Re: [Intel-gfx] [PATCH 12/20] drm/i915/gt: Track the overall awake/busy time

[Matthew Brost <matthew.brost@intel.com>]

On Mon, Dec 07, 2020 at 07:38:16PM +0000, Chris Wilson wrote:
> Since we wake the GT up before executing a request, and go to sleep as
> soon as it is retired, the GT wake time not only represents how long the
> device is powered up, but also provides a summary, albeit an overestimate,
> of the device runtime (i.e. the rc0 time to compare against rc6 time).
> 
> v2: s/busy/awake/
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/gt/debugfs_gt_pm.c  |  5 ++-
>  drivers/gpu/drm/i915/gt/intel_gt_pm.c    | 49 ++++++++++++++++++++++++
>  drivers/gpu/drm/i915/gt/intel_gt_pm.h    |  2 +
>  drivers/gpu/drm/i915/gt/intel_gt_types.h | 24 ++++++++++++
>  drivers/gpu/drm/i915/i915_debugfs.c      |  5 ++-
>  drivers/gpu/drm/i915/i915_pmu.c          |  6 +++
>  include/uapi/drm/i915_drm.h              |  1 +
>  7 files changed, 89 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/debugfs_gt_pm.c b/drivers/gpu/drm/i915/gt/debugfs_gt_pm.c
> index 174a24553322..8975717ace06 100644
> --- a/drivers/gpu/drm/i915/gt/debugfs_gt_pm.c
> +++ b/drivers/gpu/drm/i915/gt/debugfs_gt_pm.c
> @@ -11,6 +11,7 @@
>  #include "i915_drv.h"
>  #include "intel_gt.h"
>  #include "intel_gt_clock_utils.h"
> +#include "intel_gt_pm.h"
>  #include "intel_llc.h"
>  #include "intel_rc6.h"
>  #include "intel_rps.h"
> @@ -558,7 +559,9 @@ static int rps_boost_show(struct seq_file *m, void *data)
>  
>  	seq_printf(m, "RPS enabled? %s\n", yesno(intel_rps_is_enabled(rps)));
>  	seq_printf(m, "RPS active? %s\n", yesno(intel_rps_is_active(rps)));
> -	seq_printf(m, "GPU busy? %s\n", yesno(gt->awake));
> +	seq_printf(m, "GPU busy? %s, %llums\n",
> +		   yesno(gt->awake),
> +		   ktime_to_ms(intel_gt_get_awake_time(gt)));

I think it would be useful to print the total time the gt has been alive
too. This would give a nice comparison to total awake time which you
print here. Should be easy enough to do.

