Chris Wilson <ch...@chris-wilson.co.uk> writes:
> If the ring submission is stalled on an external request, nothing can be
> submitted, not even the heartbeat in the kernel context. Since nothing
> is running, resetting the engine/device does not unblock the system and
> is pointless. We can see if the heartbeat is supposed to be running
> before declaring foul.
>
> Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
> ---
> .../gpu/drm/i915/gt/intel_engine_heartbeat.c | 19 ++++++++++++++++---
> 1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
> b/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
> index 5136c8bf112d..f67ad937eefb 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
> @@ -48,8 +48,10 @@ static void show_heartbeat(const struct i915_request *rq,
> struct drm_printer p = drm_debug_printer("heartbeat");
>
> intel_engine_dump(engine, &p,
> - "%s heartbeat {prio:%d} not ticking\n",
> + "%s heartbeat {seqno:%llx:%lld, prio:%d} not
> ticking\n",
> engine->name,
> + rq->fence.context,
> + rq->fence.seqno,
> rq->sched.attr.priority);
> }
>
> @@ -76,8 +78,19 @@ static void heartbeat(struct work_struct *wrk)
> goto out;
>
> if (engine->heartbeat.systole) {
> - if (engine->schedule &&
> - rq->sched.attr.priority < I915_PRIORITY_BARRIER) {
> + if (!i915_sw_fence_signaled(&rq->submit)) {
> + /*
> + * Not yet submitted, system is stalled.
> + *
> + * This more often happens for ring submission,
> + * where all contexts are funnelled into a common
> + * ringbuffer. If one context is blocked on an
> + * external fence, not only is it not submitted,
> + * but all other contexts, including the kernel
> + * context are stuck waiting for the signal.
> + */
The solution how to save the system evades me.
But piling the heartbeat on top does not help with it in
any case.
Reviewed-by: Mika Kuoppala <mika.kuopp...@linux.intel.com>
> + } else if (engine->schedule &&
> + rq->sched.attr.priority < I915_PRIORITY_BARRIER) {
> /*
> * Gradually raise the priority of the heartbeat to
> * give high priority work [which presumably desires
> --
> 2.20.1
>
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