We don't want to busywait on the GPU if we have other work to do. If we
give non-busywaiting workloads higher (initial) priority than workloads
that require a busywait, we will prioritise work that is ready to run
immediately.
Testcase: igt/gem_exec_schedule/semaphore
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_request.c | 8 +++++++-
drivers/gpu/drm/i915/i915_scheduler.c | 2 +-
drivers/gpu/drm/i915/i915_scheduler.h | 11 +++++++----
drivers/gpu/drm/i915/intel_lrc.c | 5 +++--
4 files changed, 18 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 6d825cd28ae6..30cd8724d39f 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -844,7 +844,7 @@ emit_semaphore_wait(struct i915_request *to,
intel_ring_advance(to, cs);
}
- to->sched.semaphore = true;
+ to->sched.semaphore |= I915_SCHED_HAS_SEMAPHORE;
return 0;
}
@@ -867,6 +867,9 @@ i915_request_await_request(struct i915_request *to, struct i915_request *from)
return ret;
}
+ if (from->sched.semaphore && !i915_request_started(from))
+ to->sched.semaphore |= I915_SCHED_CHAIN_SEMAPHORE;
+
if (to->engine == from->engine) {
ret = i915_sw_fence_await_sw_fence_gfp(&to->submit,
&from->submit,
@@ -1117,6 +1120,9 @@ void i915_request_add(struct i915_request *request)
if (engine->schedule) {
struct i915_sched_attr attr = request->gem_context->sched;
+ if (!request->sched.semaphore)
+ attr.priority |= I915_PRIORITY_NOSEMAPHORE;
+
/*
* Boost priorities to new clients (new request flows).
*
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index 7f9c4018530b..702204d4e729 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -29,7 +29,7 @@ void i915_sched_node_init(struct i915_sched_node *node)
INIT_LIST_HEAD(&node->waiters_list);
INIT_LIST_HEAD(&node->link);
node->attr.priority = I915_PRIORITY_INVALID;
- node->semaphore = false;
+ node->semaphore = 0;
}
static struct i915_dependency *
diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h
index d764cf10536f..d84f09e8c248 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.h
+++ b/drivers/gpu/drm/i915/i915_scheduler.h
@@ -24,14 +24,15 @@ enum {
I915_PRIORITY_INVALID = INT_MIN
};
-#define I915_USER_PRIORITY_SHIFT 2
+#define I915_USER_PRIORITY_SHIFT 3
#define I915_USER_PRIORITY(x) ((x) << I915_USER_PRIORITY_SHIFT)
#define I915_PRIORITY_COUNT BIT(I915_USER_PRIORITY_SHIFT)
#define I915_PRIORITY_MASK (I915_PRIORITY_COUNT - 1)
-#define I915_PRIORITY_WAIT ((u8)BIT(0))
-#define I915_PRIORITY_NEWCLIENT ((u8)BIT(1))
+#define I915_PRIORITY_WAIT ((u8)BIT(0))
+#define I915_PRIORITY_NEWCLIENT ((u8)BIT(1))
+#define I915_PRIORITY_NOSEMAPHORE ((u8)BIT(2))
struct i915_sched_attr {
/**
@@ -72,7 +73,9 @@ struct i915_sched_node {
struct list_head waiters_list; /* those after us, they depend upon us */
struct list_head link;
struct i915_sched_attr attr;
- bool semaphore;
+ unsigned long semaphore;
+#define I915_SCHED_HAS_SEMAPHORE BIT(0)
+#define I915_SCHED_CHAIN_SEMAPHORE BIT(1)
};
struct i915_dependency {
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index f7f16b8d3422..4fcee493dddb 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -164,7 +164,7 @@
#define WA_TAIL_DWORDS 2
#define WA_TAIL_BYTES (sizeof(u32) * WA_TAIL_DWORDS)
-#define ACTIVE_PRIORITY (I915_PRIORITY_NEWCLIENT)
+#define ACTIVE_PRIORITY (I915_PRIORITY_NEWCLIENT | I915_PRIORITY_NOSEMAPHORE)
static int execlists_context_deferred_alloc(struct i915_gem_context *ctx,
struct intel_engine_cs *engine,
@@ -608,7 +608,8 @@ static bool can_merge_rq(const struct i915_request *prev,
* rules should mean that if this semaphore is preempted, its
* dependency chain is preserved and suitably promoted via PI.
*/
- if (prev->sched.semaphore && !i915_request_started(prev))
+ if (prev->sched.semaphore & I915_SCHED_HAS_SEMAPHORE &&
+ !i915_request_started(prev))
return false;
if (!can_merge_ctx(prev->hw_context, next->hw_context))
--
2.20.1
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