On 18/09/2017 17:27, Chris Wilson wrote:
As we now check if the seqno is complete in order to signal the fence,
we can also decide not to wake up the first_waiter until it is ready
(since it is waiting on the same seqno). The only caveat is that if we
need the engine->irq_seqno_barrier to enforce some coherency between an
interrupt and the seqno read, we have to always wake the waiter in order
to perform that heavyweight barrier.
Signed-off-by: Chris Wilson <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
---
drivers/gpu/drm/i915/i915_irq.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 4d0e8f76ed1a..bb69c5b0efc4 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1038,6 +1038,8 @@ static void notify_ring(struct intel_engine_cs *engine)
spin_lock(&engine->breadcrumbs.irq_lock);
wait = engine->breadcrumbs.irq_wait;
if (wait) {
+ bool wakeup = engine->irq_seqno_barrier;
+
/* We use a callback from the dma-fence to submit
* requests after waiting on our own requests. To
* ensure minimum delay in queuing the next request to
@@ -1050,12 +1052,15 @@ static void notify_ring(struct intel_engine_cs *engine)
* and many waiters.
*/
if (i915_seqno_passed(intel_engine_get_seqno(engine),
- wait->seqno) &&
- !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
- &wait->request->fence.flags))
- rq = i915_gem_request_get(wait->request);
+ wait->seqno)) {
+ wakeup = true;
+ if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
+ &wait->request->fence.flags))
+ rq = i915_gem_request_get(wait->request);
+ }
- wake_up_process(wait->tsk);
+ if (wakeup)
+ wake_up_process(wait->tsk);
} else {
__intel_engine_disarm_breadcrumbs(engine);
}
Looks straightforward enough.
Reviewed-by: Tvrtko Ursulin <[email protected]>
Regards,
Tvrtko
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