[PATCH v2 8/9] drm/i915/gvt: control the scheduler by timeslice usage

[Ping Gao]

The timeslice usage will determine vGPU whether has chance to
schedule or not at every vGPU switch checkpoint.

Signed-off-by: Ping Gao <ping.a.gao at intel.com>
---
 drivers/gpu/drm/i915/gvt/sched_policy.c | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/sched_policy.c b/drivers/gpu/drm/i915/gvt/sched_policy.c
index 081a512..9d40693 100644
--- a/drivers/gpu/drm/i915/gvt/sched_policy.c
+++ b/drivers/gpu/drm/i915/gvt/sched_policy.c
@@ -194,6 +194,9 @@ static void try_to_schedule_next_vgpu(struct intel_gvt *gvt)
 		wake_up(&scheduler->waitq[i]);
 }
 
+#define vgpu_has_ts_limit(vgpu_data) \
+((vgpu_data)->ts_alloc < GVT_TS_BALANCE_PERIOD_CYC)
+
 static struct intel_vgpu *get_vgpu_timeslice_left(struct list_head *head,
 					struct tbs_sched_data *sched_data)
 {
@@ -210,8 +213,16 @@ static struct intel_vgpu *get_vgpu_timeslice_left(struct list_head *head,
 		if (!vgpu_has_pending_workload(vgpu_data->vgpu))
 			continue;
 
-		vgpu = vgpu_data->vgpu;
-		break;
+		/* Return the vGPU if there is no time slice limitation */
+		if (!vgpu_has_ts_limit(vgpu_data)) {
+			vgpu = vgpu_data->vgpu;
+			break;
+
+		/* Return the vGPU only if it has time slice left */
+		} else if (vgpu_data->ts_usage > 0) {
+			vgpu = vgpu_data->vgpu;
+			break;
+		}
 	}
 
 	return vgpu;
@@ -275,6 +286,9 @@ static struct list_head *get_sched_head(struct tbs_sched_data *sched_data)
 
 static struct intel_vgpu *pickup_next_vgpu(struct tbs_sched_data *sched_data)
 {
+	struct intel_gvt *gvt = sched_data->gvt;
+	struct intel_gvt_workload_scheduler *scheduler = &gvt->scheduler;
+	struct tbs_vgpu_data *cur_vgpu_data;
 	struct tbs_vgpu_data *next_vgpu_data;
 	struct intel_vgpu *next_vgpu;
 	struct list_head *head;
@@ -299,6 +313,15 @@ static struct intel_vgpu *pickup_next_vgpu(struct tbs_sched_data *sched_data)
 	} else {
 		/* Choose the vGPU which has timeslice left */
 		next_vgpu = get_vgpu_timeslice_left(head, sched_data);
+
+		/* Switch to dummy vGPU when all next candidates are
+		 * empty and the current vGPU has timeslice limitation.
+		 */
+		if (!next_vgpu && scheduler->current_vgpu) {
+			cur_vgpu_data = scheduler->current_vgpu->sched_data;
+			if (vgpu_has_ts_limit(cur_vgpu_data))
+				next_vgpu = gvt->dummy_vgpu;
+		}
 	}
 
 	return next_vgpu;
-- 
2.7.4