.enable_signaling = dma_fence_array_enable_signaling,
 	.signaled = dma_fence_array_signaled,
 	.release = dma_fence_array_release,
+	.set_deadline = dma_fence_array_set_deadline,
 };
 EXPORT_SYMBOL(dma_fence_array_ops);
 
Signature · 1 line
2.39.1
author
#3 lore raw

PATCH v5 3/14 dma-buf/fence-chain: Add fence deadline support

In reply to Rob Clark

From: Rob Clark <[email protected]>

Propagate the deadline to all the fences in the chain.

---
 drivers/dma-buf/dma-fence-chain.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)
drivers/dma-buf/dma-fence-chain.c +13 -0
index a0d920576ba6..4684874af612 100644
@@ -206,6 +206,18 @@ static void dma_fence_chain_release(struct dma_fence *fence)
 	dma_fence_free(fence);
 }
 
+
+static void dma_fence_chain_set_deadline(struct dma_fence *fence,
+					 ktime_t deadline)
+{
+	dma_fence_chain_for_each(fence, fence) {
+		struct dma_fence_chain *chain = to_dma_fence_chain(fence);
+		struct dma_fence *f = chain ? chain->fence : fence;
+
+		dma_fence_set_deadline(f, deadline);
+	}
+}
+
 const struct dma_fence_ops dma_fence_chain_ops = {
 	.use_64bit_seqno = true,
 	.get_driver_name = dma_fence_chain_get_driver_name,
@@ -213,6 +225,7 @@ const struct dma_fence_ops dma_fence_chain_ops = {
 	.enable_signaling = dma_fence_chain_enable_signaling,
 	.signaled = dma_fence_chain_signaled,
 	.release = dma_fence_chain_release,
+	.set_deadline = dma_fence_chain_set_deadline,
 };
 EXPORT_SYMBOL(dma_fence_chain_ops);
 
Signature · 1 line
2.39.1
author
#4 lore raw

PATCH v5 4/14 dma-buf/dma-resv: Add a way to set fence deadline

In reply to Rob Clark

From: Rob Clark <[email protected]>

Add a way to set a deadline on remaining resv fences according to the requested usage.

---
 drivers/dma-buf/dma-resv.c | 22 ++++++++++++++++++++++
 include/linux/dma-resv.h   |  2 ++
 2 files changed, 24 insertions(+)
drivers/dma-buf/dma-resv.c +22 -0
index 1c76aed8e262..2a594b754af1 100644
@@ -684,6 +684,28 @@ long dma_resv_wait_timeout(struct dma_resv *obj, enum dma_resv_usage usage,
 }
 EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
 
+/**
+ * dma_resv_set_deadline - Set a deadline on reservation's objects fences
+ * @obj: the reservation object
+ * @usage: controls which fences to include, see enum dma_resv_usage.
+ * @deadline: the requested deadline (MONOTONIC)
+ *
+ * May be called without holding the dma_resv lock.  Sets @deadline on
+ * all fences filtered by @usage.
+ */
+void dma_resv_set_deadline(struct dma_resv *obj, enum dma_resv_usage usage,
+			   ktime_t deadline)
+{
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
+
+	dma_resv_iter_begin(&cursor, obj, usage);
+	dma_resv_for_each_fence_unlocked(&cursor, fence) {
+		dma_fence_set_deadline(fence, deadline);
+	}
+	dma_resv_iter_end(&cursor);
+}
+EXPORT_SYMBOL_GPL(dma_resv_set_deadline);
 
 /**
  * dma_resv_test_signaled - Test if a reservation object's fences have been
include/linux/dma-resv.h +2 -0
index 0637659a702c..8d0e34dad446 100644
@@ -479,6 +479,8 @@ int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage,
 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
 long dma_resv_wait_timeout(struct dma_resv *obj, enum dma_resv_usage usage,
 			   bool intr, unsigned long timeout);
+void dma_resv_set_deadline(struct dma_resv *obj, enum dma_resv_usage usage,
+			   ktime_t deadline);
 bool dma_resv_test_signaled(struct dma_resv *obj, enum dma_resv_usage usage);
 void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq);
 
Signature · 1 line
2.39.1
author
#5 lore raw

PATCH v5 5/14 dma-buf/sync_file: Add SET_DEADLINE ioctl

In reply to Rob Clark

From: Rob Clark <[email protected]>

The initial purpose is for igt tests, but this would also be useful for compositors that wait until close to vblank deadline to make decisions about which frame to show.

The igt tests can be found at:

https://gitlab.freedesktop.org/robclark/igt-gpu-tools/-/commits/fence-deadline

v2: Clarify the timebase, add link to igt tests
v3: Use u64 value in ns to express deadline.

---
 drivers/dma-buf/sync_file.c    | 19 +++++++++++++++++++
 include/uapi/linux/sync_file.h | 23 +++++++++++++++++++++++
 2 files changed, 42 insertions(+)
drivers/dma-buf/sync_file.c +19 -0
index af57799c86ce..418021cfb87c 100644
@@ -350,6 +350,22 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
 	return ret;
 }
 
+static int sync_file_ioctl_set_deadline(struct sync_file *sync_file,
+					unsigned long arg)
+{
+	struct sync_set_deadline ts;
+
+	if (copy_from_user(&ts, (void __user *)arg, sizeof(ts)))
+		return -EFAULT;
+
+	if (ts.pad)
+		return -EINVAL;
+
+	dma_fence_set_deadline(sync_file->fence, ns_to_ktime(ts.deadline_ns));
+
+	return 0;
+}
+
 static long sync_file_ioctl(struct file *file, unsigned int cmd,
 			    unsigned long arg)
 {
@@ -362,6 +378,9 @@ static long sync_file_ioctl(struct file *file, unsigned int cmd,
 	case SYNC_IOC_FILE_INFO:
 		return sync_file_ioctl_fence_info(sync_file, arg);
 
+	case SYNC_IOC_SET_DEADLINE:
+		return sync_file_ioctl_set_deadline(sync_file, arg);
+
 	default:
 		return -ENOTTY;
 	}
include/uapi/linux/sync_file.h +23 -0
index ee2dcfb3d660..6d2ad4addf1b 100644
@@ -67,6 +67,21 @@ struct sync_file_info {
 	__u64	sync_fence_info;
 };
 
+/**
+ * struct sync_set_deadline - set a deadline hint on a fence
+ * @deadline_ns: absolute time of the deadline
+ * @pad:	must be zero
+ *
+ * The timebase for the deadline is CLOCK_MONOTONIC (same as vblank)
+ */
+struct sync_set_deadline {
+	__u64	deadline_ns;
+	/* Not strictly needed for alignment but gives some possibility
+	 * for future extension:
+	 */
+	__u64	pad;
+};
+
 #define SYNC_IOC_MAGIC		'>'
 
 /**
@@ -95,4 +110,12 @@ struct sync_file_info {
  */
 #define SYNC_IOC_FILE_INFO	_IOWR(SYNC_IOC_MAGIC, 4, struct sync_file_info)
 
+
+/**
+ * DOC: SYNC_IOC_SET_DEADLINE - set a deadline on a fence
+ *
+ * Allows userspace to set a deadline on a fence, see dma_fence_set_deadline()
+ */
+#define SYNC_IOC_SET_DEADLINE	_IOW(SYNC_IOC_MAGIC, 5, struct sync_set_deadline)
+
 #endif /* _UAPI_LINUX_SYNC_H */
Signature · 1 line
2.39.1
author
#6 lore raw

PATCH v5 6/14 dma-buf/sync_file: Support (E)POLLPRI

In reply to Rob Clark

From: Rob Clark <[email protected]>

Allow userspace to use the EPOLLPRI/POLLPRI flag to indicate an urgent wait (as opposed to a "housekeeping" wait to know when to cleanup after some work has completed). Usermode components of GPU driver stacks often poll() on fence fd's to know when it is safe to do things like free or reuse a buffer, but they can also poll() on a fence fd when waiting to read back results from the GPU. The EPOLLPRI/POLLPRI flag lets the kernel differentiate these two cases.

