[PATCH 01/14] drm/i915/hangcheck: Track context changes

Chris Wilson
2019-05-01T11:45:56Z

Given sufficient preemption, we may see a busy system that doesn't
advance seqno while performing work across multiple contexts, and given
sufficient pathology not even notice a change in ACTHD. What does change
between the preempting contexts is their RING, so take note of that and
treat a change in the ring address as being an indication of forward
progress.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
---
drivers/gpu/drm/i915/gt/intel_engine_types.h | 1 +
drivers/gpu/drm/i915/gt/intel_hangcheck.c | 12 +++++++++---
2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
index 9d64e33f8427..c0ab11b12e14 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
@@ -53,6 +53,7 @@ struct intel_instdone {

struct intel_engine_hangcheck {
u64 acthd;
+ u32 last_ring;
u32 last_seqno;
u32 next_seqno;
unsigned long action_timestamp;
diff --git a/drivers/gpu/drm/i915/gt/intel_hangcheck.c b/drivers/gpu/drm/i915/gt/intel_hangcheck.c
index e5eaa06fe74d..721ab74a382f 100644
--- a/drivers/gpu/drm/i915/gt/intel_hangcheck.c
+++ b/drivers/gpu/drm/i915/gt/intel_hangcheck.c
@@ -27,6 +27,7 @@

struct hangcheck {
u64 acthd;
+ u32 ring;
u32 seqno;
enum intel_engine_hangcheck_action action;
unsigned long action_timestamp;
@@ -134,6 +135,7 @@ static void hangcheck_load_sample(struct intel_engine_cs *engine,
{
hc->acthd = intel_engine_get_active_head(engine);
hc->seqno = intel_engine_get_hangcheck_seqno(engine);
+ hc->ring = ENGINE_READ(engine, RING_START);
}

static void hangcheck_store_sample(struct intel_engine_cs *engine,
@@ -141,18 +143,22 @@ static void hangcheck_store_sample(struct intel_engine_cs *engine,
{
engine->hangcheck.acthd = hc->acthd;
engine->hangcheck.last_seqno = hc->seqno;
+ engine->hangcheck.last_ring = hc->ring;
}

static enum intel_engine_hangcheck_action
hangcheck_get_action(struct intel_engine_cs *engine,
const struct hangcheck *hc)
{
- if (engine->hangcheck.last_seqno != hc->seqno)
- return ENGINE_ACTIVE_SEQNO;
-
if (intel_engine_is_idle(engine))
return ENGINE_IDLE;

+ if (engine->hangcheck.last_ring != hc->ring)
+ return ENGINE_ACTIVE_SEQNO;
+
+ if (engine->hangcheck.last_seqno != hc->seqno)
+ return ENGINE_ACTIVE_SEQNO;
+
return engine_stuck(engine, hc->acthd);
}

--
2.20.1