From: John Harrison <John.C.Harrison@xxxxxxxxx>
When requesting that all GPU work is completed, it is now necessary to
get the scheduler involved in order to flush out work that queued and
not yet submitted.
v2: Updated to add support for flushing the scheduler queue by time
stamp rather than just doing a blanket flush.
v3: Moved submit_max_priority() to this patch from an earlier patch
is it is no longer required in the other.
v4: Corrected the format of a comment to keep the style checker happy.
Downgraded a BUG_ON to a WARN_ON as the latter is preferred.
v5: Shuffled functions around to remove forward prototypes, removed
similarly offensive white space and added documentation. Re-worked the
mutex locking around the submit function. [Joonas Lahtinen]
Used lighter weight spinlocks.
v6: Updated to newer nightly (lots of ring -> engine renaming).
Added 'for_each_scheduler_node()' helper macro. Updated to use
'to_i915()' instead of dev_private. Converted all enum labels to
uppercase. [review feedback from Joonas Lahtinen]
For: VIZ-1587
Signed-off-by: John Harrison <John.C.Harrison@xxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem.c | 22 +++++
drivers/gpu/drm/i915/i915_scheduler.c | 178 ++++++++++++++++++++++++++++++++++
drivers/gpu/drm/i915/i915_scheduler.h | 3 +
3 files changed, 203 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 5fb4472..3ee0283 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3874,6 +3874,10 @@ int i915_gpu_idle(struct drm_device *dev)
/* Flush everything onto the inactive list. */
for_each_engine(engine, dev_priv) {
+ ret = i915_scheduler_flush(engine, true);
+ if (ret < 0)
+ return ret;
+
if (!i915.enable_execlists) {
struct drm_i915_gem_request *req;
@@ -4612,6 +4616,7 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
struct drm_i915_gem_request *request, *target = NULL;
unsigned reset_counter;
int ret;
+ struct intel_engine_cs *engine;
ret = i915_gem_wait_for_error(&dev_priv->gpu_error);
if (ret)
@@ -4621,6 +4626,23 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
if (ret)
return ret;
+ for_each_engine(engine, dev_priv) {
+ /*
+ * Flush out scheduler entries that are getting 'stale'. Note
+ * that the following recent_enough test will only check
+ * against the time at which the request was submitted to the
+ * hardware (i.e. when it left the scheduler) not the time it
+ * was submitted to the driver.
+ *
+ * Also, there is not much point worring about busy return
+ * codes from the scheduler flush call. Even if more work
+ * cannot be submitted right now for whatever reason, we
+ * still want to throttle against stale work that has already
+ * been submitted.
+ */
+ i915_scheduler_flush_stamp(engine, recent_enough, false);
+ }
+
spin_lock(&file_priv->mm.lock);
list_for_each_entry(request, &file_priv->mm.request_list, client_list) {
if (time_after_eq(request->emitted_jiffies, recent_enough))
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index cf8b50a..580b9d2 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -342,6 +342,10 @@ static int i915_scheduler_pop_from_queue_locked(struct intel_engine_cs *engine,
* attempting to acquire a mutex while holding a spin lock is a Bad Idea.
* And releasing the one before acquiring the other leads to other code
* being run and interfering.
+ *
+ * Hence any caller that does not already have the mutex lock for other
+ * reasons should call i915_scheduler_submit_unlocked() instead in order to
+ * obtain the lock first.
*/
static int i915_scheduler_submit(struct intel_engine_cs *engine)
{
@@ -464,6 +468,22 @@ error:
return ret;
}
+static int i915_scheduler_submit_unlocked(struct intel_engine_cs *engine)
+{
+ struct drm_device *dev = engine->dev;
+ int ret;
+
+ ret = i915_mutex_lock_interruptible(dev);
+ if (ret)
+ return ret;
+
+ ret = i915_scheduler_submit(engine);
+
+ mutex_unlock(&dev->struct_mutex);
+
+ return ret;
+}
+
static void i915_generate_dependencies(struct i915_scheduler *scheduler,
struct i915_scheduler_queue_entry *node,
uint32_t engine)
@@ -909,6 +929,164 @@ void i915_scheduler_work_handler(struct work_struct *work)
i915_scheduler_process_work(engine);
}
+static int i915_scheduler_submit_max_priority(struct intel_engine_cs *engine,
+ bool is_locked)
+{
+ struct i915_scheduler_queue_entry *node;
+ struct drm_i915_private *dev_priv = to_i915(engine->dev);
+ struct i915_scheduler *scheduler = dev_priv->scheduler;
+ int ret, count = 0;
+ bool found;
+
+ do {
+ found = false;
+ spin_lock_irq(&scheduler->lock);
+ for_each_scheduler_node(node, engine->id) {
+ if (!I915_SQS_IS_QUEUED(node))
+ continue;
+
+ if (node->priority < scheduler->priority_level_max)
+ continue;
+
+ found = true;
+ break;
+ }
+ spin_unlock_irq(&scheduler->lock);
+
+ if (!found)
+ break;
+
+ if (is_locked)
+ ret = i915_scheduler_submit(engine);
+ else
+ ret = i915_scheduler_submit_unlocked(engine);
+ if (ret < 0)
+ return ret;
+
+ count += ret;
+ } while (found);
+
+ return count;
+}
+
+/**
+ * i915_scheduler_flush_stamp - force requests of a given age through the
+ * scheduler.
