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SubjectRe: [PATCH 2/2] drm/panfrost: Simplify devfreq utilisation tracking
Patch 1 is:

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

Patch 2 is:

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.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@arm.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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