Re: [RFC] [PATCH 7/7] drm/i915: find guilty batch buffer on ring resets

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Feb 04, 2013 at 04:04:43PM +0200, Mika Kuoppala wrote:
> After hang check timer has declared gpu to be hang,
> rings are reset. In ring reset, when clearing
> request list, do post mortem analysis to find out
> the guilty batch buffer.
> 
> Select requests for further analysis by inspecting
> the completed sequence number which has been updated
> into the HWS page. If request was completed, it can't
> be related to the hang.
> 
> For completed requests mark the batch as guilty
      ^^^^^^^^^

That's a typo, right?

> if the ring was not waiting and the ring head was
> stuck inside the buffer object or in the flush region
> right after the batch. For everything else, mark
> them as innocents.
> 
> Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem.c |   91 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 91 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index b304b06..db0f3e3 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2092,9 +2092,97 @@ i915_gem_request_remove_from_client(struct drm_i915_gem_request *request)
>  	spin_unlock(&file_priv->mm.lock);
>  }
>  
> +static bool i915_head_inside_object(u32 acthd, struct drm_i915_gem_object *obj)
> +{
> +	if (acthd >= obj->gtt_offset &&
> +	    acthd < obj->gtt_offset + obj->base.size)
> +		return true;
> +
> +	return false;
> +}
> +
> +static bool i915_head_inside_request(u32 acthd, u32 rs, u32 re)
> +{
> +	if (rs < re) {
> +		if (acthd >= rs && acthd < re)
> +			return true;
> +	} else if (rs > re) {
> +		if (acthd >= rs || acthd < re)
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
> +static bool i915_request_guilty(struct drm_i915_gem_request *request,
> +				const u32 acthd, bool *inside)
> +{
> +	if (request->batch_obj) {
> +		if (i915_head_inside_object(acthd, request->batch_obj)) {
> +			*inside = true;
> +			return true;
> +		}
> +	}
> +
> +	if (i915_head_inside_request(acthd, request->head, request->tail)) {
> +		*inside = false;
> +		return true;
> +	}
> +
> +	return false;
> +}
> +
> +static void i915_set_reset_status(struct intel_ring_buffer *ring,
> +				  struct drm_i915_gem_request *request,
> +				  u32 acthd)
> +{
> +	bool inside;
> +	struct i915_reset_stats *rs = NULL;
> +	bool guilty;
> +
> +	/* Innocent until proven guilty */
> +	guilty = false;
> +
> +	if (!ring->hangcheck_waiting &&
> +	    i915_request_guilty(request, acthd, &inside)) {
> +		DRM_ERROR("%s hung %s bo (0x%x ctx %d) at 0x%x\n",
> +			  ring->name,
> +			  inside ? "inside" : "flushing",
> +			  request->batch_obj ?
> +			  request->batch_obj->gtt_offset : 0,
> +			  request->ctx ? request->ctx->id : 0,
> +			  acthd);
> +
> +		guilty = true;
> +	}
> +
> +	/* If contexts are disabled or this is the default context, use
> +	 * file_priv->reset_stats
> +	 */
> +	if (request->ctx && request->ctx->id != DEFAULT_CONTEXT_ID)
> +		rs = &request->ctx->reset_stats;
> +	else if (request->file_priv)
> +		rs = &request->file_priv->reset_stats;
> +
> +	if (rs) {
> +		rs->total++;
> +
> +		if (guilty)
> +			rs->guilty++;
> +		else
> +			rs->innocent++;
> +	}
> +}
> +
>  static void i915_gem_reset_ring_lists(struct drm_i915_private *dev_priv,
>  				      struct intel_ring_buffer *ring)
>  {
> +	u32 completed_seqno;
> +	u32 acthd;
> +
> +	acthd = intel_ring_get_active_head(ring);
> +	completed_seqno = ring->get_seqno(ring, false);
> +
>  	while (!list_empty(&ring->request_list)) {
>  		struct drm_i915_gem_request *request;
>  
> @@ -2102,6 +2190,9 @@ static void i915_gem_reset_ring_lists(struct drm_i915_private *dev_priv,
>  					   struct drm_i915_gem_request,
>  					   list);
>  
> +		if (request->seqno > completed_seqno)

i915_seqno_passed()?

> +			i915_set_reset_status(ring, request, acthd);
> +
>  		list_del(&request->list);
>  		i915_gem_request_remove_from_client(request);
>  
> -- 
> 1.7.9.5
> 
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-- 
Ville Syrjälä
Intel OTC