---
 drivers/dma-buf/sync_file.c | 8 ++++++++
 1 file changed, 8 insertions(+)
drivers/dma-buf/sync_file.c +8 -0
index 418021cfb87c..cbe96295373b 100644
@@ -192,6 +192,14 @@ static __poll_t sync_file_poll(struct file *file, poll_table *wait)
 {
 	struct sync_file *sync_file = file->private_data;
 
+	/*
+	 * The POLLPRI/EPOLLPRI flag can be used to signal that
+	 * userspace wants the fence to signal ASAP, express this
+	 * as an immediate deadline.
+	 */
+	if (poll_requested_events(wait) & EPOLLPRI)
+		dma_fence_set_deadline(sync_file->fence, ktime_get());
+
 	poll_wait(file, &sync_file->wq, wait);
 
 	if (list_empty(&sync_file->cb.node) &&
Signature · 1 line
2.39.1
author
#7 lore raw

PATCH v5 7/14 dma-buf/sw_sync: Add fence deadline support

In reply to Rob Clark

From: Rob Clark <[email protected]>

This consists of simply storing the most recent deadline, and adding an ioctl to retrieve the deadline. This can be used in conjunction with the SET_DEADLINE ioctl on a fence fd for testing. Ie. create various sw_sync fences, merge them into a fence-array, set deadline on the fence-array and confirm that it is propagated properly to each fence.

v2: Switch UABI to express deadline as u64

---
 drivers/dma-buf/sw_sync.c    | 58 ++++++++++++++++++++++++++++++++++++
 drivers/dma-buf/sync_debug.h |  2 ++
 2 files changed, 60 insertions(+)
drivers/dma-buf/sw_sync.c +58 -0
index 348b3a9170fa..3e2315ee955b 100644
@@ -52,12 +52,28 @@ struct sw_sync_create_fence_data {
 	__s32	fence; /* fd of new fence */
 };
 
+/**
+ * struct sw_sync_get_deadline - get the deadline hint of a sw_sync fence
+ * @deadline_ns: absolute time of the deadline
+ * @pad:	must be zero
+ * @fence_fd:	the sw_sync fence fd (in)
+ *
+ * The timebase for the deadline is CLOCK_MONOTONIC (same as vblank)
+ */
+struct sw_sync_get_deadline {
+	__u64	deadline_ns;
+	__u32	pad;
+	__s32	fence_fd;
+};
+
 #define SW_SYNC_IOC_MAGIC	'W'
 
 #define SW_SYNC_IOC_CREATE_FENCE	_IOWR(SW_SYNC_IOC_MAGIC, 0,\
 		struct sw_sync_create_fence_data)
 
 #define SW_SYNC_IOC_INC			_IOW(SW_SYNC_IOC_MAGIC, 1, __u32)
+#define SW_SYNC_GET_DEADLINE		_IOWR(SW_SYNC_IOC_MAGIC, 2, \
+		struct sw_sync_get_deadline)
 
 static const struct dma_fence_ops timeline_fence_ops;
 
@@ -171,6 +187,13 @@ static void timeline_fence_timeline_value_str(struct dma_fence *fence,
 	snprintf(str, size, "%d", parent->value);
 }
 
+static void timeline_fence_set_deadline(struct dma_fence *fence, ktime_t deadline)
+{
+	struct sync_pt *pt = dma_fence_to_sync_pt(fence);
+
+	pt->deadline = deadline;
+}
+
 static const struct dma_fence_ops timeline_fence_ops = {
 	.get_driver_name = timeline_fence_get_driver_name,
 	.get_timeline_name = timeline_fence_get_timeline_name,
@@ -179,6 +202,7 @@ static const struct dma_fence_ops timeline_fence_ops = {
 	.release = timeline_fence_release,
 	.fence_value_str = timeline_fence_value_str,
 	.timeline_value_str = timeline_fence_timeline_value_str,
+	.set_deadline = timeline_fence_set_deadline,
 };
 
 /**
@@ -387,6 +411,37 @@ static long sw_sync_ioctl_inc(struct sync_timeline *obj, unsigned long arg)
 	return 0;
 }
 
+static int sw_sync_ioctl_get_deadline(struct sync_timeline *obj, unsigned long arg)
+{
+	struct sw_sync_get_deadline data;
+	struct dma_fence *fence;
+	struct sync_pt *pt;
+
+	if (copy_from_user(&data, (void __user *)arg, sizeof(data)))
+		return -EFAULT;
+
+	if (data.deadline_ns || data.pad)
+		return -EINVAL;
+
+	fence = sync_file_get_fence(data.fence_fd);
+	if (!fence)
+		return -EINVAL;
+
+	pt = dma_fence_to_sync_pt(fence);
+	if (!pt)
+		return -EINVAL;
+
+
+	data.deadline_ns = ktime_to_ns(pt->deadline);
+
+	dma_fence_put(fence);
+
+	if (copy_to_user((void __user *)arg, &data, sizeof(data)))
+		return -EFAULT;
+
+	return 0;
+}
+
 static long sw_sync_ioctl(struct file *file, unsigned int cmd,
 			  unsigned long arg)
 {
@@ -399,6 +454,9 @@ static long sw_sync_ioctl(struct file *file, unsigned int cmd,
 	case SW_SYNC_IOC_INC:
 		return sw_sync_ioctl_inc(obj, arg);
 
+	case SW_SYNC_GET_DEADLINE:
+		return sw_sync_ioctl_get_deadline(obj, arg);
+
 	default:
 		return -ENOTTY;
 	}
drivers/dma-buf/sync_debug.h +2 -0
index 6176e52ba2d7..2e0146d0bdbb 100644
@@ -55,11 +55,13 @@ static inline struct sync_timeline *dma_fence_parent(struct dma_fence *fence)
  * @base: base fence object
  * @link: link on the sync timeline's list
  * @node: node in the sync timeline's tree
+ * @deadline: the most recently set fence deadline
  */
 struct sync_pt {
 	struct dma_fence base;
 	struct list_head link;
 	struct rb_node node;
+	ktime_t deadline;
 };
 
 extern const struct file_operations sw_sync_debugfs_fops;
Signature · 1 line
2.39.1
author
#8 lore raw

PATCH v5 8/14 drm/scheduler: Add fence deadline support

In reply to Rob Clark

As the finished fence is the one that is exposed to userspace, and therefore the one that other operations, like atomic update, would block on, we need to propagate the deadline from from the finished fence to the actual hw fence.

v2: Split into drm_sched_fence_set_parent() (ckoenig)
v3: Ensure a thread calling drm_sched_fence_set_deadline_finished() sees

    fence->parent set before drm_sched_fence_set_parent() does this
    test_bit(DMA_FENCE_FLAG_HAS_DEADLINE_BIT).
---
 drivers/gpu/drm/scheduler/sched_fence.c | 46 +++++++++++++++++++++++++
 drivers/gpu/drm/scheduler/sched_main.c  |  2 +-
 include/drm/gpu_scheduler.h             |  8 +++++
 3 files changed, 55 insertions(+), 1 deletion(-)
drivers/gpu/drm/scheduler/sched_fence.c +46 -0
index 7fd869520ef2..43e2d4f5fe3b 100644
@@ -123,6 +123,37 @@ static void drm_sched_fence_release_finished(struct dma_fence *f)
 	dma_fence_put(&fence->scheduled);
 }
 
