Re: [Intel-gfx] [PATCH 04/31] drm/i915: Move timeslicing flag to scheduler

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

On 08/02/2021 10:52, Chris Wilson wrote:
> Whether a scheduler chooses to implement timeslicing is up to it, and
> not an underlying property of the HW engine. The scheduler does depend
> on the HW supporting preemption.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/gt/intel_engine.h           |  6 ++++++
>   drivers/gpu/drm/i915/gt/intel_engine_types.h     | 16 +++-------------
>   .../gpu/drm/i915/gt/intel_execlists_submission.c |  8 +++++---
>   drivers/gpu/drm/i915/gt/selftest_execlists.c     |  2 +-
>   drivers/gpu/drm/i915/i915_scheduler_types.h      | 10 ++++++++++
>   5 files changed, 25 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine.h b/drivers/gpu/drm/i915/gt/intel_engine.h
> index 875fde52bcb6..5d3bcbfe8f6e 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine.h
> +++ b/drivers/gpu/drm/i915/gt/intel_engine.h
> @@ -280,4 +280,10 @@ intel_engine_flush_scheduler(struct intel_engine_cs *engine)
>   	i915_sched_flush(intel_engine_get_scheduler(engine));
>   }
>   
> +static inline bool
> +intel_engine_has_timeslices(struct intel_engine_cs *engine)
> +{
> +	return i915_sched_has_timeslices(intel_engine_get_scheduler(engine));
> +}
> +
>   #endif /* _INTEL_RINGBUFFER_H_ */
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> index ce5732099815..08bddc5263aa 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> @@ -444,10 +444,9 @@ struct intel_engine_cs {
>   #define I915_ENGINE_SUPPORTS_STATS   BIT(1)
>   #define I915_ENGINE_HAS_PREEMPTION   BIT(2)
>   #define I915_ENGINE_HAS_SEMAPHORES   BIT(3)
> -#define I915_ENGINE_HAS_TIMESLICES   BIT(4)
> -#define I915_ENGINE_IS_VIRTUAL       BIT(5)
> -#define I915_ENGINE_HAS_RELATIVE_MMIO BIT(6)
> -#define I915_ENGINE_REQUIRES_CMD_PARSER BIT(7)
> +#define I915_ENGINE_IS_VIRTUAL       BIT(4)
> +#define I915_ENGINE_HAS_RELATIVE_MMIO BIT(5)
> +#define I915_ENGINE_REQUIRES_CMD_PARSER BIT(6)
>   	unsigned int flags;
>   
>   	/*
> @@ -542,15 +541,6 @@ intel_engine_has_semaphores(const struct intel_engine_cs *engine)
>   	return engine->flags & I915_ENGINE_HAS_SEMAPHORES;
>   }
>   
> -static inline bool
> -intel_engine_has_timeslices(const struct intel_engine_cs *engine)
> -{
> -	if (!IS_ACTIVE(CONFIG_DRM_I915_TIMESLICE_DURATION))
> -		return false;
> -
> -	return engine->flags & I915_ENGINE_HAS_TIMESLICES;
> -}
> -
>   static inline bool
>   intel_engine_is_virtual(const struct intel_engine_cs *engine)
>   {
> diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> index 0f2c3c62cac9..aa1816d28def 100644
> --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> @@ -1025,7 +1025,7 @@ static bool needs_timeslice(const struct intel_engine_cs *engine,
>   {
>   	const struct i915_sched *se = &engine->sched;
>   
> -	if (!intel_engine_has_timeslices(engine))
> +	if (!i915_sched_has_timeslices(se))
>   		return false;
>   
>   	/* If not currently active, or about to switch, wait for next event */
> @@ -2896,8 +2896,6 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
>   		engine->flags |= I915_ENGINE_HAS_SEMAPHORES;
>   		if (can_preempt(engine)) {
>   			engine->flags |= I915_ENGINE_HAS_PREEMPTION;
> -			if (IS_ACTIVE(CONFIG_DRM_I915_TIMESLICE_DURATION))
> -				engine->flags |= I915_ENGINE_HAS_TIMESLICES;
>   		}
>   	}
>   
> @@ -2961,6 +2959,10 @@ static void init_execlists(struct intel_engine_cs *engine)
>   
>   	i915_sched_select_mode(&engine->sched, I915_SCHED_MODE_PRIORITY);
>   
> +	if (IS_ACTIVE(CONFIG_DRM_I915_TIMESLICE_DURATION) &&
> +	    intel_engine_has_preemption(engine))
> +		__set_bit(I915_SCHED_TIMESLICE_BIT, &engine->sched.flags);
> +
>   	timer_setup(&engine->execlists.timer, execlists_timeslice, 0);
>   	timer_setup(&engine->execlists.preempt, execlists_preempt, 0);
>   
> diff --git a/drivers/gpu/drm/i915/gt/selftest_execlists.c b/drivers/gpu/drm/i915/gt/selftest_execlists.c
> index 04ded3a2d491..be99fbd7cfab 100644
> --- a/drivers/gpu/drm/i915/gt/selftest_execlists.c
> +++ b/drivers/gpu/drm/i915/gt/selftest_execlists.c
> @@ -3809,7 +3809,7 @@ static unsigned int
>   __select_siblings(struct intel_gt *gt,
>   		  unsigned int class,
>   		  struct intel_engine_cs **siblings,
> -		  bool (*filter)(const struct intel_engine_cs *))
> +		  bool (*filter)(struct intel_engine_cs *))
>   {
>   	unsigned int n = 0;
>   	unsigned int inst;
> diff --git a/drivers/gpu/drm/i915/i915_scheduler_types.h b/drivers/gpu/drm/i915/i915_scheduler_types.h
> index 2cb46b2e1ac8..3c94378def52 100644
> --- a/drivers/gpu/drm/i915/i915_scheduler_types.h
> +++ b/drivers/gpu/drm/i915/i915_scheduler_types.h
> @@ -12,6 +12,7 @@
>   #include <linux/workqueue.h>
>   
>   #include "i915_priolist_types.h"
> +#include "i915_utils.h"
>   
>   struct drm_printer;
>   struct i915_request;
> @@ -21,6 +22,7 @@ enum {
>   	I915_SCHED_ENABLE_BIT = 0,
>   	I915_SCHED_ACTIVE_BIT, /* can reorder the request flow */
>   	I915_SCHED_PRIORITY_BIT, /* priority sorting of queue */
> +	I915_SCHED_TIMESLICE_BIT, /* multitasking for long workloads */
>   };
>   
>   /**
> @@ -240,4 +242,12 @@ static inline bool i915_sched_has_priorities(const struct i915_sched *se)
>   	return test_bit(I915_SCHED_PRIORITY_BIT, &se->flags);
>   }
>   
> +static inline bool i915_sched_has_timeslices(const struct i915_sched *se)
> +{
> +	if (!IS_ACTIVE(CONFIG_DRM_I915_TIMESLICE_DURATION))
> +		return false;
> +
> +	return test_bit(I915_SCHED_TIMESLICE_BIT, &se->flags);
> +}
> +
>   #endif /* _I915_SCHEDULER_TYPES_H_ */
> 

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

Regards,

Tvrtko
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