[PATCH 3/3] drm/i915/gvt: [small locks] use scheduler lock

Zhenyu Wang zhenyuw at linux.intel.com
Thu Jan 25 07:22:55 UTC 2018


On 2018.01.25 15:09:27 +0800, pei.zhang at intel.com wrote:
> From: Pei Zhang <pei.zhang at intel.com>
> 
> The scheduler lock(gvt->sched_lock) is used to protect gvt
> scheduler logic, including the gvt scheduler structure(gvt->scheduler
> and per vgpu schedule data(vgpu->sched_data, vgpu->sched_ctl).
> 
> Signed-off-by: Pei Zhang <pei.zhang at intel.com>
> ---
>  drivers/gpu/drm/i915/gvt/display.c      |  3 ---
>  drivers/gpu/drm/i915/gvt/gvt.c          |  1 +
>  drivers/gpu/drm/i915/gvt/gvt.h          |  7 ++++++
>  drivers/gpu/drm/i915/gvt/sched_policy.c | 41 ++++++++++++++++++++++++++++-----
>  drivers/gpu/drm/i915/gvt/scheduler.c    |  8 +++----
>  5 files changed, 47 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/display.c b/drivers/gpu/drm/i915/gvt/display.c
> index 84197d3..8042fc1 100644
> --- a/drivers/gpu/drm/i915/gvt/display.c
> +++ b/drivers/gpu/drm/i915/gvt/display.c
> @@ -328,9 +328,6 @@ void intel_gvt_check_vblank_emulation(struct intel_gvt *gvt)
>  	struct intel_vgpu *vgpu;
>  	int pipe, id;
>  
> -	if (WARN_ON(!mutex_is_locked(&gvt->lock)))
> -		return;
> -
>  	for_each_active_vgpu(gvt, vgpu, id) {
>  		for (pipe = 0; pipe < I915_MAX_PIPES; pipe++) {
>  			if (pipe_is_enabled(vgpu, pipe))

This is not for sched lock, looks should be in last patch, and as we
check all active vgpu here, still requires gvt lock for that purpose.

