Message-ID: <20190913174343.GB5387@kevin>
Date:   Fri, 13 Sep 2019 13:43:43 -0400
From:   Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>
To:     Steven Price <steven.price@....com>
Cc:     Daniel Vetter <daniel@...ll.ch>, David Airlie <airlied@...ux.ie>,
        Rob Herring <robh@...nel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Mark Brown <broonie@...nel.org>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] drm/panfrost: Simplify devfreq utilisation tracking

Patch 1 is:

	Acked-by: Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>

Patch 2 is:

	Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>

Good stuff as always!

On Thu, Sep 12, 2019 at 12:28:04PM +0100, Steven Price wrote:
> Instead of tracking per-slot utilisation track a single value for the
> entire GPU. Ultimately it doesn't matter if the GPU is busy with only
> vertex or a combination of vertex and fragment processing - if it's busy
> then it's busy and devfreq should be scaling appropriately.
> 
> This also makes way for being able to submit multiple jobs per slot
> which requires more values than the original boolean per slot.
> 
> Signed-off-by: Steven Price <steven.price@....com>
> ---
>  drivers/gpu/drm/panfrost/panfrost_devfreq.c | 64 ++++++++-------------
>  drivers/gpu/drm/panfrost/panfrost_devfreq.h |  3 +-
>  drivers/gpu/drm/panfrost/panfrost_device.h  | 12 ++--
>  drivers/gpu/drm/panfrost/panfrost_job.c     | 14 ++---
>  4 files changed, 38 insertions(+), 55 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> index 7ded282a5ca8..4c4e8a30a1ac 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> @@ -13,7 +13,7 @@
>  #include "panfrost_gpu.h"
>  #include "panfrost_regs.h"
>  
> -static void panfrost_devfreq_update_utilization(struct panfrost_device *pfdev, int slot);
> +static void panfrost_devfreq_update_utilization(struct panfrost_device *pfdev);
>  
>  static int panfrost_devfreq_target(struct device *dev, unsigned long *freq,
>  				   u32 flags)
> @@ -32,37 +32,23 @@ static int panfrost_devfreq_target(struct device *dev, unsigned long *freq,
>  
>  static void panfrost_devfreq_reset(struct panfrost_device *pfdev)
>  {
> -	ktime_t now = ktime_get();
> -	int i;
> -
> -	for (i = 0; i < NUM_JOB_SLOTS; i++) {
> -		pfdev->devfreq.slot[i].busy_time = 0;
> -		pfdev->devfreq.slot[i].idle_time = 0;
> -		pfdev->devfreq.slot[i].time_last_update = now;
> -	}
> +	pfdev->devfreq.busy_time = 0;
> +	pfdev->devfreq.idle_time = 0;
> +	pfdev->devfreq.time_last_update = ktime_get();
>  }
>  
>  static int panfrost_devfreq_get_dev_status(struct device *dev,
>  					   struct devfreq_dev_status *status)
>  {
>  	struct panfrost_device *pfdev = dev_get_drvdata(dev);
> -	int i;
>  
> -	for (i = 0; i < NUM_JOB_SLOTS; i++) {
> -		panfrost_devfreq_update_utilization(pfdev, i);
> -	}
> +	panfrost_devfreq_update_utilization(pfdev);
>  
>  	status->current_frequency = clk_get_rate(pfdev->clock);
> -	status->total_time = ktime_to_ns(ktime_add(pfdev->devfreq.slot[0].busy_time,
> -						   pfdev->devfreq.slot[0].idle_time));
> -
> -	status->busy_time = 0;
> -	for (i = 0; i < NUM_JOB_SLOTS; i++) {
> -		status->busy_time += ktime_to_ns(pfdev->devfreq.slot[i].busy_time);
> -	}
> +	status->total_time = ktime_to_ns(ktime_add(pfdev->devfreq.busy_time,
> +						   pfdev->devfreq.idle_time));
>  
> -	/* We're scheduling only to one core atm, so don't divide for now */
> -	/* status->busy_time /= NUM_JOB_SLOTS; */
> +	status->busy_time = ktime_to_ns(pfdev->devfreq.busy_time);
>  
>  	panfrost_devfreq_reset(pfdev);
>  
> @@ -134,14 +120,10 @@ void panfrost_devfreq_fini(struct panfrost_device *pfdev)
>  
>  void panfrost_devfreq_resume(struct panfrost_device *pfdev)
>  {
> -	int i;
> -
>  	if (!pfdev->devfreq.devfreq)
>  		return;
>  
>  	panfrost_devfreq_reset(pfdev);
> -	for (i = 0; i < NUM_JOB_SLOTS; i++)
> -		pfdev->devfreq.slot[i].busy = false;
>  
>  	devfreq_resume_device(pfdev->devfreq.devfreq);
>  }
> @@ -154,9 +136,8 @@ void panfrost_devfreq_suspend(struct panfrost_device *pfdev)
>  	devfreq_suspend_device(pfdev->devfreq.devfreq);
>  }
>  
> -static void panfrost_devfreq_update_utilization(struct panfrost_device *pfdev, int slot)
> +static void panfrost_devfreq_update_utilization(struct panfrost_device *pfdev)
>  {
> -	struct panfrost_devfreq_slot *devfreq_slot = &pfdev->devfreq.slot[slot];
>  	ktime_t now;
>  	ktime_t last;
>  
> @@ -164,22 +145,27 @@ static void panfrost_devfreq_update_utilization(struct panfrost_device *pfdev, i
>  		return;
>  
>  	now = ktime_get();
> -	last = pfdev->devfreq.slot[slot].time_last_update;
> +	last = pfdev->devfreq.time_last_update;
