Re: [PATCH 1/1] drm/i915: intel_ring_initialized() must be simple and inline

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Dec 08, 2015 at 03:02:36PM +0000, Dave Gordon wrote:
> Based on Chris Wilson's patch from 6 months ago, rebased and adapted.
> 
> The current implementation of intel_ring_initialized() is too heavyweight;
> it's a non-inlined function that chases several levels of pointers. This
> wouldn't matter too much if it were rarely called, but it's used inside
> the iterator test of for_each_ring() and is therefore called quite
> frequently. So let's make it simple and inline ...
> 
> The idea here is to use ring->dev as an indicator showing which engines
> have been initialised and are therefore to be included in iterations that
> use for_each_ring(). This allows us to avoid multiple memory references
> and a (non-inlined) function call on each iteration of each such loop.
> 
> 	Fixes regression from
> 	commit 48d823878d64f93163f5a949623346748bbce1b4
> 	Author: Oscar Mateo <oscar.mateo@intel.com>
> 	Date:   Thu Jul 24 17:04:23 2014 +0100
> 
> 	    drm/i915/bdw: Generic logical ring init and cleanup
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Dave Gordon <david.s.gordon@intel.com>

Queued for -next, thanks for the patch.
-Daniel
> ---
>  drivers/gpu/drm/i915/intel_lrc.c        | 17 +++++++++-----
>  drivers/gpu/drm/i915/intel_ringbuffer.c | 39 +++++++++++----------------------
>  drivers/gpu/drm/i915/intel_ringbuffer.h |  6 ++++-
>  3 files changed, 30 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 4ebafab..7644c48 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -1894,8 +1894,10 @@ void intel_logical_ring_cleanup(struct intel_engine_cs *ring)
>  
>  	dev_priv = ring->dev->dev_private;
>  
> -	intel_logical_ring_stop(ring);
> -	WARN_ON((I915_READ_MODE(ring) & MODE_IDLE) == 0);
> +	if (ring->buffer) {
> +		intel_logical_ring_stop(ring);
> +		WARN_ON((I915_READ_MODE(ring) & MODE_IDLE) == 0);
> +	}
>  
>  	if (ring->cleanup)
>  		ring->cleanup(ring);
> @@ -1909,6 +1911,7 @@ void intel_logical_ring_cleanup(struct intel_engine_cs *ring)
>  	}
>  
>  	lrc_destroy_wa_ctx_obj(ring);
> +	ring->dev = NULL;
>  }
>  
>  static int logical_ring_init(struct drm_device *dev, struct intel_engine_cs *ring)
> @@ -1931,11 +1934,11 @@ static int logical_ring_init(struct drm_device *dev, struct intel_engine_cs *rin
>  
>  	ret = i915_cmd_parser_init_ring(ring);
>  	if (ret)
> -		return ret;
> +		goto error;
>  
>  	ret = intel_lr_context_deferred_alloc(ring->default_context, ring);
>  	if (ret)
> -		return ret;
> +		goto error;
>  
>  	/* As this is the default context, always pin it */
>  	ret = intel_lr_context_do_pin(
> @@ -1946,9 +1949,13 @@ static int logical_ring_init(struct drm_device *dev, struct intel_engine_cs *rin
>  		DRM_ERROR(
>  			"Failed to pin and map ringbuffer %s: %d\n",
>  			ring->name, ret);
> -		return ret;
> +		goto error;
>  	}
>  
> +	return 0;
> +
> +error:
> +	intel_logical_ring_cleanup(ring);
>  	return ret;
>  }
>  
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 57d78f2..921c8a6 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -33,23 +33,6 @@
>  #include "i915_trace.h"
>  #include "intel_drv.h"
>  
> -bool
> -intel_ring_initialized(struct intel_engine_cs *ring)
> -{
> -	struct drm_device *dev = ring->dev;
> -
> -	if (!dev)
> -		return false;
> -
> -	if (i915.enable_execlists) {
> -		struct intel_context *dctx = ring->default_context;
> -		struct intel_ringbuffer *ringbuf = dctx->engine[ring->id].ringbuf;
> -
> -		return ringbuf->obj;
> -	} else
> -		return ring->buffer && ring->buffer->obj;
> -}
> -
>  int __intel_ring_space(int head, int tail, int size)
>  {
>  	int space = head - tail;
> @@ -2167,8 +2150,10 @@ static int intel_init_ring_buffer(struct drm_device *dev,
>  	init_waitqueue_head(&ring->irq_queue);
>  
>  	ringbuf = intel_engine_create_ringbuffer(ring, 32 * PAGE_SIZE);
> -	if (IS_ERR(ringbuf))
> -		return PTR_ERR(ringbuf);
> +	if (IS_ERR(ringbuf)) {
> +		ret = PTR_ERR(ringbuf);
> +		goto error;
> +	}
>  	ring->buffer = ringbuf;
>  
>  	if (I915_NEED_GFX_HWS(dev)) {
> @@ -2197,8 +2182,7 @@ static int intel_init_ring_buffer(struct drm_device *dev,
>  	return 0;
>  
>  error:
> -	intel_ringbuffer_free(ringbuf);
> -	ring->buffer = NULL;
> +	intel_cleanup_ring_buffer(ring);
>  	return ret;
>  }
>  
> @@ -2211,12 +2195,14 @@ void intel_cleanup_ring_buffer(struct intel_engine_cs *ring)
>  
>  	dev_priv = to_i915(ring->dev);
>  
> -	intel_stop_ring_buffer(ring);
> -	WARN_ON(!IS_GEN2(ring->dev) && (I915_READ_MODE(ring) & MODE_IDLE) == 0);
> +	if (ring->buffer) {
> +		intel_stop_ring_buffer(ring);
> +		WARN_ON(!IS_GEN2(ring->dev) && (I915_READ_MODE(ring) & MODE_IDLE) == 0);
>  
> -	intel_unpin_ringbuffer_obj(ring->buffer);
> -	intel_ringbuffer_free(ring->buffer);
> -	ring->buffer = NULL;
> +		intel_unpin_ringbuffer_obj(ring->buffer);
> +		intel_ringbuffer_free(ring->buffer);
> +		ring->buffer = NULL;
> +	}
>  
>  	if (ring->cleanup)
>  		ring->cleanup(ring);
> @@ -2225,6 +2211,7 @@ void intel_cleanup_ring_buffer(struct intel_engine_cs *ring)
>  
>  	i915_cmd_parser_fini_ring(ring);
>  	i915_gem_batch_pool_fini(&ring->batch_pool);
> +	ring->dev = NULL;
>  }
>  
>  static int ring_wait_for_space(struct intel_engine_cs *ring, int n)
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
> index 5d1eb20..49574ff 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.h
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
> @@ -350,7 +350,11 @@ struct  intel_engine_cs {
>  	u32 (*get_cmd_length_mask)(u32 cmd_header);
>  };
>  
> -bool intel_ring_initialized(struct intel_engine_cs *ring);
> +static inline bool
> +intel_ring_initialized(struct intel_engine_cs *ring)
> +{
> +	return ring->dev != NULL;
> +}
>  
>  static inline unsigned
>  intel_ring_flag(struct intel_engine_cs *ring)
> -- 
> 1.9.1
> 
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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