[Intel-gfx] [PATCH 09/13] drm/i915: Add a tracepoint for using a semaphore

[Ville Syrjälä]

On Mon, Sep 23, 2013 at 05:33:26PM -0300, Rodrigo Vivi wrote:
> From: Chris Wilson <chris at chris-wilson.co.uk>
> 
> So that we can find the callers who introduce a ring stall. A single
> ring stall is not too unwelcome, the right issue becomes when they start
> to interlock and prevent any concurrent work. That, however, is a little
> tricker to detect with a mere tracepoint!
> 
> v2: Rebrand it as a ring event, rather than an object event.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at gmail.com>

Just wondering if we would want to see the seqno(s) in the trace as well?

But anyway, the patch looks fine.
Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

> ---
>  drivers/gpu/drm/i915/i915_gem.c   |  2 ++
>  drivers/gpu/drm/i915/i915_trace.h | 19 +++++++++++++++++++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index d68cc5c..4a16491 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2614,6 +2614,8 @@ i915_gem_object_sync(struct drm_i915_gem_object *obj,
>  	if (ret)
>  		return ret;
>  
> +	trace_i915_gem_ring_sync_to(from, to);
> +
>  	ret = to->sync_to(to, from, seqno);
>  	if (!ret)
>  		/* We use last_read_seqno because sync_to()
> diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
> index 5c8e36a..48e8f07 100644
> --- a/drivers/gpu/drm/i915/i915_trace.h
> +++ b/drivers/gpu/drm/i915/i915_trace.h
> @@ -233,6 +233,25 @@ TRACE_EVENT(i915_gem_evict_everything,
>  	    TP_printk("dev=%d", __entry->dev)
>  );
>  
> +TRACE_EVENT(i915_gem_ring_sync_to,
> +	    TP_PROTO(struct intel_ring_buffer *from, struct intel_ring_buffer *to),
> +	    TP_ARGS(from, to),
> +
> +	    TP_STRUCT__entry(
> +			     __field(u32, dev)
> +			     __field(u32, sync_from)
> +			     __field(u32, sync_to)
> +			     ),
> +
> +	    TP_fast_assign(
> +			   __entry->dev = from->dev->primary->index;
> +			   __entry->sync_from = from->id;
> +			   __entry->sync_to = to->id;
> +			   ),
> +
> +	    TP_printk("dev=%u, sync-from=%u, sync-to=%u", __entry->dev, __entry->sync_from, __entry->sync_to)
> +);
> +
>  TRACE_EVENT(i915_gem_ring_dispatch,
>  	    TP_PROTO(struct intel_ring_buffer *ring, u32 flags),
>  	    TP_ARGS(ring, flags),
> -- 
> 1.8.1.4
> 
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-- 
Ville Syrjälä
Intel OTC