+static void drm_sched_fence_set_deadline_finished(struct dma_fence *f,
+						  ktime_t deadline)
+{
+	struct drm_sched_fence *fence = to_drm_sched_fence(f);
+	struct dma_fence *parent;
+	unsigned long flags;
+
+	spin_lock_irqsave(&fence->lock, flags);
+
+	/* If we already have an earlier deadline, keep it: */
+	if (test_bit(DMA_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags) &&
+	    ktime_before(fence->deadline, deadline)) {
+		spin_unlock_irqrestore(&fence->lock, flags);
+		return;
+	}
+
+	fence->deadline = deadline;
+	set_bit(DMA_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags);
+
+	spin_unlock_irqrestore(&fence->lock, flags);
+
+	/*
+	 * smp_load_aquire() to ensure that if we are racing another
+	 * thread calling drm_sched_fence_set_parent(), that we see
+	 * the parent set before it calls test_bit(HAS_DEADLINE_BIT)
+	 */
+	parent = smp_load_acquire(&fence->parent);
+	if (parent)
+		dma_fence_set_deadline(parent, deadline);
+}
+
 static const struct dma_fence_ops drm_sched_fence_ops_scheduled = {
 	.get_driver_name = drm_sched_fence_get_driver_name,
 	.get_timeline_name = drm_sched_fence_get_timeline_name,
@@ -133,6 +164,7 @@ static const struct dma_fence_ops drm_sched_fence_ops_finished = {
 	.get_driver_name = drm_sched_fence_get_driver_name,
 	.get_timeline_name = drm_sched_fence_get_timeline_name,
 	.release = drm_sched_fence_release_finished,
+	.set_deadline = drm_sched_fence_set_deadline_finished,
 };
 
 struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f)
@@ -147,6 +179,20 @@ struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f)
 }
 EXPORT_SYMBOL(to_drm_sched_fence);
 
+void drm_sched_fence_set_parent(struct drm_sched_fence *s_fence,
+				struct dma_fence *fence)
+{
+	/*
+	 * smp_store_release() to ensure another thread racing us
+	 * in drm_sched_fence_set_deadline_finished() sees the
+	 * fence's parent set before test_bit()
+	 */
+	smp_store_release(&s_fence->parent, dma_fence_get(fence));
+	if (test_bit(DMA_FENCE_FLAG_HAS_DEADLINE_BIT,
+		     &s_fence->finished.flags))
+		dma_fence_set_deadline(fence, s_fence->deadline);
+}
+
 struct drm_sched_fence *drm_sched_fence_alloc(struct drm_sched_entity *entity,
 					      void *owner)
 {
drivers/gpu/drm/scheduler/sched_main.c +1 -1
index 4e6ad6e122bc..007f98c48f8d 100644
@@ -1019,7 +1019,7 @@ static int drm_sched_main(void *param)
 		drm_sched_fence_scheduled(s_fence);
 
 		if (!IS_ERR_OR_NULL(fence)) {
-			s_fence->parent = dma_fence_get(fence);
+			drm_sched_fence_set_parent(s_fence, fence);
 			/* Drop for original kref_init of the fence */
 			dma_fence_put(fence);
 
include/drm/gpu_scheduler.h +8 -0
index 9db9e5e504ee..8b31a954a44d 100644
@@ -280,6 +280,12 @@ struct drm_sched_fence {
          */
 	struct dma_fence		finished;
 
+	/**
+	 * @deadline: deadline set on &drm_sched_fence.finished which
+	 * potentially needs to be propagated to &drm_sched_fence.parent
+	 */
+	ktime_t				deadline;
+
         /**
          * @parent: the fence returned by &drm_sched_backend_ops.run_job
          * when scheduling the job on hardware. We signal the
@@ -568,6 +574,8 @@ void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
 				   enum drm_sched_priority priority);
 bool drm_sched_entity_is_ready(struct drm_sched_entity *entity);
 
+void drm_sched_fence_set_parent(struct drm_sched_fence *s_fence,
+				struct dma_fence *fence);
 struct drm_sched_fence *drm_sched_fence_alloc(
 	struct drm_sched_entity *s_entity, void *owner);
 void drm_sched_fence_init(struct drm_sched_fence *fence,
Signature · 1 line
2.39.1
author
#9 lore raw

PATCH v5 9/14 drm/syncobj: Add deadline support for syncobj waits

In reply to Rob Clark

From: Rob Clark <[email protected]>

Add a new flag to let userspace provide a deadline as a hint for syncobj and timeline waits. This gives a hint to the driver signaling the backing fences about how soon userspace needs it to compete work, so it can addjust GPU frequency accordingly. An immediate deadline can be given to provide something equivalent to i915 "wait boost".

v2: Use absolute u64 ns value for deadline hint, drop cap and driver
feature flag in favor of allowing count_handles==0 as a way for userspace to probe kernel for support of new flag

---
 drivers/gpu/drm/drm_syncobj.c | 59 +++++++++++++++++++++++++++--------
 include/uapi/drm/drm.h        |  5 +++
 2 files changed, 51 insertions(+), 13 deletions(-)
drivers/gpu/drm/drm_syncobj.c +46 -13
index 0c2be8360525..4f9c3b3906f1 100644
@@ -973,7 +973,8 @@ static signed long drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
 						  uint32_t count,
 						  uint32_t flags,
 						  signed long timeout,
-						  uint32_t *idx)
+						  uint32_t *idx,
+						  ktime_t *deadline)
 {
 	struct syncobj_wait_entry *entries;
 	struct dma_fence *fence;
@@ -1053,6 +1054,15 @@ static signed long drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
 			drm_syncobj_fence_add_wait(syncobjs[i], &entries[i]);
 	}
 
+	if (deadline) {
+		for (i = 0; i < count; ++i) {
+			fence = entries[i].fence;
+			if (!fence)
+				continue;
+			dma_fence_set_deadline(fence, *deadline);
+		}
+	}
+
 	do {
 		set_current_state(TASK_INTERRUPTIBLE);
 
@@ -1151,7 +1161,8 @@ static int drm_syncobj_array_wait(struct drm_device *dev,
 				  struct drm_file *file_private,
 				  struct drm_syncobj_wait *wait,
 				  struct drm_syncobj_timeline_wait *timeline_wait,
-				  struct drm_syncobj **syncobjs, bool timeline)
+				  struct drm_syncobj **syncobjs, bool timeline,
+				  ktime_t *deadline)
 {
 	signed long timeout = 0;
 	uint32_t first = ~0;
@@ -1162,7 +1173,8 @@ static int drm_syncobj_array_wait(struct drm_device *dev,
 							 NULL,
 							 wait->count_handles,
 							 wait->flags,
-							 timeout, &first);
+							 timeout, &first,
+							 deadline);
 		if (timeout < 0)
 			return timeout;
 		wait->first_signaled = first;
@@ -1172,7 +1184,8 @@ static int drm_syncobj_array_wait(struct drm_device *dev,
 							 u64_to_user_ptr(timeline_wait->points),
 							 timeline_wait->count_handles,
 							 timeline_wait->flags,
-							 timeout, &first);
+							 timeout, &first,
+							 deadline);
 		if (timeout < 0)
 			return timeout;
 		timeline_wait->first_signaled = first;
@@ -1243,17 +1256,22 @@ drm_syncobj_wait_ioctl(struct drm_device *dev, void *data,
 {
 	struct drm_syncobj_wait *args = data;
 	struct drm_syncobj **syncobjs;
+	unsigned possible_flags;
+	ktime_t t, *tp = NULL;
 	int ret = 0;
 
 	if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
 		return -EOPNOTSUPP;
 
