With the disappearance of NEWCLIENT, we no longer need to provide the
priority boost on preemption in order to prevent repeated gazumping,
and we can remove the dead code.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_lrc.c | 59 +++++------------------------
1 file changed, 10 insertions(+), 49 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index b5e82171df8f..f263a8374273 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -164,8 +164,6 @@
#define WA_TAIL_DWORDS 2
#define WA_TAIL_BYTES (sizeof(u32) * WA_TAIL_DWORDS)
-#define ACTIVE_PRIORITY (I915_PRIORITY_NOSEMAPHORE)
-
static int execlists_context_deferred_alloc(struct intel_context *ce,
struct intel_engine_cs *engine);
static void execlists_init_reg_state(u32 *reg_state,
@@ -189,23 +187,12 @@ static int effective_prio(const struct i915_request *rq)
/*
* On unwinding the active request, we give it a priority bump
- * equivalent to a freshly submitted request. This protects it from
- * being gazumped again, but it would be preferable if we didn't
- * let it be gazumped in the first place!
- *
- * See __unwind_incomplete_requests()
+ * if it has completed waiting on any semaphore. If we know that
+ * the request has already started, we can prevent an unwanted
+ * preempt-to-idle cycle by taking that into account now.
*/
- if (~prio & ACTIVE_PRIORITY && __i915_request_has_started(rq)) {
- /*
- * After preemption, we insert the active request at the
- * end of the new priority level. This means that we will be
- * _lower_ priority than the preemptee all things equal (and
- * so the preemption is valid), so adjust our comparison
- * accordingly.
- */
- prio |= ACTIVE_PRIORITY;
- prio--;
- }
+ if (__i915_request_has_started(rq))
+ prio |= I915_PRIORITY_NOSEMAPHORE;
/* Restrict mere WAIT boosts from triggering preemption */
return prio | __NO_PREEMPTION;
@@ -371,11 +358,11 @@ static void unwind_wa_tail(struct i915_request *rq)
}
static struct i915_request *
-__unwind_incomplete_requests(struct intel_engine_cs *engine, int boost)
+__unwind_incomplete_requests(struct intel_engine_cs *engine)
{
struct i915_request *rq, *rn, *active = NULL;
struct list_head *uninitialized_var(pl);
- int prio = I915_PRIORITY_INVALID | boost;
+ int prio = I915_PRIORITY_INVALID;
lockdep_assert_held(&engine->timeline.lock);
@@ -402,31 +389,6 @@ __unwind_incomplete_requests(struct intel_engine_cs *engine, int boost)
active = rq;
}
- /*
- * The active request is now effectively the start of a new client
- * stream, so give it the equivalent small priority bump to prevent
- * it being gazumped a second time by another peer.
- *
- * Note we have to be careful not to apply a priority boost to a request
- * still spinning on its semaphores. If the request hasn't started, that
- * means it is still waiting for its dependencies to be signaled, and
- * if we apply a priority boost to this request, we will boost it past
- * its signalers and so break PI.
- *
- * One consequence of this preemption boost is that we may jump
- * over lesser priorities (such as I915_PRIORITY_WAIT), effectively
- * making those priorities non-preemptible. They will be moved forward
- * in the priority queue, but they will not gain immediate access to
- * the GPU.
- */
- if (~prio & boost && __i915_request_has_started(active)) {
- prio |= boost;
- GEM_BUG_ON(active->sched.attr.priority >= prio);
- active->sched.attr.priority = prio;
- list_move_tail(&active->sched.link,
- i915_sched_lookup_priolist(engine, prio));
- }
-
return active;
}
@@ -436,7 +398,7 @@ execlists_unwind_incomplete_requests(struct intel_engine_execlists *execlists)
struct intel_engine_cs *engine =
container_of(execlists, typeof(*engine), execlists);
- return __unwind_incomplete_requests(engine, 0);
+ return __unwind_incomplete_requests(engine);
}
static inline void
@@ -657,8 +619,7 @@ static void complete_preempt_context(struct intel_engine_execlists *execlists)
execlists_cancel_port_requests(execlists);
__unwind_incomplete_requests(container_of(execlists,
struct intel_engine_cs,
- execlists),
- ACTIVE_PRIORITY);
+ execlists));
}
static void execlists_dequeue(struct intel_engine_cs *engine)
@@ -1911,7 +1872,7 @@ static void __execlists_reset(struct intel_engine_cs *engine, bool stalled)
execlists_cancel_port_requests(execlists);
/* Push back any incomplete requests for replay after the reset. */
- rq = __unwind_incomplete_requests(engine, 0);
+ rq = __unwind_incomplete_requests(engine);
if (!rq)
goto out_replay;
--
2.20.1
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