[PATCH v2 2/9] drm/i915/gvt: create a dummy vGPU

[Gao, Ping A]

On 2017/2/14 16:49, Tian, Kevin wrote:
>> From: Ping Gao
>> Sent: Tuesday, February 14, 2017 12:26 PM
>>
>> vGPU execution time is given by scheduler, it decide the resource
>> vGPU could take. Creating a dummy vGPU mainly used to help time
>> slice usage calculation and work as a time slice pool to consume
>> the time slice that real vGPU no need. Besides that it also helpful
>> to handle some special case.
> do we need it even for weight-based scheduling?

Yes, actually weight is another kind of timeslice limitation, e.g.  two
vGPU set weight as 5:2, that means the first vGPUs's max timeslice
cannot exceed 5/(5+2); if both of them become idle, one of them has be
chose as render owner, the time slice usage calculation of render owner
is always go, when idle render owner has workload, the word load cannot
execute timely as the timeslice maybe run out by it's idle status, it's
has to wait for the next second to start, that's a problem here. Beside
that introduce idle vGPU make framework more clearer and the calculation
more easier.

>
> think calling it idle-vGPU might be more meaningful - similar to idle
> vCPU in hypervisor and idle process in OS. :)

Sure, I will chance it to idle_vgpu, just like Xen scheduler use idle_cpu.

>
>> Signed-off-by: Ping Gao <ping.a.gao at intel.com>
>> ---
>>  drivers/gpu/drm/i915/gvt/gvt.c  | 11 +++++++++
>>  drivers/gpu/drm/i915/gvt/gvt.h  |  3 +++
>>  drivers/gpu/drm/i915/gvt/vgpu.c | 51
>> +++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 65 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/gvt/gvt.c b/drivers/gpu/drm/i915/gvt/gvt.c
>> index 3e8c30f..7cd23dc 100644
>> --- a/drivers/gpu/drm/i915/gvt/gvt.c
>> +++ b/drivers/gpu/drm/i915/gvt/gvt.c
>> @@ -201,6 +201,8 @@ void intel_gvt_clean_device(struct drm_i915_private *dev_priv)
>>
>>  	idr_destroy(&gvt->vgpu_idr);
>>
>> +	intel_gvt_destroy_dummy_vgpu(gvt->dummy_vgpu);
>> +
>>  	kfree(dev_priv->gvt);
>>  	dev_priv->gvt = NULL;
>>  }
>> @@ -219,6 +221,7 @@ void intel_gvt_clean_device(struct drm_i915_private *dev_priv)
>>  int intel_gvt_init_device(struct drm_i915_private *dev_priv)
>>  {
>>  	struct intel_gvt *gvt;
>> +	struct intel_vgpu *vgpu;
>>  	int ret;
>>
>>  	/*
>> @@ -291,6 +294,14 @@ int intel_gvt_init_device(struct drm_i915_private *dev_priv)
>>  		goto out_clean_types;
>>  	}
>>
>> +	vgpu = intel_gvt_create_dummy_vgpu(gvt);
>> +	if (IS_ERR_OR_NULL(vgpu)) {
>> +		ret = vgpu == NULL ? -EFAULT : PTR_ERR(vgpu);
> not readable. please split.
>
>> +		gvt_err("failed to create intel dummy vgpu: %d\n", ret);
>> +		goto out_clean_types;
>> +	}
>> +	gvt->dummy_vgpu = vgpu;
>> +
>>  	gvt_dbg_core("gvt device initialization is done\n");
>>  	dev_priv->gvt = gvt;
>>  	return 0;
>> diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h
>> index dae157e..78cbf3c 100644
>> --- a/drivers/gpu/drm/i915/gvt/gvt.h
>> +++ b/drivers/gpu/drm/i915/gvt/gvt.h
>> @@ -235,6 +235,7 @@ struct intel_gvt {
>>  	struct intel_vgpu_type *types;
>>  	unsigned int num_types;
>>  	unsigned int num_vgpu_sched;
>> +	struct intel_vgpu *dummy_vgpu;
>>
>>  	struct task_struct *service_thread;
>>  	wait_queue_head_t service_thread_wq;
>> @@ -375,6 +376,8 @@ static inline void intel_vgpu_write_pci_bar(struct intel_vgpu
>> *vgpu,
>>  int intel_gvt_init_vgpu_types(struct intel_gvt *gvt);
>>  void intel_gvt_clean_vgpu_types(struct intel_gvt *gvt);
>>
>> +struct intel_vgpu *intel_gvt_create_dummy_vgpu(struct intel_gvt *gvt);
>> +void intel_gvt_destroy_dummy_vgpu(struct intel_vgpu *vgpu);
>>  struct intel_vgpu *intel_gvt_create_vgpu(struct intel_gvt *gvt,
>>  					 struct intel_vgpu_type *type);
>>  void intel_gvt_destroy_vgpu(struct intel_vgpu *vgpu);
>> diff --git a/drivers/gpu/drm/i915/gvt/vgpu.c b/drivers/gpu/drm/i915/gvt/vgpu.c
>> index 67d471c..2b0fd13 100644
>> --- a/drivers/gpu/drm/i915/gvt/vgpu.c
>> +++ b/drivers/gpu/drm/i915/gvt/vgpu.c
>> @@ -203,6 +203,57 @@ void intel_gvt_destroy_vgpu(struct intel_vgpu *vgpu)
>>  	mutex_unlock(&gvt->lock);
>>  }
>>
>> +/**
>> + * intel_gvt_create_dummy vgpu - create a dummy virtual GPU
>> + * @gvt: GVT device
>> + *
>> + * This function is called when user wants to create a dummy virtual GPU.
>> + *
>> + * Returns:
>> + * pointer to intel_vgpu, error pointer if failed.
>> + */
>> +struct intel_vgpu *intel_gvt_create_dummy_vgpu(struct intel_gvt *gvt)
>> +{
>> +	struct intel_vgpu *vgpu;
>> +	enum intel_engine_id i;
>> +	int ret;
>> +
>> +	vgpu = vzalloc(sizeof(*vgpu));
>> +	if (!vgpu)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	vgpu->id = 0;
>> +	vgpu->gvt = gvt;
>> +
>> +	for (i = 0; i < I915_NUM_ENGINES; i++)
>> +		INIT_LIST_HEAD(&vgpu->workload_q_head[i]);
>> +
>> +	ret = intel_vgpu_init_sched_policy(vgpu);
>> +	if (ret)
>> +		goto out_free_vgpu;
>> +
>> +	vgpu->active = false;
>> +
>> +	return vgpu;
>> +
>> +out_free_vgpu:
>> +	vfree(vgpu);
>> +	return ERR_PTR(ret);
>> +}
>> +
>> +/**
>> + * intel_gvt_destroy_vgpu - destroy a dummy virtual GPU
>> + * @vgpu: virtual GPU
>> + *
>> + * This function is called when user wants to destroy a dummy virtual GPU.
>> + *
>> + */
>> +void intel_gvt_destroy_dummy_vgpu(struct intel_vgpu *vgpu)
>> +{
>> +	intel_vgpu_clean_sched_policy(vgpu);
>> +	vfree(vgpu);
>> +}
>> +
>>  static struct intel_vgpu *__intel_gvt_create_vgpu(struct intel_gvt *gvt,
>>  		struct intel_vgpu_creation_params *param)
>>  {
>> --
>> 2.7.4
>>
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