-	if (args->flags & ~(DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL |
-			    DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT))
+	possible_flags = DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL |
+			 DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT |
+			 DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE;
+
+	if (args->flags & ~possible_flags)
 		return -EINVAL;
 
 	if (args->count_handles == 0)
-		return -EINVAL;
+		return 0;
 
 	ret = drm_syncobj_array_find(file_private,
 				     u64_to_user_ptr(args->handles),
@@ -1262,8 +1280,13 @@ drm_syncobj_wait_ioctl(struct drm_device *dev, void *data,
 	if (ret < 0)
 		return ret;
 
+	if (args->flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE) {
+		t = ns_to_ktime(args->deadline_ns);
+		tp = &t;
+	}
+
 	ret = drm_syncobj_array_wait(dev, file_private,
-				     args, NULL, syncobjs, false);
+				     args, NULL, syncobjs, false, tp);
 
 	drm_syncobj_array_free(syncobjs, args->count_handles);
 
@@ -1276,18 +1299,23 @@ drm_syncobj_timeline_wait_ioctl(struct drm_device *dev, void *data,
 {
 	struct drm_syncobj_timeline_wait *args = data;
 	struct drm_syncobj **syncobjs;
+	unsigned possible_flags;
+	ktime_t t, *tp = NULL;
 	int ret = 0;
 
 	if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
 		return -EOPNOTSUPP;
 
-	if (args->flags & ~(DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL |
-			    DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT |
-			    DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE))
+	possible_flags = DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL |
+			 DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT |
+			 DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE |
+			 DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE;
+
+	if (args->flags & ~possible_flags)
 		return -EINVAL;
 
 	if (args->count_handles == 0)
-		return -EINVAL;
+		return -0;
 
 	ret = drm_syncobj_array_find(file_private,
 				     u64_to_user_ptr(args->handles),
@@ -1296,8 +1324,13 @@ drm_syncobj_timeline_wait_ioctl(struct drm_device *dev, void *data,
 	if (ret < 0)
 		return ret;
 
+	if (args->flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE) {
+		t = ns_to_ktime(args->deadline_ns);
+		tp = &t;
+	}
+
 	ret = drm_syncobj_array_wait(dev, file_private,
-				     NULL, args, syncobjs, true);
+				     NULL, args, syncobjs, true, tp);
 
 	drm_syncobj_array_free(syncobjs, args->count_handles);
 
include/uapi/drm/drm.h +5 -0
index 642808520d92..aefc8cc743e0 100644
@@ -887,6 +887,7 @@ struct drm_syncobj_transfer {
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL (1 << 0)
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT (1 << 1)
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE (1 << 2) /* wait for time point to become available */
+#define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE (1 << 3) /* set fence deadline based to deadline_nsec/sec */
 struct drm_syncobj_wait {
 	__u64 handles;
 	/* absolute timeout */
@@ -895,6 +896,8 @@ struct drm_syncobj_wait {
 	__u32 flags;
 	__u32 first_signaled; /* only valid when not waiting all */
 	__u32 pad;
+	/* Deadline hint to set on backing fence(s) in CLOCK_MONOTONIC: */
+	__u64 deadline_ns;
 };
 
 struct drm_syncobj_timeline_wait {
@@ -907,6 +910,8 @@ struct drm_syncobj_timeline_wait {
 	__u32 flags;
 	__u32 first_signaled; /* only valid when not waiting all */
 	__u32 pad;
+	/* Deadline hint to set on backing fence(s) in CLOCK_MONOTONIC: */
+	__u64 deadline_ns;
 };
 
 
Signature · 1 line
2.39.1
#10 lore raw

Re: [PATCH v5 09/14] drm/syncobj: Add deadline support for syncobj waits

Quoted 17 lines · On Mon, 20 Feb 2023 12:18:56 -0800 Rob Clark <[email protected]> wrote:

From: Rob Clark <[email protected]>

Add a new flag to let userspace provide a deadline as a hint for syncobj and timeline waits. This gives a hint to the driver signaling the backing fences about how soon userspace needs it to compete work, so it can addjust GPU frequency accordingly. An immediate deadline can be given to provide something equivalent to i915 "wait boost".

v2: Use absolute u64 ns value for deadline hint, drop cap and driver
feature flag in favor of allowing count_handles==0 as a way for userspace to probe kernel for support of new flag

---
 drivers/gpu/drm/drm_syncobj.c | 59 +++++++++++++++++++++++++++--------
 include/uapi/drm/drm.h        |  5 +++
 2 files changed, 51 insertions(+), 13 deletions(-)

...

include/uapi/drm/drm.h struct drm_syncobj_transfer { · line 890

Quoted 9 lines
include/uapi/drm/drm.h +1 -0
index 642808520d92..aefc8cc743e0 100644
@@ -887,6 +887,7 @@ struct drm_syncobj_transfer {
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL (1 << 0)
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT (1 << 1)
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE (1 << 2) /* wait for time point to become available */
+#define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE (1 << 3) /* set fence deadline based to deadline_nsec/sec */

Hi,

where is the UAPI documentation explaining what is a "fence deadline" and what setting it does here?

btw. no nsec/sec anymore.

Thanks,
pq

Quoted 21 lines
include/uapi/drm/drm.h +4 -0
 struct drm_syncobj_wait {
 	__u64 handles;
 	/* absolute timeout */
@@ -895,6 +896,8 @@ struct drm_syncobj_wait {
 	__u32 flags;
 	__u32 first_signaled; /* only valid when not waiting all */
 	__u32 pad;
+	/* Deadline hint to set on backing fence(s) in CLOCK_MONOTONIC: */
+	__u64 deadline_ns;
 };
 
 struct drm_syncobj_timeline_wait {
@@ -907,6 +910,8 @@ struct drm_syncobj_timeline_wait {
 	__u32 flags;
 	__u32 first_signaled; /* only valid when not waiting all */
 	__u32 pad;
+	/* Deadline hint to set on backing fence(s) in CLOCK_MONOTONIC: */
+	__u64 deadline_ns;
 };
 
 
author
#11 lore raw

Re: [PATCH v5 09/14] drm/syncobj: Add deadline support for syncobj waits

Quoted 36 lines · Pekka Paalanen
Quoted 17 lines · On Mon, 20 Feb 2023 12:18:56 -0800 Rob Clark <[email protected]> wrote:

From: Rob Clark <[email protected]>

Add a new flag to let userspace provide a deadline as a hint for syncobj and timeline waits. This gives a hint to the driver signaling the backing fences about how soon userspace needs it to compete work, so it can addjust GPU frequency accordingly. An immediate deadline can be given to provide something equivalent to i915 "wait boost".

v2: Use absolute u64 ns value for deadline hint, drop cap and driver
feature flag in favor of allowing count_handles==0 as a way for userspace to probe kernel for support of new flag

---
 drivers/gpu/drm/drm_syncobj.c | 59 +++++++++++++++++++++++++++--------
 include/uapi/drm/drm.h        |  5 +++
 2 files changed, 51 insertions(+), 13 deletions(-)

...

include/uapi/drm/drm.h struct drm_syncobj_transfer { · line 890

Quoted 9 lines
include/uapi/drm/drm.h +1 -0
index 642808520d92..aefc8cc743e0 100644
@@ -887,6 +887,7 @@ struct drm_syncobj_transfer {
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL (1 << 0)
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT (1 << 1)
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE (1 << 2) /* wait for time point to become available */
+#define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE (1 << 3) /* set fence deadline based to deadline_nsec/sec */

Hi,

Quoted 2 lines

where is the UAPI documentation explaining what is a "fence deadline" and what setting it does here?

