On 16/07/2020 18:28, Chris Wilson wrote:
After staring at the breadcrumb enabling/cancellation and coming to the
conclusion that the cause of the mysterious stale breadcrumbs must the
act of submitting a completed requests, we can then redirect those
completed requests onto a dedicated signaled_list at the time of
construction and so eliminate intel_engine_transfer_stale_breadcrumbs().
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 44 +++++++--------------
drivers/gpu/drm/i915/gt/intel_engine.h | 3 --
drivers/gpu/drm/i915/gt/intel_lrc.c | 15 -------
drivers/gpu/drm/i915/i915_request.c | 5 +--
4 files changed, 17 insertions(+), 50 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
index a0f52417238c..11660bef1545 100644
--- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
@@ -144,7 +144,6 @@ static void add_retire(struct intel_breadcrumbs *b, struct intel_timeline *tl)
static void __signal_request(struct i915_request *rq, struct list_head *signals)
{
- GEM_BUG_ON(!test_bit(I915_FENCE_FLAG_SIGNAL, &rq->fence.flags));
clear_bit(I915_FENCE_FLAG_SIGNAL, &rq->fence.flags);
if (!__dma_fence_signal(&rq->fence))
@@ -278,32 +277,6 @@ void intel_engine_reset_breadcrumbs(struct intel_engine_cs *engine)
spin_unlock_irqrestore(&b->irq_lock, flags);
}
-void intel_engine_transfer_stale_breadcrumbs(struct intel_engine_cs *engine,
- struct intel_context *ce)
-{
- struct intel_breadcrumbs *b = &engine->breadcrumbs;
- unsigned long flags;
-
- spin_lock_irqsave(&b->irq_lock, flags);
- if (!list_empty(&ce->signals)) {
- struct i915_request *rq, *next;
-
- /* Queue for executing the signal callbacks in the irq_work */
- list_for_each_entry_safe(rq, next, &ce->signals, signal_link) {
- GEM_BUG_ON(rq->engine != engine);
- GEM_BUG_ON(!__request_completed(rq));
-
- __signal_request(rq, &b->signaled_requests);
- }
-
- INIT_LIST_HEAD(&ce->signals);
- list_del_init(&ce->signal_link);
-
- irq_work_queue(&b->irq_work);
- }
- spin_unlock_irqrestore(&b->irq_lock, flags);
-}
-
void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine)
{
}
@@ -317,6 +290,17 @@ static void insert_breadcrumb(struct i915_request *rq,
if (test_bit(I915_FENCE_FLAG_SIGNAL, &rq->fence.flags))
return;
+ /*
+ * If the request is already completed, we can transfer it
+ * straight onto a signaled list, and queue the irq worker for
+ * its signal completion.
+ */
+ if (__request_completed(rq)) {
+ __signal_request(rq, &b->signaled_requests);
+ irq_work_queue(&b->irq_work);
+ return;
+ }
+
__intel_breadcrumbs_arm_irq(b);
/*
@@ -341,8 +325,10 @@ static void insert_breadcrumb(struct i915_request *rq,
break;
}
list_add(&rq->signal_link, pos);
- if (pos == &ce->signals) /* catch transitions from empty list */
+ if (pos == &ce->signals) { /* catch transitions from empty list */
list_move_tail(&ce->signal_link, &b->signalers);
+ irq_work_queue(&b->irq_work); /* check after enabling irq */
+ }
GEM_BUG_ON(!check_signal_order(ce, rq));
set_bit(I915_FENCE_FLAG_SIGNAL, &rq->fence.flags);
@@ -401,7 +387,7 @@ bool i915_request_enable_breadcrumb(struct i915_request *rq)
spin_unlock(&b->irq_lock);
- return !__request_completed(rq);
+ return true;
Maybe my in head diff apply is failing me, but I think there isn't a
"return false" path left so could be made a return void function.
Regards,
Tvrtko
}
void i915_request_cancel_breadcrumb(struct i915_request *rq)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine.h b/drivers/gpu/drm/i915/gt/intel_engine.h
index a9249a23903a..faf00a353e25 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine.h
@@ -237,9 +237,6 @@ intel_engine_signal_breadcrumbs(struct intel_engine_cs *engine)
void intel_engine_reset_breadcrumbs(struct intel_engine_cs *engine);
void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine);
-void intel_engine_transfer_stale_breadcrumbs(struct intel_engine_cs *engine,
- struct intel_context *ce);
-
void intel_engine_print_breadcrumbs(struct intel_engine_cs *engine,
struct drm_printer *p);
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 21c16e31c4fe..88a5c155154d 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -1805,18 +1805,6 @@ static bool virtual_matches(const struct virtual_engine *ve,
return true;
}
-static void virtual_xfer_breadcrumbs(struct virtual_engine *ve)
-{
- /*
- * All the outstanding signals on ve->siblings[0] must have
- * been completed, just pending the interrupt handler. As those
- * signals still refer to the old sibling (via rq->engine), we must
- * transfer those to the old irq_worker to keep our locking
- * consistent.
- */
- intel_engine_transfer_stale_breadcrumbs(ve->siblings[0], &ve->context);
-}
-
#define for_each_waiter(p__, rq__) \
list_for_each_entry_lockless(p__, \
&(rq__)->sched.waiters_list, \
@@ -2275,9 +2263,6 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
virtual_update_register_offsets(regs,
engine);
- if (!list_empty(&ve->context.signals))
- virtual_xfer_breadcrumbs(ve);
-
/*
* Move the bound engine to the top of the list
* for future execution. We then kick this
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index fc25382e1201..d88f046ccbdd 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -609,9 +609,8 @@ bool __i915_request_submit(struct i915_request *request)
*/
__notify_execute_cb_irq(request);
- if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &request->fence.flags) &&
- !i915_request_enable_breadcrumb(request))
- intel_engine_signal_breadcrumbs(engine);
+ if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &request->fence.flags))
+ i915_request_enable_breadcrumb(request);
return result;
}
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