On 19/05/16 12:32, Chris Wilson wrote:
We can forgo queuing the hangcheck from the start of every request to
until we wait upon a request. This reduces the overhead of every
request, but may increase the latency of detecting a hang. Howeever, if
nothing every waits upon a hang, did it ever hang? It also improves the
Maybe it is better to detect and reset sooner rather than later in case
the hang is burning power and may now only get looked at at some random
time in the future? It is probably quite weak argument but it came to mind.
robustness of the wait-request by ensuring that the hangchecker is
indeed running before we sleep indefinitely (and thereby ensuring that
we never actually sleep forever waiting for a dead GPU).
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem.c | 9 +++++----
drivers/gpu/drm/i915/i915_irq.c | 10 ++++------
2 files changed, 9 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 24cab8802c2e..06013b9fbc6a 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1310,6 +1310,9 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
break;
}
+ /* Ensure that even if the GPU hangs, we get woken up. */
+ i915_queue_hangcheck(dev_priv);
+
timer.function = NULL;
if (timeout || missed_irq(dev_priv, engine)) {
unsigned long expire;
@@ -2654,8 +2657,6 @@ void __i915_add_request(struct drm_i915_gem_request *request,
/* Not allowed to fail! */
WARN(ret, "emit|add_request failed: %d!\n", ret);
- i915_queue_hangcheck(engine->i915);
-
queue_delayed_work(dev_priv->wq,
&dev_priv->mm.retire_work,
round_jiffies_up_relative(HZ));
@@ -2999,8 +3000,8 @@ i915_gem_retire_requests(struct drm_i915_private *dev_priv)
if (idle)
mod_delayed_work(dev_priv->wq,
- &dev_priv->mm.idle_work,
- msecs_to_jiffies(100));
+ &dev_priv->mm.idle_work,
+ msecs_to_jiffies(100));
return idle;
}
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index f0d941455bed..4818fcb5e960 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -3148,10 +3148,10 @@ static void i915_hangcheck_elapsed(struct work_struct *work)
intel_uncore_arm_unclaimed_mmio_detection(dev_priv);
for_each_engine_id(engine, dev_priv, id) {
+ bool busy = waitqueue_active(&engine->irq_queue);
u64 acthd;
u32 seqno;
unsigned user_interrupts;
- bool busy = true;
semaphore_clear_deadlocks(dev_priv);
@@ -3174,12 +3174,11 @@ static void i915_hangcheck_elapsed(struct work_struct *work)
if (engine->hangcheck.seqno == seqno) {
if (ring_idle(engine, seqno)) {
engine->hangcheck.action = HANGCHECK_IDLE;
- if (waitqueue_active(&engine->irq_queue)) {
+ if (busy) {
/* Safeguard against driver failure */
user_interrupts = kick_waiters(engine);
engine->hangcheck.score += BUSY;
- } else
- busy = false;
+ }
} else {
/* We always increment the hangcheck score
* if the ring is busy and still processing
@@ -3253,9 +3252,8 @@ static void i915_hangcheck_elapsed(struct work_struct *work)
goto out;
}
+ /* Reset timer in case GPU hangs without another request being added */
if (busy_count)
- /* Reset timer case chip hangs without another request
- * being added */
i915_queue_hangcheck(dev_priv);
out:
With a disclaimer that I don't really know hangcheck - it looks that
previously it was getting re-queued all the time until the engine when
idle, regardless of if there were waiters. With this change it looks
like that is gone. If there are no waiters it won't get re-queued. How
does incrementing the hangcheck score work now?
Regards,
Tvrtko
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