It's with the rest of the drm_syncobj UAPI docs ;-)

BR,
-R

Quoted 29 lines

btw. no nsec/sec anymore.

Thanks,
pq

Quoted 21 lines
include/uapi/drm/drm.h +4 -0
 struct drm_syncobj_wait {
      __u64 handles;
      /* absolute timeout */
@@ -895,6 +896,8 @@ struct drm_syncobj_wait {
      __u32 flags;
      __u32 first_signaled; /* only valid when not waiting all */
      __u32 pad;
+     /* Deadline hint to set on backing fence(s) in CLOCK_MONOTONIC: */
+     __u64 deadline_ns;
 };
 
 struct drm_syncobj_timeline_wait {
@@ -907,6 +910,8 @@ struct drm_syncobj_timeline_wait {
      __u32 flags;
      __u32 first_signaled; /* only valid when not waiting all */
      __u32 pad;
+     /* Deadline hint to set on backing fence(s) in CLOCK_MONOTONIC: */
+     __u64 deadline_ns;
 };
 
 
#12 lore raw

Re: [PATCH v5 09/14] drm/syncobj: Add deadline support for syncobj waits

Quoted 37 lines · On Tue, 21 Feb 2023 09:25:18 -0800 Rob Clark <[email protected]> wrote:
Quoted 36 lines · Pekka Paalanen
Quoted 17 lines · On Mon, 20 Feb 2023 12:18:56 -0800 Rob Clark <[email protected]> wrote:

From: Rob Clark <[email protected]>

Add a new flag to let userspace provide a deadline as a hint for syncobj and timeline waits. This gives a hint to the driver signaling the backing fences about how soon userspace needs it to compete work, so it can addjust GPU frequency accordingly. An immediate deadline can be given to provide something equivalent to i915 "wait boost".

v2: Use absolute u64 ns value for deadline hint, drop cap and driver
feature flag in favor of allowing count_handles==0 as a way for userspace to probe kernel for support of new flag

---
 drivers/gpu/drm/drm_syncobj.c | 59 +++++++++++++++++++++++++++--------
 include/uapi/drm/drm.h        |  5 +++
 2 files changed, 51 insertions(+), 13 deletions(-)  

...

include/uapi/drm/drm.h struct drm_syncobj_transfer { · line 890

Quoted 9 lines
include/uapi/drm/drm.h +1 -0
index 642808520d92..aefc8cc743e0 100644
@@ -887,6 +887,7 @@ struct drm_syncobj_transfer {
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL (1 << 0)
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT (1 << 1)
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE (1 << 2) /* wait for time point to become available */
+#define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE (1 << 3) /* set fence deadline based to deadline_nsec/sec */  

Hi,

Quoted 4 lines
Quoted 2 lines

where is the UAPI documentation explaining what is a "fence deadline" and what setting it does here?

It's with the rest of the drm_syncobj UAPI docs ;-)

Is that https://www.kernel.org/doc/html/latest/driver-api/dma-buf.html#dma-fence-uabi-sync-file ?

That whole page never mentions e.g. WAIT_AVAILABLE, so at least the flags are not there. Does not mention syncobj_wait either.

I could ask where the real non-IGT userspace is or the plan for it, too, since this is new DRM UAPI.

Thanks,
pq

Quoted 33 lines

BR,
-R

Quoted 29 lines

btw. no nsec/sec anymore.

Thanks,
pq

Quoted 21 lines
include/uapi/drm/drm.h +4 -0
 struct drm_syncobj_wait {
      __u64 handles;
      /* absolute timeout */
@@ -895,6 +896,8 @@ struct drm_syncobj_wait {
      __u32 flags;
      __u32 first_signaled; /* only valid when not waiting all */
      __u32 pad;
+     /* Deadline hint to set on backing fence(s) in CLOCK_MONOTONIC: */
+     __u64 deadline_ns;
 };
 
 struct drm_syncobj_timeline_wait {
@@ -907,6 +910,8 @@ struct drm_syncobj_timeline_wait {
      __u32 flags;
      __u32 first_signaled; /* only valid when not waiting all */
      __u32 pad;
+     /* Deadline hint to set on backing fence(s) in CLOCK_MONOTONIC: */
+     __u64 deadline_ns;
 };
 
 
maintainer
#13 lore raw

Re: [PATCH v5 09/14] drm/syncobj: Add deadline support for syncobj waits

Quoted 43 lines · Pekka Paalanen
Quoted 40 lines · On Tue, 21 Feb 2023 09:25:18 -0800 Rob Clark <[email protected]> wrote:
Quoted 38 lines · Pekka Paalanen
Quoted 17 lines · On Mon, 20 Feb 2023 12:18:56 -0800 Rob Clark <[email protected]> wrote:

From: Rob Clark <[email protected]>

Add a new flag to let userspace provide a deadline as a hint for syncobj and timeline waits. This gives a hint to the driver signaling the backing fences about how soon userspace needs it to compete work, so it can addjust GPU frequency accordingly. An immediate deadline can be given to provide something equivalent to i915 "wait boost".

v2: Use absolute u64 ns value for deadline hint, drop cap and driver
feature flag in favor of allowing count_handles==0 as a way for userspace to probe kernel for support of new flag

---
 drivers/gpu/drm/drm_syncobj.c | 59 +++++++++++++++++++++++++++--------
 include/uapi/drm/drm.h        |  5 +++
 2 files changed, 51 insertions(+), 13 deletions(-)  

...

include/uapi/drm/drm.h struct drm_syncobj_transfer { · line 890

Quoted 9 lines
include/uapi/drm/drm.h +1 -0
index 642808520d92..aefc8cc743e0 100644
@@ -887,6 +887,7 @@ struct drm_syncobj_transfer {
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL (1 << 0)
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT (1 << 1)
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE (1 << 2) /* wait for time point to become available */
+#define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE (1 << 3) /* set fence deadline based to deadline_nsec/sec */  

Hi,

where is the UAPI documentation explaining what is a "fence deadline" and what setting it does here?

Quoted 6 lines
Quoted 1 line

It's with the rest of the drm_syncobj UAPI docs ;-)

Is that https://www.kernel.org/doc/html/latest/driver-api/dma-buf.html#dma-fence-uabi-sync-file ?

That whole page never mentions e.g. WAIT_AVAILABLE, so at least the flags are not there. Does not mention syncobj_wait either.

probably this:
https://docs.kernel.org/gpu/drm-mm.html

the new one needs to be added there as well.

Quoted 3 lines

I could ask where the real non-IGT userspace is or the plan for it, too, since this is new DRM UAPI.

yeap, it looks like we need to close on this...
https://gitlab.freedesktop.org/drm/intel/-/issues/8014

I confess I got lost on the many discussions and on how this will be used. Is mesa going to set the deadline based on the vk priority?

Will this continue to be internal? I didn't get the broader picture I'm afraid...

Quoted 39 lines

Thanks,
pq

Quoted 33 lines

BR,
-R

Quoted 29 lines

btw. no nsec/sec anymore.