>  	seq_printf(m, "Boosts outstanding? %d\n",
>  		   atomic_read(&rps->num_waiters));
>  	seq_printf(m, "Interactive? %d\n", READ_ONCE(rps->power.interactive));
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> index 274aa0dd7050..c94e8ac884eb 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> @@ -39,6 +39,28 @@ static void user_forcewake(struct intel_gt *gt, bool suspend)
>  	intel_gt_pm_put(gt);
>  }
>  
> +static void runtime_begin(struct intel_gt *gt)
> +{
> +	local_irq_disable();
> +	write_seqcount_begin(&gt->stats.lock);
> +	gt->stats.start = ktime_get();
> +	gt->stats.active = true;
> +	write_seqcount_end(&gt->stats.lock);
> +	local_irq_enable();
> +}
> +
> +static void runtime_end(struct intel_gt *gt)
> +{
> +	local_irq_disable();
> +	write_seqcount_begin(&gt->stats.lock);
> +	gt->stats.active = false;
> +	gt->stats.total =
> +		ktime_add(gt->stats.total,
> +			  ktime_sub(ktime_get(), gt->stats.start));
> +	write_seqcount_end(&gt->stats.lock);
> +	local_irq_enable();
> +}
> +
>  static int __gt_unpark(struct intel_wakeref *wf)
>  {
>  	struct intel_gt *gt = container_of(wf, typeof(*gt), wakeref);
> @@ -67,6 +89,7 @@ static int __gt_unpark(struct intel_wakeref *wf)
>  	i915_pmu_gt_unparked(i915);
>  
>  	intel_gt_unpark_requests(gt);
> +	runtime_begin(gt);
>  
>  	return 0;
>  }
> @@ -79,6 +102,7 @@ static int __gt_park(struct intel_wakeref *wf)
>  
>  	GT_TRACE(gt, "\n");
>  
> +	runtime_end(gt);
>  	intel_gt_park_requests(gt);
>  
>  	i915_vma_parked(gt);
> @@ -106,6 +130,7 @@ static const struct intel_wakeref_ops wf_ops = {
>  void intel_gt_pm_init_early(struct intel_gt *gt)
>  {
>  	intel_wakeref_init(&gt->wakeref, gt->uncore->rpm, &wf_ops);
> +	seqcount_mutex_init(&gt->stats.lock, &gt->wakeref.mutex);
>  }
>  
>  void intel_gt_pm_init(struct intel_gt *gt)
> @@ -339,6 +364,30 @@ int intel_gt_runtime_resume(struct intel_gt *gt)
>  	return intel_uc_runtime_resume(&gt->uc);
>  }
>  
> +static ktime_t __intel_gt_get_awake_time(const struct intel_gt *gt)
> +{
> +	ktime_t total = gt->stats.total;
> +
> +	if (gt->stats.active)
> +		total = ktime_add(total,
> +				  ktime_sub(ktime_get(), gt->stats.start));
> +
> +	return total;
> +}
> +
> +ktime_t intel_gt_get_awake_time(const struct intel_gt *gt)
> +{
> +	unsigned int seq;
> +	ktime_t total;
> +
> +	do {
> +		seq = read_seqcount_begin(&gt->stats.lock);
> +		total = __intel_gt_get_awake_time(gt);
> +	} while (read_seqcount_retry(&gt->stats.lock, seq));
> +
> +	return total;
> +}
> +
>  #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
>  #include "selftest_gt_pm.c"
>  #endif
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.h b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
> index 60f0e2fbe55c..63846a856e7e 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.h
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
> @@ -58,6 +58,8 @@ int intel_gt_resume(struct intel_gt *gt);
>  void intel_gt_runtime_suspend(struct intel_gt *gt);
>  int intel_gt_runtime_resume(struct intel_gt *gt);
>  
> +ktime_t intel_gt_get_awake_time(const struct intel_gt *gt);
> +
>  static inline bool is_mock_gt(const struct intel_gt *gt)
>  {
>  	return I915_SELFTEST_ONLY(gt->awake == -ENODEV);
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_types.h b/drivers/gpu/drm/i915/gt/intel_gt_types.h
> index 6d39a4a11bf3..c7bde529feab 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_types.h
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_types.h
> @@ -87,6 +87,30 @@ struct intel_gt {
>  
>  	u32 pm_guc_events;
>  
> +	struct {
> +		bool active;
> +
> +		/**
> +		 * @lock: Lock protecting the below fields.
> +		 */
> +		seqcount_mutex_t lock;
> +
> +		/**
> +		 * @total: Total time this engine was busy.
> +		 *
> +		 * Accumulated time not counting the most recent block in cases
> +		 * where engine is currently busy (active > 0).
> +		 */
> +		ktime_t total;
> +
> +		/**
> +		 * @start: Timestamp of the last idle to active transition.
> +		 *
> +		 * Idle is defined as active == 0, active is active > 0.
> +		 */
> +		ktime_t start;
> +	} stats;
> +
>  	struct intel_engine_cs *engine[I915_NUM_ENGINES];
>  	struct intel_engine_cs *engine_class[MAX_ENGINE_CLASS + 1]
>  					    [MAX_ENGINE_INSTANCE + 1];
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index f48df3545e39..c72160e3702f 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -858,9 +858,10 @@ static int i915_engine_info(struct seq_file *m, void *unused)
>  
>  	wakeref = intel_runtime_pm_get(&i915->runtime_pm);
>  
> -	seq_printf(m, "GT awake? %s [%d]\n",
> +	seq_printf(m, "GT awake? %s [%d], %llums\n",
>  		   yesno(i915->gt.awake),
> -		   atomic_read(&i915->gt.wakeref.count));
> +		   atomic_read(&i915->gt.wakeref.count),
> +		   ktime_to_ms(intel_gt_get_awake_time(&i915->gt)));

Same here as above.

With that nit:
Reviewed-by: Matthew Brost <matthew.brost@intel.com>

>  	seq_printf(m, "CS timestamp frequency: %u Hz\n",
>  		   RUNTIME_INFO(i915)->cs_timestamp_frequency_hz);
>  
> diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> index 97bb4aaa5236..fc762eec9601 100644
> --- a/drivers/gpu/drm/i915/i915_pmu.c
> +++ b/drivers/gpu/drm/i915/i915_pmu.c
> @@ -516,6 +516,8 @@ config_status(struct drm_i915_private *i915, u64 config)
>  		if (!HAS_RC6(i915))
>  			return -ENODEV;
>  		break;
> +	case I915_PMU_GT_AWAKE:
> +		break;
>  	default:
>  		return -ENOENT;
>  	}
> @@ -623,6 +625,9 @@ static u64 __i915_pmu_event_read(struct perf_event *event)
>  		case I915_PMU_RC6_RESIDENCY:
>  			val = get_rc6(&i915->gt);
>  			break;
> +		case I915_PMU_GT_AWAKE:
> +			val = ktime_to_ns(intel_gt_get_awake_time(&i915->gt));
> +			break;
>  		}
>  	}
>  
> @@ -938,6 +943,7 @@ create_event_attributes(struct i915_pmu *pmu)
>  		__event(I915_PMU_REQUESTED_FREQUENCY, "requested-frequency", "M"),
>  		__event(I915_PMU_INTERRUPTS, "interrupts", NULL),
>  		__event(I915_PMU_RC6_RESIDENCY, "rc6-residency", "ns"),
> +		__event(I915_PMU_GT_AWAKE, "awake", "ns"),
>  	};
>  	static const struct {
>  		enum drm_i915_pmu_engine_sample sample;
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 6edcb2b6c708..04abd1ee89bf 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -177,6 +177,7 @@ enum drm_i915_pmu_engine_sample {
>  #define I915_PMU_REQUESTED_FREQUENCY	__I915_PMU_OTHER(1)
>  #define I915_PMU_INTERRUPTS		__I915_PMU_OTHER(2)
>  #define I915_PMU_RC6_RESIDENCY		__I915_PMU_OTHER(3)
> +#define I915_PMU_GT_AWAKE		__I915_PMU_OTHER(4)
>  
>  #define I915_PMU_LAST /* Deprecated - do not use */ I915_PMU_RC6_RESIDENCY
>  
> -- 
> 2.20.1
> 
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