> diff --git a/drivers/gpu/drm/i915/gvt/gvt.c b/drivers/gpu/drm/i915/gvt/gvt.c
> index d8d5e6c..b119c53 100644
> --- a/drivers/gpu/drm/i915/gvt/gvt.c
> +++ b/drivers/gpu/drm/i915/gvt/gvt.c
> @@ -377,6 +377,7 @@ int intel_gvt_init_device(struct drm_i915_private *dev_priv)
>  	spin_lock_init(&gvt->scheduler.mmio_context_lock);
>  	mutex_init(&gvt->lock);
>  	mutex_init(&gvt->gtt_lock);
> +	mutex_init(&gvt->sched_lock);
>  	gvt->dev_priv = dev_priv;
>  
>  	init_device_info(gvt);
> diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h
> index 76f6c24..1997419 100644
> --- a/drivers/gpu/drm/i915/gvt/gvt.h
> +++ b/drivers/gpu/drm/i915/gvt/gvt.h
> @@ -181,6 +181,11 @@ struct intel_vgpu {
>  	bool pv_notified;
>  	bool failsafe;
>  	unsigned int resetting_eng;
> +
> +	/* both sched_data and sched_ctl can be seen a part of the global gvt
> +	 * scheduler structure. So these 2 vgpu data are protected by gvt->sched_lock,
> +	 * not vgpu->vgpu_lock.
> +	 * */
>  	void *sched_data;
>  
>  	struct vgpu_sched_ctl sched_ctl;
> @@ -295,6 +300,8 @@ struct intel_gvt {
>  	 */
>  	struct mutex lock;
>  	struct mutex gtt_lock;
> +	/* scheduler scope lock, protect gvt and vgpu schedule related data */
> +	struct mutex sched_lock;
>  
>  	struct drm_i915_private *dev_priv;
>  	struct idr vgpu_idr;	/* vGPU IDR pool */
> diff --git a/drivers/gpu/drm/i915/gvt/sched_policy.c b/drivers/gpu/drm/i915/gvt/sched_policy.c
> index d031f64..f78fa21 100644
> --- a/drivers/gpu/drm/i915/gvt/sched_policy.c
> +++ b/drivers/gpu/drm/i915/gvt/sched_policy.c
> @@ -228,8 +228,9 @@ void intel_gvt_schedule(struct intel_gvt *gvt)
>  	struct gvt_sched_data *sched_data = gvt->scheduler.sched_data;
>  	static uint64_t timer_check;
>  
> -	mutex_lock(&gvt->lock);
> -
> +	/* Don't use external lock to protect service_request.
> +	 * Instead, always use atomic bit ops on it.
> +	 */
>  	if (test_and_clear_bit(INTEL_GVT_REQUEST_SCHED,
>  				(void *)&gvt->service_request)) {
>  		if (!(timer_check++ % GVT_TS_BALANCE_PERIOD_MS))
> @@ -237,9 +238,9 @@ void intel_gvt_schedule(struct intel_gvt *gvt)
>  	}
>  	clear_bit(INTEL_GVT_REQUEST_EVENT_SCHED, (void *)&gvt->service_request);
>  
> +	mutex_lock(&gvt->sched_lock);
>  	tbs_sched_func(sched_data);
> -
> -	mutex_unlock(&gvt->lock);
> +	mutex_unlock(&gvt->sched_lock);
>  }
>  
>  static enum hrtimer_restart tbs_timer_fn(struct hrtimer *timer_data)
> @@ -352,36 +353,62 @@ static struct intel_gvt_sched_policy_ops tbs_schedule_ops = {
>  
>  int intel_gvt_init_sched_policy(struct intel_gvt *gvt)
>  {
> +	int ret;
> +
> +	mutex_lock(&gvt->sched_lock);
>  	gvt->scheduler.sched_ops = &tbs_schedule_ops;
> +	ret = gvt->scheduler.sched_ops->init(gvt);
> +	mutex_unlock(&gvt->sched_lock);
>  
> -	return gvt->scheduler.sched_ops->init(gvt);
> +	return ret;
>  }
>  
>  void intel_gvt_clean_sched_policy(struct intel_gvt *gvt)
>  {
> +	mutex_lock(&gvt->sched_lock);
>  	gvt->scheduler.sched_ops->clean(gvt);
> +	mutex_unlock(&gvt->sched_lock);
>  }
>  
> +/* for per-vgpu scheduler policy, there are 2 per-vgpu data:
> + * sched_data, and sched_ctl. We see these 2 data as part of
> + * the global scheduler which are proteced by gvt->sched_lock.
> + * Caller should make their decision if the vgpu_lock should
> + * be hold outside.
> + */
> +
>  int intel_vgpu_init_sched_policy(struct intel_vgpu *vgpu)
>  {
> -	return vgpu->gvt->scheduler.sched_ops->init_vgpu(vgpu);
> +	int ret;
> +
> +	mutex_lock(&vgpu->gvt->sched_lock);
> +	ret = vgpu->gvt->scheduler.sched_ops->init_vgpu(vgpu);
> +	mutex_unlock(&vgpu->gvt->sched_lock);
> +
> +	return ret;
>  }
>  
>  void intel_vgpu_clean_sched_policy(struct intel_vgpu *vgpu)
>  {
> +	mutex_lock(&vgpu->gvt->sched_lock);
>  	vgpu->gvt->scheduler.sched_ops->clean_vgpu(vgpu);
> +	mutex_unlock(&vgpu->gvt->sched_lock);
>  }
>  
>  void intel_vgpu_start_schedule(struct intel_vgpu *vgpu)
>  {
>  	gvt_dbg_core("vgpu%d: start schedule\n", vgpu->id);
>  
> +	mutex_lock(&vgpu->gvt->sched_lock);
>  	vgpu->gvt->scheduler.sched_ops->start_schedule(vgpu);
> +	mutex_unlock(&vgpu->gvt->sched_lock);
>  }
>  
>  void intel_gvt_kick_schedule(struct intel_gvt *gvt)
>  {
> +	mutex_lock(&gvt->sched_lock);
>  	intel_gvt_request_service(gvt, INTEL_GVT_REQUEST_EVENT_SCHED);
> +	mutex_unlock(&gvt->sched_lock);
>  }
>  
>  void intel_vgpu_stop_schedule(struct intel_vgpu *vgpu)
> @@ -392,6 +419,7 @@ void intel_vgpu_stop_schedule(struct intel_vgpu *vgpu)
>  
>  	gvt_dbg_core("vgpu%d: stop schedule\n", vgpu->id);
>  
> +	mutex_lock(&vgpu->gvt->sched_lock);
>  	scheduler->sched_ops->stop_schedule(vgpu);
>  
>  	if (scheduler->next_vgpu == vgpu)
> @@ -411,4 +439,5 @@ void intel_vgpu_stop_schedule(struct intel_vgpu *vgpu)
>  		}
>  	}
>  	spin_unlock_bh(&scheduler->mmio_context_lock);
> +	mutex_unlock(&vgpu->gvt->sched_lock);
>  }
> diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
> index 907195a..f1b191d 100644
> --- a/drivers/gpu/drm/i915/gvt/scheduler.c
> +++ b/drivers/gpu/drm/i915/gvt/scheduler.c
> @@ -602,7 +602,7 @@ static struct intel_vgpu_workload *pick_next_workload(
>  	struct intel_gvt_workload_scheduler *scheduler = &gvt->scheduler;
>  	struct intel_vgpu_workload *workload = NULL;
>  
> -	mutex_lock(&gvt->lock);
> +	mutex_lock(&gvt->sched_lock);
>  
>  	/*
>  	 * no current vgpu / will be scheduled out / no workload
> @@ -648,7 +648,7 @@ static struct intel_vgpu_workload *pick_next_workload(
>  
>  	atomic_inc(&workload->vgpu->submission.running_workload_num);
>  out:
> -	mutex_unlock(&gvt->lock);
> +	mutex_unlock(&gvt->sched_lock);
>  	return workload;
>  }
>  
> @@ -749,8 +749,8 @@ static void complete_current_workload(struct intel_gvt *gvt, int ring_id)
>  	struct intel_vgpu_submission *s = &vgpu->submission;
>  	int event;
>  
> -	mutex_lock(&gvt->lock);
>  	mutex_lock(&vgpu->vgpu_lock);
> +	mutex_lock(&gvt->sched_lock);
>  
>  	/* For the workload w/ request, needs to wait for the context
>  	 * switch to make sure request is completed.
> @@ -828,8 +828,8 @@ static void complete_current_workload(struct intel_gvt *gvt, int ring_id)
>  	if (gvt->scheduler.need_reschedule)
>  		intel_gvt_request_service(gvt, INTEL_GVT_REQUEST_EVENT_SCHED);
>  
> +	mutex_unlock(&gvt->sched_lock);
>  	mutex_unlock(&vgpu->vgpu_lock);
> -	mutex_unlock(&gvt->lock);
>  }
>  
>  struct workload_thread_param {
> -- 
> 2.7.4
> 

-- 
Open Source Technology Center, Intel ltd.

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