Thanks,
pq

Quoted 21 lines
include/uapi/drm/drm.h +4 -0
 struct drm_syncobj_wait {
      __u64 handles;
      /* absolute timeout */
@@ -895,6 +896,8 @@ struct drm_syncobj_wait {
      __u32 flags;
      __u32 first_signaled; /* only valid when not waiting all */
      __u32 pad;
+     /* Deadline hint to set on backing fence(s) in CLOCK_MONOTONIC: */
+     __u64 deadline_ns;
 };
 
 struct drm_syncobj_timeline_wait {
@@ -907,6 +910,8 @@ struct drm_syncobj_timeline_wait {
      __u32 flags;
      __u32 first_signaled; /* only valid when not waiting all */
      __u32 pad;
+     /* Deadline hint to set on backing fence(s) in CLOCK_MONOTONIC: */
+     __u64 deadline_ns;
 };
 
 
author
#14 lore raw

Re: [PATCH v5 09/14] drm/syncobj: Add deadline support for syncobj waits

Quoted 45 lines · Rodrigo Vivi
Quoted 43 lines · Pekka Paalanen
Quoted 40 lines · On Tue, 21 Feb 2023 09:25:18 -0800 Rob Clark <[email protected]> wrote:
Quoted 38 lines · Pekka Paalanen
Quoted 17 lines · On Mon, 20 Feb 2023 12:18:56 -0800 Rob Clark <[email protected]> wrote:

From: Rob Clark <[email protected]>

Add a new flag to let userspace provide a deadline as a hint for syncobj and timeline waits. This gives a hint to the driver signaling the backing fences about how soon userspace needs it to compete work, so it can addjust GPU frequency accordingly. An immediate deadline can be given to provide something equivalent to i915 "wait boost".

v2: Use absolute u64 ns value for deadline hint, drop cap and driver
feature flag in favor of allowing count_handles==0 as a way for userspace to probe kernel for support of new flag

---
 drivers/gpu/drm/drm_syncobj.c | 59 +++++++++++++++++++++++++++--------
 include/uapi/drm/drm.h        |  5 +++
 2 files changed, 51 insertions(+), 13 deletions(-)

...

include/uapi/drm/drm.h struct drm_syncobj_transfer { · line 890

Quoted 9 lines
include/uapi/drm/drm.h +1 -0
index 642808520d92..aefc8cc743e0 100644
@@ -887,6 +887,7 @@ struct drm_syncobj_transfer {
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL (1 << 0)
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT (1 << 1)
 #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE (1 << 2) /* wait for time point to become available */
+#define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE (1 << 3) /* set fence deadline based to deadline_nsec/sec */

Hi,

where is the UAPI documentation explaining what is a "fence deadline" and what setting it does here?

Quoted 6 lines
Quoted 6 lines
Quoted 1 line

It's with the rest of the drm_syncobj UAPI docs ;-)

Is that https://www.kernel.org/doc/html/latest/driver-api/dma-buf.html#dma-fence-uabi-sync-file ?

That whole page never mentions e.g. WAIT_AVAILABLE, so at least the flags are not there. Does not mention syncobj_wait either.

Sorry, that was a snarky reference to thin UABI docs about syncobj. The kernel side of it is better documented.

Quoted 9 lines

probably this:
https://docs.kernel.org/gpu/drm-mm.html

the new one needs to be added there as well.

Quoted 3 lines

I could ask where the real non-IGT userspace is or the plan for it, too, since this is new DRM UAPI.

Quoted 8 lines

yeap, it looks like we need to close on this...
https://gitlab.freedesktop.org/drm/intel/-/issues/8014

I confess I got lost on the many discussions and on how this will be used. Is mesa going to set the deadline based on the vk priority?

Will this continue to be internal? I didn't get the broader picture I'm afraid...

Yes, the plan is to use it from mesa vk-common helpers (and elsewhere in mesa if needed). There is a separate discussion[1] about limiting/allowing boost (perhaps based on ctx flag or cgroups) but that is more about how drivers react to the deadline hint. The immediate goal of this patch is just to fix the regression mentioned in that gitlab issue when using syncobj waits instead of DRM_IOCTL_I915_GEM_WAIT

BR,
-R

[1] https://www.spinics.net/lists/dri-devel/msg383075.html

Quoted 41 lines
Quoted 39 lines

Thanks,
pq

Quoted 33 lines

BR,
-R

Quoted 29 lines

btw. no nsec/sec anymore.

Thanks,
pq

Quoted 21 lines
include/uapi/drm/drm.h +4 -0
 struct drm_syncobj_wait {
      __u64 handles;
      /* absolute timeout */
@@ -895,6 +896,8 @@ struct drm_syncobj_wait {
      __u32 flags;
      __u32 first_signaled; /* only valid when not waiting all */
      __u32 pad;
+     /* Deadline hint to set on backing fence(s) in CLOCK_MONOTONIC: */
+     __u64 deadline_ns;
 };
 
 struct drm_syncobj_timeline_wait {
@@ -907,6 +910,8 @@ struct drm_syncobj_timeline_wait {
      __u32 flags;
      __u32 first_signaled; /* only valid when not waiting all */
      __u32 pad;
+     /* Deadline hint to set on backing fence(s) in CLOCK_MONOTONIC: */
+     __u64 deadline_ns;
 };
 
 
author
#15 lore raw

PATCH v5 10/14 drm/vblank: Add helper to get next vblank time

In reply to Rob Clark

From: Rob Clark <[email protected]>

Will be used in the next commit to set a deadline on fences that an atomic update is waiting on.

---
 drivers/gpu/drm/drm_vblank.c | 32 ++++++++++++++++++++++++++++++++
 include/drm/drm_vblank.h     |  1 +
 2 files changed, 33 insertions(+)
drivers/gpu/drm/drm_vblank.c +32 -0
index 2ff31717a3de..caf25ebb34c5 100644
@@ -980,6 +980,38 @@ u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc,
 }
 EXPORT_SYMBOL(drm_crtc_vblank_count_and_time);
 
+/**
+ * drm_crtc_next_vblank_time - calculate the time of the next vblank
+ * @crtc: the crtc for which to calculate next vblank time
+ * @vblanktime: pointer to time to receive the next vblank timestamp.
+ *
+ * Calculate the expected time of the next vblank based on time of previous
+ * vblank and frame duration
+ */
+int drm_crtc_next_vblank_time(struct drm_crtc *crtc, ktime_t *vblanktime)
+{
+	unsigned int pipe = drm_crtc_index(crtc);
+	struct drm_vblank_crtc *vblank = &crtc->dev->vblank[pipe];
+	u64 count;
+
+	if (!vblank->framedur_ns)
+		return -EINVAL;
+
+	count = drm_vblank_count_and_time(crtc->dev, pipe, vblanktime);
+
+	/*
+	 * If we don't get a valid count, then we probably also don't
+	 * have a valid time:
+	 */
+	if (!count)
+		return -EINVAL;
+
+	*vblanktime = ktime_add(*vblanktime, ns_to_ktime(vblank->framedur_ns));
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_crtc_next_vblank_time);
+
 static void send_vblank_event(struct drm_device *dev,
 		struct drm_pending_vblank_event *e,
 		u64 seq, ktime_t now)
include/drm/drm_vblank.h +1 -0
index 733a3e2d1d10..a63bc2c92f3c 100644
@@ -230,6 +230,7 @@ bool drm_dev_has_vblank(const struct drm_device *dev);
 u64 drm_crtc_vblank_count(struct drm_crtc *crtc);
 u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc,
 				   ktime_t *vblanktime);
+int drm_crtc_next_vblank_time(struct drm_crtc *crtc, ktime_t *vblanktime);
 void drm_crtc_send_vblank_event(struct drm_crtc *crtc,
 			       struct drm_pending_vblank_event *e);
 void drm_crtc_arm_vblank_event(struct drm_crtc *crtc,
Signature · 1 line
2.39.1
author
#16 lore raw

