[PATCH v5 3/8] drm/i915/gvt: factor out the scheduler

[Tian, Kevin]

> From: Ping Gao
> Sent: Tuesday, March 28, 2017 2:48 PM
> 
> Factor out the scheduler to a more clear structure, the basic logic is to find
> out next vGPU first and then schedule it. When deciding to pick up who is the
> next vGPU it includes two steps: first is to find out a vGPU who has urgent
> requirement as it's near TDR because of out-of-service for a long time,
> second is to choose the vGPU who has pending workload follow round-robin

'follow' -> 'in'

> style.
> 
> Signed-off-by: Ping Gao <ping.a.gao at intel.com>

Reviewed-by: Kevin Tian <kevin.tian at intel.com> with some comment fix below.

> ---
>  drivers/gpu/drm/i915/gvt/sched_policy.c | 76 ++++++++++++++++++++++++-
> --------
>  1 file changed, 57 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/sched_policy.c
> b/drivers/gpu/drm/i915/gvt/sched_policy.c
> index 3a1fe38..c6523b9 100644
> --- a/drivers/gpu/drm/i915/gvt/sched_policy.c
> +++ b/drivers/gpu/drm/i915/gvt/sched_policy.c
> @@ -118,28 +118,12 @@ static void try_to_schedule_next_vgpu(struct
> intel_gvt *gvt)
>  		wake_up(&scheduler->waitq[i]);
>  }
> 
> -#define GVT_DEFAULT_TIME_SLICE 1000000
> -
> -static void tbs_sched_func(struct gvt_sched_data *sched_data)
> +static struct intel_vgpu *find_busy_vgpu(struct list_head *head,
> +					struct gvt_sched_data *sched_data)
>  {
>  	struct vgpu_sched_data *vgpu_data;
> -
> -	struct intel_gvt *gvt = sched_data->gvt;
> -	struct intel_gvt_workload_scheduler *scheduler = &gvt->scheduler;
> -
>  	struct intel_vgpu *vgpu = NULL;
> -	struct list_head *pos, *head;
> -
> -	/* no vgpu or has already had a target */
> -	if (list_empty(&sched_data->runq_head) || scheduler->next_vgpu)
> -		goto out;
> -
> -	if (scheduler->current_vgpu) {
> -		vgpu_data = scheduler->current_vgpu->sched_data;
> -		head = &vgpu_data->list;
> -	} else {
> -		head = &sched_data->runq_head;
> -	}
> +	struct list_head *pos;
> 
>  	/* search a vgpu with pending workload */
>  	list_for_each(pos, head) {
> @@ -154,6 +138,60 @@ static void tbs_sched_func(struct gvt_sched_data
> *sched_data)
>  		break;
>  	}
> 
> +	return vgpu;
> +}
> +
> +static struct list_head *get_sched_head(struct gvt_sched_data
> +*sched_data) {
> +	struct intel_gvt *gvt = sched_data->gvt;
> +	struct intel_gvt_workload_scheduler *scheduler = &gvt->scheduler;
> +	struct vgpu_sched_data *cur_vgpu_data;
> +	struct list_head *head;
> +
> +	if (scheduler->current_vgpu) {
> +		cur_vgpu_data = scheduler->current_vgpu->sched_data;
> +		head = &cur_vgpu_data->list;
> +	} else {
> +		gvt_dbg_sched("no current vgpu search from q head\n");
> +		head = &sched_data->runq_head;
> +	}
> +
> +	return head;
> +}
> +
> +static struct intel_vgpu *pickup_next_vgpu(struct gvt_sched_data
> +*sched_data) {
> +	struct intel_vgpu *next_vgpu = NULL;
> +	struct list_head *head = NULL;
> +
> +	/* The scheduler follows round-robin style, sched
> +	 * head means where start to choose next vGPU, it's
> +	 * help to decide which vGPU is first one in the

help -> helpful

> +	 * round-robin queue at this schedule check point,
> +	 * that's important to keep fairness.
> +	 */
> +	head = get_sched_head(sched_data);
> +
> +	/* Choose the vGPU which has pending workload. */
> +	next_vgpu = find_busy_vgpu(head, sched_data);
> +
> +	return next_vgpu;
> +}
> +
> +#define GVT_DEFAULT_TIME_SLICE 1000000
> +
> +static void tbs_sched_func(struct gvt_sched_data *sched_data) {
> +	struct intel_gvt *gvt = sched_data->gvt;
> +	struct intel_gvt_workload_scheduler *scheduler = &gvt->scheduler;
> +	struct intel_vgpu *vgpu = NULL;
> +
> +	/* no active vgpu or has already had a target */
> +	if (list_empty(&sched_data->runq_head) || scheduler->next_vgpu)
> +		goto out;
> +
> +	/* determine which vGPU should choose as next */

useless comment

> +	vgpu = pickup_next_vgpu(sched_data);
>  	if (vgpu) {
>  		scheduler->next_vgpu = vgpu;
>  		gvt_dbg_sched("pick next vgpu %d\n", vgpu->id);
> --
> 2.7.4
> 
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