[Intel-gfx] [PATCH 4/4] drm/i915: Introduce DRM_I915_THROTTLE_JIFFIES

[Daniel Vetter]

On Thu, May 21, 2015 at 09:01:48PM +0100, Chris Wilson wrote:
> As Daniel commented on
> 
> commit b7ffe1362c5f468b853223acc9268804aa92afc8
> Author: Chris Wilson <chris at chris-wilson.co.uk>
> Date:   Mon Apr 27 13:41:24 2015 +0100
> 
>     drm/i915: Free RPS boosts for all laggards
> 
> it is better to be explicit when sharing hardcoded values such as
> throttle/boost timeouts. Make it so!
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>

I merged patch 1&4 from this to dinq. I'd like a "I want this" for 2. And
3 needs more time to properly review the locking and everything, I'll try
to do that later today.

Thanks, Daniel

> ---
>  drivers/gpu/drm/i915/i915_drv.h | 6 ++++++
>  drivers/gpu/drm/i915/i915_gem.c | 2 +-
>  drivers/gpu/drm/i915/intel_pm.c | 2 +-
>  3 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index abd0914b4849..30ffb9138116 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -279,6 +279,12 @@ struct drm_i915_file_private {
>  	struct {
>  		spinlock_t lock;
>  		struct list_head request_list;
> +/* 20ms is a fairly arbitrary limit (greater than the average frame time)
> + * chosen to prevent the CPU getting more than a frame ahead of the GPU
> + * (when using lax throttling for the frontbuffer). We also use it to
> + * offer free GPU waitboosts for severely congested workloads.
> + */
> +#define DRM_I915_THROTTLE_JIFFIES msecs_to_jiffies(20)
>  	} mm;
>  	struct idr context_idr;
>  
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index ca41fc56f246..9ae98b00ff56 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -4211,7 +4211,7 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	struct drm_i915_file_private *file_priv = file->driver_priv;
> -	unsigned long recent_enough = jiffies - msecs_to_jiffies(20);
> +	unsigned long recent_enough = jiffies - DRM_I915_THROTTLE_JIFFIES;
>  	struct drm_i915_gem_request *request, *target = NULL;
>  	unsigned reset_counter;
>  	int ret;
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 833f9dd28fea..abeb7fca17c8 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -4164,7 +4164,7 @@ void gen6_rps_boost(struct drm_i915_private *dev_priv,
>  	/* Force a RPS boost (and don't count it against the client) if
>  	 * the GPU is severely congested.
>  	 */
> -	if (rps && time_after(jiffies, submitted + msecs_to_jiffies(20)))
> +	if (rps && time_after(jiffies, submitted + DRM_I915_THROTTLE_JIFFIES))
>  		rps = NULL;
>  
>  	spin_lock(&dev_priv->rps.client_lock);
> -- 
> 2.1.4
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch