Re: [Intel-gfx] [PATCH 1/2] drm/i915/pmu: Add a name to the execlists stats

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

On Tue, Oct 26, 2021 at 05:48:20PM -0700, Umesh Nerlige Ramappa wrote:
> In preparation for GuC pmu stats, add a name to the execlists stats
> structure so that it can be differentiated from the GuC stats.
> 
> Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_engine_cs.c    | 14 +++---
>  drivers/gpu/drm/i915/gt/intel_engine_stats.h | 33 +++++++------
>  drivers/gpu/drm/i915/gt/intel_engine_types.h | 52 +++++++++++---------
>  3 files changed, 53 insertions(+), 46 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> index ff6753ccb129..2de396e34d83 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> @@ -363,7 +363,7 @@ static int intel_engine_setup(struct intel_gt *gt, enum intel_engine_id id,
>  		DRIVER_CAPS(i915)->has_logical_contexts = true;
>  
>  	ewma__engine_latency_init(&engine->latency);
> -	seqcount_init(&engine->stats.lock);
> +	seqcount_init(&engine->stats.execlists.lock);
>  
>  	ATOMIC_INIT_NOTIFIER_HEAD(&engine->context_status_notifier);
>  
> @@ -1918,15 +1918,16 @@ void intel_engine_dump(struct intel_engine_cs *engine,
>  static ktime_t __intel_engine_get_busy_time(struct intel_engine_cs *engine,
>  					    ktime_t *now)
>  {
> -	ktime_t total = engine->stats.total;
> +	struct intel_engine_execlists_stats *stats = &engine->stats.execlists;
> +	ktime_t total = stats->total;
>  
>  	/*
>  	 * If the engine is executing something at the moment
>  	 * add it to the total.
>  	 */
>  	*now = ktime_get();
> -	if (READ_ONCE(engine->stats.active))
> -		total = ktime_add(total, ktime_sub(*now, engine->stats.start));
> +	if (READ_ONCE(stats->active))
> +		total = ktime_add(total, ktime_sub(*now, stats->start));
>  
>  	return total;
>  }
> @@ -1940,13 +1941,14 @@ static ktime_t __intel_engine_get_busy_time(struct intel_engine_cs *engine,
>   */
>  ktime_t intel_engine_get_busy_time(struct intel_engine_cs *engine, ktime_t *now)
>  {
> +	struct intel_engine_execlists_stats *stats = &engine->stats.execlists;
>  	unsigned int seq;
>  	ktime_t total;
>  
>  	do {
> -		seq = read_seqcount_begin(&engine->stats.lock);
> +		seq = read_seqcount_begin(&stats->lock);
>  		total = __intel_engine_get_busy_time(engine, now);
> -	} while (read_seqcount_retry(&engine->stats.lock, seq));
> +	} while (read_seqcount_retry(&stats->lock, seq));
>  
>  	return total;
>  }
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_stats.h b/drivers/gpu/drm/i915/gt/intel_engine_stats.h
> index 24fbdd94351a..8e762d683e50 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_stats.h
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_stats.h
> @@ -15,45 +15,46 @@
>  
>  static inline void intel_engine_context_in(struct intel_engine_cs *engine)
>  {
> +	struct intel_engine_execlists_stats *stats = &engine->stats.execlists;
>  	unsigned long flags;
>  
> -	if (engine->stats.active) {
> -		engine->stats.active++;
> +	if (stats->active) {
> +		stats->active++;
>  		return;
>  	}
>  
>  	/* The writer is serialised; but the pmu reader may be from hardirq */
>  	local_irq_save(flags);
> -	write_seqcount_begin(&engine->stats.lock);
> +	write_seqcount_begin(&stats->lock);
>  
> -	engine->stats.start = ktime_get();
> -	engine->stats.active++;
> +	stats->start = ktime_get();
> +	stats->active++;
>  
> -	write_seqcount_end(&engine->stats.lock);
> +	write_seqcount_end(&stats->lock);
>  	local_irq_restore(flags);
>  
> -	GEM_BUG_ON(!engine->stats.active);
> +	GEM_BUG_ON(!stats->active);
>  }
>  
>  static inline void intel_engine_context_out(struct intel_engine_cs *engine)
>  {
> +	struct intel_engine_execlists_stats *stats = &engine->stats.execlists;
>  	unsigned long flags;
>  
> -	GEM_BUG_ON(!engine->stats.active);
> -	if (engine->stats.active > 1) {
> -		engine->stats.active--;
> +	GEM_BUG_ON(!stats->active);
> +	if (stats->active > 1) {
> +		stats->active--;
>  		return;
>  	}
>  
>  	local_irq_save(flags);
> -	write_seqcount_begin(&engine->stats.lock);
> +	write_seqcount_begin(&stats->lock);
>  
> -	engine->stats.active--;
> -	engine->stats.total =
> -		ktime_add(engine->stats.total,
> -			  ktime_sub(ktime_get(), engine->stats.start));
> +	stats->active--;
> +	stats->total = ktime_add(stats->total,
> +				 ktime_sub(ktime_get(), stats->start));
>  
> -	write_seqcount_end(&engine->stats.lock);
> +	write_seqcount_end(&stats->lock);
>  	local_irq_restore(flags);
>  }
>  
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> index e0f773585c29..24fa7fb0e7de 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> @@ -257,6 +257,33 @@ struct intel_engine_execlists {
>  
>  #define INTEL_ENGINE_CS_MAX_NAME 8
>  
> +struct intel_engine_execlists_stats {
> +	/**
> +	 * @active: Number of contexts currently scheduled in.
> +	 */
> +	unsigned int active;
> +
> +	/**
> +	 * @lock: Lock protecting the below fields.
> +	 */
> +	seqcount_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;
> +};
> +
>  struct intel_engine_cs {
>  	struct drm_i915_private *i915;
>  	struct intel_gt *gt;
> @@ -488,30 +515,7 @@ struct intel_engine_cs {
>  	u32 (*get_cmd_length_mask)(u32 cmd_header);
>  
>  	struct {
> -		/**
> -		 * @active: Number of contexts currently scheduled in.
> -		 */
> -		unsigned int active;
> -
> -		/**
> -		 * @lock: Lock protecting the below fields.
> -		 */
> -		seqcount_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;
> +		struct intel_engine_execlists_stats execlists;

I'd probably just define this sub-structure inline rather defining it
above. e.g.

struct {
	struct {
		fields...
	} execlists;
} stats;

Then the follow up patch:

union {
	struct {
		fields...
	} execlists;
	struct {
		fields...
	} guc;
} stats;

Or if there is common fields:

struct {
	common fields...
	struct {
		fields...
	} execlists;
	struct {
		fields...
	} guc;
} stats;

That being said, if you prefer to leave it as is, that's fine too.

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

>  
>  		/**
>  		 * @rps: Utilisation at last RPS sampling.
> -- 
> 2.20.1
>