Re: [PATCH 27/34] drm/i915: Remove the intel_engine_notify tracepoint

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 21/01/2019 22:21, Chris Wilson wrote:
> The global seqno is defunct and so we have no meaningful indicator of
> forward progress for an engine. You need to listen to the request
> signaling tracepoints instead.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_irq.c   |  2 --
>   drivers/gpu/drm/i915/i915_trace.h | 25 -------------------------
>   2 files changed, 27 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 5fd5080c4ccb..71d11dc2c235 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1209,8 +1209,6 @@ static void notify_ring(struct intel_engine_cs *engine)
>   		wake_up_process(tsk);
>   
>   	rcu_read_unlock();
> -
> -	trace_intel_engine_notify(engine, wait);
>   }
>   
>   static void vlv_c0_read(struct drm_i915_private *dev_priv,
> diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
> index 33d90eca9cdd..cb5bc65d575d 100644
> --- a/drivers/gpu/drm/i915/i915_trace.h
> +++ b/drivers/gpu/drm/i915/i915_trace.h
> @@ -750,31 +750,6 @@ trace_i915_request_out(struct i915_request *rq)
>   #endif
>   #endif
>   
> -TRACE_EVENT(intel_engine_notify,
> -	    TP_PROTO(struct intel_engine_cs *engine, bool waiters),
> -	    TP_ARGS(engine, waiters),
> -
> -	    TP_STRUCT__entry(
> -			     __field(u32, dev)
> -			     __field(u16, class)
> -			     __field(u16, instance)
> -			     __field(u32, seqno)
> -			     __field(bool, waiters)
> -			     ),
> -
> -	    TP_fast_assign(
> -			   __entry->dev = engine->i915->drm.primary->index;
> -			   __entry->class = engine->uabi_class;
> -			   __entry->instance = engine->instance;
> -			   __entry->seqno = intel_engine_get_seqno(engine);
> -			   __entry->waiters = waiters;
> -			   ),
> -
> -	    TP_printk("dev=%u, engine=%u:%u, seqno=%u, waiters=%u",
> -		      __entry->dev, __entry->class, __entry->instance,
> -		      __entry->seqno, __entry->waiters)
> -);
> -
>   DEFINE_EVENT(i915_request, i915_request_retire,
>   	    TP_PROTO(struct i915_request *rq),
>   	    TP_ARGS(rq)
> 

I cannot decide if keeping what we can would make it useful. Certainly 
not for debugging intel_engine_breadcrumbs_irq.. a sequence of 
intel_engine_notify(dev, class, instance) -> dma_fence_signaled would be 
a very unreliable trace of what engine actually executed something. What 
do you think?

Regards,

Tvrtko



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