From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Sun, 6 May 2018 18:13:28 +0100
Subject: drm/i915: Speed up idle detection by kicking the tasklets
Git-commit: dd0cf235d81f24c1ba80c4a000bafc9f2dce3840
Patch-mainline: v4.19-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166
We rely on ksoftirqd to run in a timely fashion in order to drain the
execlists queue. Quite frequently, it does not. In some cases we may see
latencies of over 200ms triggering our idle timeouts and forcing us to
declare the driver wedged!
Thus we can speed up idle detection by bypassing ksoftirqd in these
cases and flush our tasklet to confirm if we are indeed still waiting
for the ELSP to drain.
v2: Put the execlists.first check back; it is required for handling
reset!
References: https://bugs.freedesktop.org/show_bug.cgi?id=106373
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180506171328.30034-1-chris@chris-wilson.co.uk
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
drivers/gpu/drm/i915/intel_engine_cs.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -973,10 +973,19 @@ bool intel_engine_is_idle(struct intel_e
return true;
/* Waiting to drain ELSP? */
- if (READ_ONCE(engine->execlists.active))
- return false;
+ if (READ_ONCE(engine->execlists.active)) {
+ struct intel_engine_execlists *execlists = &engine->execlists;
+
+ if (tasklet_trylock(&execlists->tasklet)) {
+ execlists->tasklet.func(execlists->tasklet.data);
+ tasklet_unlock(&execlists->tasklet);
+ }
+
+ if (READ_ONCE(execlists->active))
+ return false;
+ }
- /* ELSP is empty, but there are ready requests? */
+ /* ELSP is empty, but there are ready requests? E.g. after reset */
if (READ_ONCE(engine->execlists.first))
return false;