>  
> -	/* If we last recorded a transition to busy, we have been idle since */
> -	if (devfreq_slot->busy)
> -		pfdev->devfreq.slot[slot].busy_time += ktime_sub(now, last);
> +	if (atomic_read(&pfdev->devfreq.busy_count) > 0)
> +		pfdev->devfreq.busy_time += ktime_sub(now, last);
>  	else
> -		pfdev->devfreq.slot[slot].idle_time += ktime_sub(now, last);
> +		pfdev->devfreq.idle_time += ktime_sub(now, last);
> +
> +	pfdev->devfreq.time_last_update = now;
> +}
>  
> -	pfdev->devfreq.slot[slot].time_last_update = now;
> +void panfrost_devfreq_record_busy(struct panfrost_device *pfdev)
> +{
> +	panfrost_devfreq_update_utilization(pfdev);
> +	atomic_inc(&pfdev->devfreq.busy_count);
>  }
>  
> -/* The job scheduler is expected to call this at every transition busy <-> idle */
> -void panfrost_devfreq_record_transition(struct panfrost_device *pfdev, int slot)
> +void panfrost_devfreq_record_idle(struct panfrost_device *pfdev)
>  {
> -	struct panfrost_devfreq_slot *devfreq_slot = &pfdev->devfreq.slot[slot];
> +	int count;
>  
> -	panfrost_devfreq_update_utilization(pfdev, slot);
> -	devfreq_slot->busy = !devfreq_slot->busy;
> +	panfrost_devfreq_update_utilization(pfdev);
> +	count = atomic_dec_if_positive(&pfdev->devfreq.busy_count);
> +	WARN_ON(count < 0);
>  }
> diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.h b/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> index e3bc63e82843..0611beffc8d0 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> @@ -10,6 +10,7 @@ void panfrost_devfreq_fini(struct panfrost_device *pfdev);
>  void panfrost_devfreq_resume(struct panfrost_device *pfdev);
>  void panfrost_devfreq_suspend(struct panfrost_device *pfdev);
>  
> -void panfrost_devfreq_record_transition(struct panfrost_device *pfdev, int slot);
> +void panfrost_devfreq_record_busy(struct panfrost_device *pfdev);
> +void panfrost_devfreq_record_idle(struct panfrost_device *pfdev);
>  
>  #endif /* __PANFROST_DEVFREQ_H__ */
> diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
> index 4c2b3c84baac..233957f88d77 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_device.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_device.h
> @@ -51,13 +51,6 @@ struct panfrost_features {
>  	unsigned long hw_issues[64 / BITS_PER_LONG];
>  };
>  
> -struct panfrost_devfreq_slot {
> -	ktime_t busy_time;
> -	ktime_t idle_time;
> -	ktime_t time_last_update;
> -	bool busy;
> -};
> -
>  struct panfrost_device {
>  	struct device *dev;
>  	struct drm_device *ddev;
> @@ -95,7 +88,10 @@ struct panfrost_device {
>  	struct {
>  		struct devfreq *devfreq;
>  		struct thermal_cooling_device *cooling;
> -		struct panfrost_devfreq_slot slot[NUM_JOB_SLOTS];
> +		ktime_t busy_time;
> +		ktime_t idle_time;
> +		ktime_t time_last_update;
> +		atomic_t busy_count;
>  	} devfreq;
>  };
>  
> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
> index 05c85f45a0de..47aeadb4f161 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
> @@ -155,7 +155,7 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
>  
>  	cfg = panfrost_mmu_as_get(pfdev, &job->file_priv->mmu);
>  
> -	panfrost_devfreq_record_transition(pfdev, js);
> +	panfrost_devfreq_record_busy(pfdev);
>  	spin_lock_irqsave(&pfdev->hwaccess_lock, flags);
>  
>  	job_write(pfdev, JS_HEAD_NEXT_LO(js), jc_head & 0xFFFFFFFF);
> @@ -396,7 +396,7 @@ static void panfrost_job_timedout(struct drm_sched_job *sched_job)
>  
>  	/* panfrost_core_dump(pfdev); */
>  
> -	panfrost_devfreq_record_transition(pfdev, js);
> +	panfrost_devfreq_record_idle(pfdev);
>  	panfrost_device_reset(pfdev);
>  
>  	for (i = 0; i < NUM_JOB_SLOTS; i++)
> @@ -454,7 +454,7 @@ static irqreturn_t panfrost_job_irq_handler(int irq, void *data)
>  
>  			pfdev->jobs[j] = NULL;
>  			panfrost_mmu_as_put(pfdev, &job->file_priv->mmu);
> -			panfrost_devfreq_record_transition(pfdev, j);
> +			panfrost_devfreq_record_idle(pfdev);
>  			dma_fence_signal(job->done_fence);
>  		}
>  
> @@ -551,14 +551,14 @@ int panfrost_job_is_idle(struct panfrost_device *pfdev)
>  	struct panfrost_job_slot *js = pfdev->js;
>  	int i;
>  
> +	/* Check whether the hardware is idle */
> +	if (atomic_read(&pfdev->devfreq.busy_count))
> +		return false;
> +
>  	for (i = 0; i < NUM_JOB_SLOTS; i++) {
>  		/* If there are any jobs in the HW queue, we're not idle */
>  		if (atomic_read(&js->queue[i].sched.hw_rq_count))
>  			return false;
> -
> -		/* Check whether the hardware is idle */
> -		if (pfdev->devfreq.slot[i].busy)
> -			return false;
>  	}
>  
>  	return true;
> -- 
> 2.20.1
> 

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