Re: [Intel-gfx] [PATCH v3] drm/i915/gt: Track the most recent pulse for the heartbeat

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> Since we track the idle_pulse for flushing the barriers and avoid
> re-emitting the pulse upon idling if no futher action is required, this
> also impacts the heartbeat. Before emitting a fresh heartbeat, we look
> at the engine idle status and assume that if the pulse was the last
> request emitted along the heartbeat, the engine is idling and a
> heartbeat pulse not required. This assumption fails, but we can reuse
> the idle pulse as the heartbeat if we are yet to emit one, and so track
> the status of that pulse for our engine health check.
>
> This impacts tgl/rcs0 as we rely on the heartbeat for our healthcheck for
> the normal preemption detection mechanism is disabled by default.
>
> Testcase: igt/gem_exec_schedule/preempt-hang/rcs0 #tgl
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c | 6 +++---
>  1 file changed, 3 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 5067d0524d4b..9060385cd69e 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
> @@ -41,6 +41,8 @@ static void idle_pulse(struct intel_engine_cs *engine, struct i915_request *rq)
>  {
>  	engine->wakeref_serial = READ_ONCE(engine->serial) + 1;
>  	i915_request_add_active_barriers(rq);
> +	if (!engine->heartbeat.systole && intel_engine_has_heartbeat(engine))
> +		engine->heartbeat.systole = i915_request_get(rq);
>  }
>  
>  static void show_heartbeat(const struct i915_request *rq,
> @@ -144,8 +146,6 @@ static void heartbeat(struct work_struct *wrk)
>  		goto unlock;
>  
>  	idle_pulse(engine, rq);
> -	if (engine->i915->params.enable_hangcheck)
> -		engine->heartbeat.systole = i915_request_get(rq);
>  
>  	__i915_request_commit(rq);
>  	__i915_request_queue(rq, &attr);
> @@ -153,7 +153,7 @@ static void heartbeat(struct work_struct *wrk)
>  unlock:
>  	mutex_unlock(&ce->timeline->mutex);
>  out:
> -	if (!next_heartbeat(engine))
> +	if (!engine->i915->params.enable_hangcheck || !next_heartbeat(engine))
>  		i915_request_put(fetch_and_zero(&engine->heartbeat.systole));
>  	intel_engine_pm_put(engine);
>  }
> -- 
> 2.20.1
>
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