+ * @engine: Engine to be flushed
+ * @target: Jiffy based time stamp to flush up to
+ * @is_locked: Is the driver mutex lock held?
+ * DRM has a throttle by age of request facility. This requires waiting for
+ * outstanding work over a given age. This function helps that by forcing
+ * queued batch buffers over said age through the system.
+ * Returns zero on success or -EAGAIN if the scheduler is busy (e.g. waiting
+ * for a pre-emption event to complete) but the mutex lock is held which
+ * would prevent the scheduler's asynchronous processing from completing.
+ */
+int i915_scheduler_flush_stamp(struct intel_engine_cs *engine,
+ unsigned long target,
+ bool is_locked)
+{
+ struct i915_scheduler_queue_entry *node;
+ struct drm_i915_private *dev_priv;
+ struct i915_scheduler *scheduler;
+ int flush_count = 0;
+
+ if (!engine)
+ return -EINVAL;
+
+ dev_priv = to_i915(engine->dev);
+ scheduler = dev_priv->scheduler;
+
+ if (!scheduler)
+ return 0;
+
+ if (is_locked && (scheduler->flags[engine->id] & I915_SF_SUBMITTING)) {
+ /*
+ * Scheduler is busy already submitting another batch,
+ * come back later rather than going recursive...
+ */
+ return -EAGAIN;
+ }
+
+ spin_lock_irq(&scheduler->lock);
+ i915_scheduler_priority_bump_clear(scheduler);
+ for_each_scheduler_node(node, engine->id) {
+ if (!I915_SQS_IS_QUEUED(node))
+ continue;
+
+ if (node->stamp > target)
+ continue;
+
+ flush_count = i915_scheduler_priority_bump(scheduler,
+ node, scheduler->priority_level_max);
+ }
+ spin_unlock_irq(&scheduler->lock);
+
+ if (flush_count) {
+ DRM_DEBUG_DRIVER("<%s> Bumped %d entries\n", engine->name, flush_count);
+ flush_count = i915_scheduler_submit_max_priority(engine, is_locked);
+ }
+
+ return flush_count;
+}
+
+/**
+ * i915_scheduler_flush - force all requests through the scheduler.
+ * @engine: Engine to be flushed
+ * @is_locked: Is the driver mutex lock held?
+ * For various reasons it is sometimes necessary to the scheduler out, e.g.
+ * due to engine reset.
+ * Returns zero on success or -EAGAIN if the scheduler is busy (e.g. waiting
+ * for a pre-emption event to complete) but the mutex lock is held which
+ * would prevent the scheduler's asynchronous processing from completing.
+ */
+int i915_scheduler_flush(struct intel_engine_cs *engine, bool is_locked)
+{
+ struct i915_scheduler_queue_entry *node;
+ struct drm_i915_private *dev_priv;
+ struct i915_scheduler *scheduler;
+ bool found;
+ int ret;
+ uint32_t count = 0;
+
+ if (!engine)
+ return -EINVAL;
+
+ dev_priv = to_i915(engine->dev);
+ scheduler = dev_priv->scheduler;
+
+ if (!scheduler)
+ return 0;
+
+ WARN_ON(is_locked && (scheduler->flags[engine->id] & I915_SF_SUBMITTING));
+
+ do {
+ found = false;
+ spin_lock_irq(&scheduler->lock);
+ for_each_scheduler_node(node, engine->id) {
+ if (!I915_SQS_IS_QUEUED(node))
+ continue;
+
+ found = true;
+ break;
+ }
+ spin_unlock_irq(&scheduler->lock);
+
+ if (found) {
+ if (is_locked)
+ ret = i915_scheduler_submit(engine);
+ else
+ ret = i915_scheduler_submit_unlocked(engine);
+ if (ret < 0)
+ return ret;
+
+ count += ret;
+ }
+ } while (found);
+
+ return count;
+}
+
/**
* i915_scheduler_is_mutex_required - query if it is safe to hold the mutex
* lock while waiting for the given request.
diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h
index 38e860d..92dd5df 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.h
+++ b/drivers/gpu/drm/i915/i915_scheduler.h
@@ -111,6 +111,9 @@ int i915_scheduler_queue_execbuffer(struct i915_scheduler_queue_entry *qe);
bool i915_scheduler_notify_request(struct drm_i915_gem_request *req);
void i915_scheduler_wakeup(struct drm_device *dev);
void i915_scheduler_work_handler(struct work_struct *work);
+int i915_scheduler_flush(struct intel_engine_cs *engine, bool is_locked);
+int i915_scheduler_flush_stamp(struct intel_engine_cs *engine,
+ unsigned long stamp, bool is_locked);
bool i915_scheduler_is_mutex_required(struct drm_i915_gem_request *req);
#endif /* _I915_SCHEDULER_H_ */
--
1.9.1
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