PATCH v5 11/14 drm/atomic-helper: Set fence deadline for vblank

In reply to Rob Clark

From: Rob Clark <[email protected]>

For an atomic commit updating a single CRTC (ie. a pageflip) calculate the next vblank time, and inform the fence(s) of that deadline.

v2: Comment typo fix (danvet)

---
 drivers/gpu/drm/drm_atomic_helper.c | 36 +++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
drivers/gpu/drm/drm_atomic_helper.c +36 -0
index d579fd8f7cb8..35a4dc714920 100644
@@ -1511,6 +1511,40 @@ void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
 }
 EXPORT_SYMBOL(drm_atomic_helper_commit_modeset_enables);
 
+/*
+ * For atomic updates which touch just a single CRTC, calculate the time of the
+ * next vblank, and inform all the fences of the deadline.
+ */
+static void set_fence_deadline(struct drm_device *dev,
+			       struct drm_atomic_state *state)
+{
+	struct drm_crtc *crtc, *wait_crtc = NULL;
+	struct drm_crtc_state *new_crtc_state;
+	struct drm_plane *plane;
+	struct drm_plane_state *new_plane_state;
+	ktime_t vbltime;
+	int i;
+
+	for_each_new_crtc_in_state (state, crtc, new_crtc_state, i) {
+		if (wait_crtc)
+			return;
+		wait_crtc = crtc;
+	}
+
+	/* If no CRTCs updated, then nothing to do: */
+	if (!wait_crtc)
+		return;
+
+	if (drm_crtc_next_vblank_time(wait_crtc, &vbltime))
+		return;
+
+	for_each_new_plane_in_state (state, plane, new_plane_state, i) {
+		if (!new_plane_state->fence)
+			continue;
+		dma_fence_set_deadline(new_plane_state->fence, vbltime);
+	}
+}
+
 /**
  * drm_atomic_helper_wait_for_fences - wait for fences stashed in plane state
  * @dev: DRM device
@@ -1540,6 +1574,8 @@ int drm_atomic_helper_wait_for_fences(struct drm_device *dev,
 	struct drm_plane_state *new_plane_state;
 	int i, ret;
 
+	set_fence_deadline(dev, state);
+
 	for_each_new_plane_in_state(state, plane, new_plane_state, i) {
 		if (!new_plane_state->fence)
 			continue;
Signature · 1 line
2.39.1
author
#17 lore raw

PATCH v5 12/14 drm/msm: Add deadline based boost support

In reply to Rob Clark

From: Rob Clark <[email protected]>

Track the nearest deadline on a fence timeline and set a timer to expire shortly before to trigger boost if the fence has not yet been signaled.

v2: rebase

---
 drivers/gpu/drm/msm/msm_fence.c | 74 +++++++++++++++++++++++++++++++++
 drivers/gpu/drm/msm/msm_fence.h | 20 +++++++++
 2 files changed, 94 insertions(+)
drivers/gpu/drm/msm/msm_fence.c +74 -0
index 56641408ea74..51b461f32103 100644
@@ -8,6 +8,35 @@
 
 #include "msm_drv.h"
 #include "msm_fence.h"
+#include "msm_gpu.h"
+
+static struct msm_gpu *fctx2gpu(struct msm_fence_context *fctx)
+{
+	struct msm_drm_private *priv = fctx->dev->dev_private;
+	return priv->gpu;
+}
+
+static enum hrtimer_restart deadline_timer(struct hrtimer *t)
+{
+	struct msm_fence_context *fctx = container_of(t,
+			struct msm_fence_context, deadline_timer);
+
+	kthread_queue_work(fctx2gpu(fctx)->worker, &fctx->deadline_work);
+
+	return HRTIMER_NORESTART;
+}
+
+static void deadline_work(struct kthread_work *work)
+{
+	struct msm_fence_context *fctx = container_of(work,
+			struct msm_fence_context, deadline_work);
+
+	/* If deadline fence has already passed, nothing to do: */
+	if (msm_fence_completed(fctx, fctx->next_deadline_fence))
+		return;
+
+	msm_devfreq_boost(fctx2gpu(fctx), 2);
+}
 
 
 struct msm_fence_context *
@@ -36,6 +65,13 @@ msm_fence_context_alloc(struct drm_device *dev, volatile uint32_t *fenceptr,
 	fctx->completed_fence = fctx->last_fence;
 	*fctx->fenceptr = fctx->last_fence;
 
+	hrtimer_init(&fctx->deadline_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+	fctx->deadline_timer.function = deadline_timer;
+
+	kthread_init_work(&fctx->deadline_work, deadline_work);
+
+	fctx->next_deadline = ktime_get();
+
 	return fctx;
 }
 
@@ -62,6 +98,8 @@ void msm_update_fence(struct msm_fence_context *fctx, uint32_t fence)
 	spin_lock_irqsave(&fctx->spinlock, flags);
 	if (fence_after(fence, fctx->completed_fence))
 		fctx->completed_fence = fence;
+	if (msm_fence_completed(fctx, fctx->next_deadline_fence))
+		hrtimer_cancel(&fctx->deadline_timer);
 	spin_unlock_irqrestore(&fctx->spinlock, flags);
 }
 
@@ -92,10 +130,46 @@ static bool msm_fence_signaled(struct dma_fence *fence)
 	return msm_fence_completed(f->fctx, f->base.seqno);
 }
 
+static void msm_fence_set_deadline(struct dma_fence *fence, ktime_t deadline)
+{
+	struct msm_fence *f = to_msm_fence(fence);
+	struct msm_fence_context *fctx = f->fctx;
+	unsigned long flags;
+	ktime_t now;
+
+	spin_lock_irqsave(&fctx->spinlock, flags);
+	now = ktime_get();
+
+	if (ktime_after(now, fctx->next_deadline) ||
+			ktime_before(deadline, fctx->next_deadline)) {
+		fctx->next_deadline = deadline;
+		fctx->next_deadline_fence =
+			max(fctx->next_deadline_fence, (uint32_t)fence->seqno);
+
+		/*
+		 * Set timer to trigger boost 3ms before deadline, or
+		 * if we are already less than 3ms before the deadline
+		 * schedule boost work immediately.
+		 */
+		deadline = ktime_sub(deadline, ms_to_ktime(3));
+
+		if (ktime_after(now, deadline)) {
+			kthread_queue_work(fctx2gpu(fctx)->worker,
+					&fctx->deadline_work);
+		} else {
+			hrtimer_start(&fctx->deadline_timer, deadline,
+					HRTIMER_MODE_ABS);
+		}
+	}
+
+	spin_unlock_irqrestore(&fctx->spinlock, flags);
+}
+
 static const struct dma_fence_ops msm_fence_ops = {
 	.get_driver_name = msm_fence_get_driver_name,
 	.get_timeline_name = msm_fence_get_timeline_name,
 	.signaled = msm_fence_signaled,
+	.set_deadline = msm_fence_set_deadline,
 };
 
 struct dma_fence *
drivers/gpu/drm/msm/msm_fence.h +20 -0
index 7f1798c54cd1..cdaebfb94f5c 100644
@@ -52,6 +52,26 @@ struct msm_fence_context {
 	volatile uint32_t *fenceptr;
 
 	spinlock_t spinlock;
+
+	/*
+	 * TODO this doesn't really deal with multiple deadlines, like
+	 * if userspace got multiple frames ahead.. OTOH atomic updates
+	 * don't queue, so maybe that is ok
+	 */
+
+	/** next_deadline: Time of next deadline */
+	ktime_t next_deadline;
+
+	/**
+	 * next_deadline_fence:
+	 *
+	 * Fence value for next pending deadline.  The deadline timer is
+	 * canceled when this fence is signaled.
+	 */
+	uint32_t next_deadline_fence;
+
+	struct hrtimer deadline_timer;
+	struct kthread_work deadline_work;
 };
 
 struct msm_fence_context * msm_fence_context_alloc(struct drm_device *dev,
Signature · 1 line
2.39.1
author
#18 lore raw

PATCH v5 13/14 drm/msm: Add wait-boost support

In reply to Rob Clark

From: Rob Clark <[email protected]>

Add a way for various userspace waits to signal urgency.

