On 17/02/2017 10:58, Chris Wilson wrote:
On Fri, Feb 17, 2017 at 10:48:50AM +0000, Tvrtko Ursulin wrote:
On 17/02/2017 10:18, Chris Wilson wrote:
If the waiter was currently running, assume it hasn't had a chance
to process the pending interupt (e.g, low priority task on a loaded
system) and wait until it sleeps before declaring a missed interrupt.
References: https://bugs.freedesktop.org/show_bug.cgi?id=99816
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_breadcrumbs.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
index 4395b177493e..2ad29fb77b2d 100644
--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
@@ -45,6 +45,15 @@ static void intel_breadcrumbs_hangcheck(unsigned long data)
return;
}
+ /* If the waiter was currently running, assume it hasn't had a chance
+ * to process the pending interupt (e.g, low priority task on a loaded
+ * system) and wait until it sleeps before declaring a missed interrupt.
+ */
+ if (!intel_engine_wakeup(engine)) {
+ mod_timer(&b->hangcheck, wait_timeout());
+ return;
+ }
+
DRM_DEBUG("Hangcheck timer elapsed... %s idle\n", engine->name);
set_bit(engine->id, &engine->i915->gpu_error.missed_irq_rings);
mod_timer(&engine->breadcrumbs.fake_irq, jiffies + 1);
Change here is that we would never declare a GPU hang is userspace
would just wait indefinitely, or in other words with this patch we
would rely on userspace timing out on their waits in order to
declare a hang.
Surely you mean the other way around? The only way we get to now declare a
missed-interrupt and then queue a hangcheck here is if userspace sleeps.
Hm, in fact even with the current code, if the userspace keeps
exiting and re-entering the wait we would be re-arming the hangcheck
timer and so also never notice a GPU hang.
Correct. It is not the only way we arm the GPU hangcheck.
gem_busy/hang, gem_wait/busy-hang check that we do detect hangs even if
userspace never sleeps.
Looks good after some more digging through the code and a brief IRC
discussion. We only fall back to rapid wakeups (fake_irq) if there are
waiters now, which is inline with the rest of the code.
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Regards,
Tvrtko
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