Re: [PATCH 1/2] drm/i915: Track the number of times we have woken the GPU up

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

On 19/01/2018 15:23, Chris Wilson wrote:
> By counting the number of times we have woken up, we have a very simple
> means of defining an epoch, which will come in handy if we want to
> perform deferred tasks at the end of an epoch (i.e. while we are going
> to sleep) without imposing on the next activity cycle.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_debugfs.c     | 7 ++++---
>   drivers/gpu/drm/i915/i915_drv.h         | 5 +++++
>   drivers/gpu/drm/i915/i915_gem_request.c | 1 +
>   3 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index cc659b4b2a45..1aac3ec7d14d 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -2717,7 +2717,8 @@ static int i915_runtime_pm_status(struct seq_file *m, void *unused)
>   	if (!HAS_RUNTIME_PM(dev_priv))
>   		seq_puts(m, "Runtime power management not supported\n");
>   
> -	seq_printf(m, "GPU idle: %s\n", yesno(!dev_priv->gt.awake));
> +	seq_printf(m, "GPU idle: %s (epoch %d)\n",
> +		   yesno(!dev_priv->gt.awake), dev_priv->gt.epoch);
>   	seq_printf(m, "IRQs disabled: %s\n",
>   		   yesno(!intel_irqs_enabled(dev_priv)));
>   #ifdef CONFIG_PM
> @@ -3150,8 +3151,8 @@ static int i915_engine_info(struct seq_file *m, void *unused)
>   
>   	intel_runtime_pm_get(dev_priv);
>   
> -	seq_printf(m, "GT awake? %s\n",
> -		   yesno(dev_priv->gt.awake));
> +	seq_printf(m, "GT awake? %s (epoch %d)\n",
> +		   yesno(dev_priv->gt.awake), dev_priv->gt.epoch);
>   	seq_printf(m, "Global active requests: %d\n",
>   		   dev_priv->gt.active_requests);
>   	seq_printf(m, "CS timestamp frequency: %u kHz\n",
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 317953484fec..98e8385d1bb0 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2302,6 +2302,11 @@ struct drm_i915_private {
>   		struct i915_gem_timeline global_timeline;
>   		u32 active_requests;
>   
> +		/**
> +		 * The number of times we have woken up.
> +		 */
> +		u32 epoch;
> +
>   		/**
>   		 * Is the GPU currently considered idle, or busy executing
>   		 * userspace requests? Whilst idle, we allow runtime power
> diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
> index a0f451b4a4e8..f0fab070a3a0 100644
> --- a/drivers/gpu/drm/i915/i915_gem_request.c
> +++ b/drivers/gpu/drm/i915/i915_gem_request.c
> @@ -274,6 +274,7 @@ static void mark_busy(struct drm_i915_private *i915)
>   	intel_display_power_get(i915, POWER_DOMAIN_GT_IRQ);
>   
>   	i915->gt.awake = true;
> +	i915->gt.epoch++;
>   
>   	intel_enable_gt_powersave(i915);
>   	i915_update_gfx_val(i915);
> 

I'd be tempted to use a standard type like unsigned int where explicit 
width is not needed but it's minor.

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko

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