---
 drivers/gpu/drm/msm/msm_drv.c | 12 ++++++++----
 drivers/gpu/drm/msm/msm_gem.c |  5 +++++
 include/uapi/drm/msm_drm.h    | 14 ++++++++++++--
 3 files changed, 25 insertions(+), 6 deletions(-)
drivers/gpu/drm/msm/msm_drv.c +8 -4
index aca48c868c14..f6764a86b2da 100644
@@ -46,6 +46,7 @@
  * - 1.8.0 - Add MSM_BO_CACHED_COHERENT for supported GPUs (a6xx)
  * - 1.9.0 - Add MSM_SUBMIT_FENCE_SN_IN
  * - 1.10.0 - Add MSM_SUBMIT_BO_NO_IMPLICIT
+ * - 1.11.0 - Add wait boost (MSM_WAIT_FENCE_BOOST, MSM_PREP_BOOST)
  */
 #define MSM_VERSION_MAJOR	1
 #define MSM_VERSION_MINOR	10
@@ -899,7 +900,7 @@ static int msm_ioctl_gem_info(struct drm_device *dev, void *data,
 }
 
 static int wait_fence(struct msm_gpu_submitqueue *queue, uint32_t fence_id,
-		      ktime_t timeout)
+		      ktime_t timeout, uint32_t flags)
 {
 	struct dma_fence *fence;
 	int ret;
@@ -929,6 +930,9 @@ static int wait_fence(struct msm_gpu_submitqueue *queue, uint32_t fence_id,
 	if (!fence)
 		return 0;
 
+	if (flags & MSM_WAIT_FENCE_BOOST)
+		dma_fence_set_deadline(fence, ktime_get());
+
 	ret = dma_fence_wait_timeout(fence, true, timeout_to_jiffies(&timeout));
 	if (ret == 0) {
 		ret = -ETIMEDOUT;
@@ -949,8 +953,8 @@ static int msm_ioctl_wait_fence(struct drm_device *dev, void *data,
 	struct msm_gpu_submitqueue *queue;
 	int ret;
 
-	if (args->pad) {
-		DRM_ERROR("invalid pad: %08x\n", args->pad);
+	if (args->flags & ~MSM_WAIT_FENCE_FLAGS) {
+		DRM_ERROR("invalid flags: %08x\n", args->flags);
 		return -EINVAL;
 	}
 
@@ -961,7 +965,7 @@ static int msm_ioctl_wait_fence(struct drm_device *dev, void *data,
 	if (!queue)
 		return -ENOENT;
 
-	ret = wait_fence(queue, args->fence, to_ktime(args->timeout));
+	ret = wait_fence(queue, args->fence, to_ktime(args->timeout), args->flags);
 
 	msm_submitqueue_put(queue);
 
drivers/gpu/drm/msm/msm_gem.c +5 -0
index 1dee0d18abbb..dd4a0d773f6e 100644
@@ -846,6 +846,11 @@ int msm_gem_cpu_prep(struct drm_gem_object *obj, uint32_t op, ktime_t *timeout)
 		op & MSM_PREP_NOSYNC ? 0 : timeout_to_jiffies(timeout);
 	long ret;
 
+	if (op & MSM_PREP_BOOST) {
+		dma_resv_set_deadline(obj->resv, dma_resv_usage_rw(write),
+				      ktime_get());
+	}
+
 	ret = dma_resv_wait_timeout(obj->resv, dma_resv_usage_rw(write),
 				    true,  remain);
 	if (ret == 0)
include/uapi/drm/msm_drm.h +12 -2
index 329100016e7c..dbf0d6f43fa9 100644
@@ -151,8 +151,13 @@ struct drm_msm_gem_info {
 #define MSM_PREP_READ        0x01
 #define MSM_PREP_WRITE       0x02
 #define MSM_PREP_NOSYNC      0x04
+#define MSM_PREP_BOOST       0x08
 
-#define MSM_PREP_FLAGS       (MSM_PREP_READ | MSM_PREP_WRITE | MSM_PREP_NOSYNC)
+#define MSM_PREP_FLAGS       (MSM_PREP_READ | \
+			      MSM_PREP_WRITE | \
+			      MSM_PREP_NOSYNC | \
+			      MSM_PREP_BOOST | \
+			      0)
 
 struct drm_msm_gem_cpu_prep {
 	__u32 handle;         /* in */
@@ -286,6 +291,11 @@ struct drm_msm_gem_submit {
 
 };
 
+#define MSM_WAIT_FENCE_BOOST	0x00000001
+#define MSM_WAIT_FENCE_FLAGS	( \
+		MSM_WAIT_FENCE_BOOST | \
+		0)
+
 /* The normal way to synchronize with the GPU is just to CPU_PREP on
  * a buffer if you need to access it from the CPU (other cmdstream
  * submission from same or other contexts, PAGE_FLIP ioctl, etc, all
@@ -295,7 +305,7 @@ struct drm_msm_gem_submit {
  */
 struct drm_msm_wait_fence {
 	__u32 fence;          /* in */
-	__u32 pad;
+	__u32 flags;          /* in, bitmask of MSM_WAIT_FENCE_x */
 	struct drm_msm_timespec timeout;   /* in */
 	__u32 queueid;         /* in, submitqueue id */
 };
Signature · 1 line
2.39.1
author
#19 lore raw

PATCH v5 14/14 drm/i915: Add deadline based boost support

In reply to Rob Clark

From: Rob Clark <[email protected]>

v2: rebase

---
 drivers/gpu/drm/i915/i915_request.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
drivers/gpu/drm/i915/i915_request.c +20 -0
index 7503dcb9043b..44491e7e214c 100644
@@ -97,6 +97,25 @@ static bool i915_fence_enable_signaling(struct dma_fence *fence)
 	return i915_request_enable_breadcrumb(to_request(fence));
 }
 
+static void i915_fence_set_deadline(struct dma_fence *fence, ktime_t deadline)
+{
+	struct i915_request *rq = to_request(fence);
+
+	if (i915_request_completed(rq))
+		return;
+
+	if (i915_request_started(rq))
+		return;
+
+	/*
+	 * TODO something more clever for deadlines that are in the
+	 * future.  I think probably track the nearest deadline in
+	 * rq->timeline and set timer to trigger boost accordingly?
+	 */
+
+	intel_rps_boost(rq);
+}
+
 static signed long i915_fence_wait(struct dma_fence *fence,
 				   bool interruptible,
 				   signed long timeout)
@@ -182,6 +201,7 @@ const struct dma_fence_ops i915_fence_ops = {
 	.signaled = i915_fence_signaled,
 	.wait = i915_fence_wait,
 	.release = i915_fence_release,
+	.set_deadline = i915_fence_set_deadline,
 };
 
 static void irq_execute_cb(struct irq_work *wrk)
Signature · 1 line
2.39.1