drm/i915/gvt: use hrtimer replace delayed_work in scheduler

Currently the scheduler is triggered by delayed_work, which doesn't
provide precision at microsecond level. Move to hrtimer instead for
more accurate control.

Signed-off-by: Ping Gao <ping.a.gao@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/gvt/gvt.c b/drivers/gpu/drm/i915/gvt/gvt.c
index b84b7ca..894735c 100644 (file)
--- a/drivers/gpu/drm/i915/gvt/gvt.c
+++ b/drivers/gpu/drm/i915/gvt/gvt.c
@@ -144,6 +144,11 @@ static int gvt_service_thread(void *data)
                        intel_gvt_emulate_vblank(gvt);
                        mutex_unlock(&gvt->lock);
                }
+
+               if (test_and_clear_bit(INTEL_GVT_REQUEST_SCHED,
+                                       (void *)&gvt->service_request)) {
+                       intel_gvt_schedule(gvt);
+               }
        }
 
        return 0;

diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h
index 6dfc48b..7455214 100644 (file)
--- a/drivers/gpu/drm/i915/gvt/gvt.h
+++ b/drivers/gpu/drm/i915/gvt/gvt.h
@@ -249,6 +249,7 @@ static inline struct intel_gvt *to_gvt(struct drm_i915_private *i915)
 
 enum {
        INTEL_GVT_REQUEST_EMULATE_VBLANK = 0,
+       INTEL_GVT_REQUEST_SCHED = 1,
 };
 
 static inline void intel_gvt_request_service(struct intel_gvt *gvt,

diff --git a/drivers/gpu/drm/i915/gvt/sched_policy.c b/drivers/gpu/drm/i915/gvt/sched_policy.c
index 34b9acd..c8ade8f 100644 (file)
--- a/drivers/gpu/drm/i915/gvt/sched_policy.c
+++ b/drivers/gpu/drm/i915/gvt/sched_policy.c
@@ -96,17 +96,16 @@ struct tbs_vgpu_data {
 
 struct tbs_sched_data {
        struct intel_gvt *gvt;
-       struct delayed_work work;
+       struct hrtimer timer;
        unsigned long period;
        struct list_head runq_head;
 };
 
-#define GVT_DEFAULT_TIME_SLICE (msecs_to_jiffies(1))
+/* in nanosecond */
+#define GVT_DEFAULT_TIME_SLICE 1000000
 
-static void tbs_sched_func(struct work_struct *work)
+static void tbs_sched_func(struct tbs_sched_data *sched_data)
 {
-       struct tbs_sched_data *sched_data = container_of(work,
-                       struct tbs_sched_data, work.work);
        struct tbs_vgpu_data *vgpu_data;
 
        struct intel_gvt *gvt = sched_data->gvt;
@@ -115,8 +114,6 @@ static void tbs_sched_func(struct work_struct *work)
        struct intel_vgpu *vgpu = NULL;
        struct list_head *pos, *head;
 
-       mutex_lock(&gvt->lock);
-
        /* no vgpu or has already had a target */
        if (list_empty(&sched_data->runq_head) || scheduler->next_vgpu)
                goto out;
@@ -151,17 +148,30 @@ out:
                                scheduler->next_vgpu->id);
                try_to_schedule_next_vgpu(gvt);
        }
+}
 
-       /*
-        * still have vgpu on runq
-        * or last schedule haven't finished due to running workload
-        */
-       if (!list_empty(&sched_data->runq_head) || scheduler->next_vgpu)
-               schedule_delayed_work(&sched_data->work, sched_data->period);
+void intel_gvt_schedule(struct intel_gvt *gvt)
+{
+       struct tbs_sched_data *sched_data = gvt->scheduler.sched_data;
 
+       mutex_lock(&gvt->lock);
+       tbs_sched_func(sched_data);
        mutex_unlock(&gvt->lock);
 }
 
+static enum hrtimer_restart tbs_timer_fn(struct hrtimer *timer_data)
+{
+       struct tbs_sched_data *data;
+
+       data = container_of(timer_data, struct tbs_sched_data, timer);
+
+       intel_gvt_request_service(data->gvt, INTEL_GVT_REQUEST_SCHED);
+
+       hrtimer_add_expires_ns(&data->timer, data->period);
+
+       return HRTIMER_RESTART;
+}
+
 static int tbs_sched_init(struct intel_gvt *gvt)
 {
        struct intel_gvt_workload_scheduler *scheduler =
@@ -174,11 +184,13 @@ static int tbs_sched_init(struct intel_gvt *gvt)
                return -ENOMEM;
 
        INIT_LIST_HEAD(&data->runq_head);
-       INIT_DELAYED_WORK(&data->work, tbs_sched_func);
+       hrtimer_init(&data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+       data->timer.function = tbs_timer_fn;
        data->period = GVT_DEFAULT_TIME_SLICE;
        data->gvt = gvt;
 
        scheduler->sched_data = data;
+
        return 0;
 }
 
@@ -188,7 +200,8 @@ static void tbs_sched_clean(struct intel_gvt *gvt)
                &gvt->scheduler;
        struct tbs_sched_data *data = scheduler->sched_data;
 
-       cancel_delayed_work(&data->work);
+       hrtimer_cancel(&data->timer);
+
        kfree(data);
        scheduler->sched_data = NULL;
 }
@@ -205,6 +218,7 @@ static int tbs_sched_init_vgpu(struct intel_vgpu *vgpu)
        INIT_LIST_HEAD(&data->list);
 
        vgpu->sched_data = data;
+
        return 0;
 }
 
@@ -223,7 +237,10 @@ static void tbs_sched_start_schedule(struct intel_vgpu *vgpu)
                return;
 
        list_add_tail(&vgpu_data->list, &sched_data->runq_head);
-       schedule_delayed_work(&sched_data->work, 0);
+
+       if (!hrtimer_active(&sched_data->timer))
+               hrtimer_start(&sched_data->timer, ktime_add_ns(ktime_get(),
+                       sched_data->period), HRTIMER_MODE_ABS);
 }
 
 static void tbs_sched_stop_schedule(struct intel_vgpu *vgpu)

diff --git a/drivers/gpu/drm/i915/gvt/sched_policy.h b/drivers/gpu/drm/i915/gvt/sched_policy.h
index bb8b909..ba00a5f 100644 (file)
--- a/drivers/gpu/drm/i915/gvt/sched_policy.h
+++ b/drivers/gpu/drm/i915/gvt/sched_policy.h
@@ -43,6 +43,8 @@ struct intel_gvt_sched_policy_ops {
        void (*stop_schedule)(struct intel_vgpu *vgpu);
 };
 
+void intel_gvt_schedule(struct intel_gvt *gvt);
+
 int intel_gvt_init_sched_policy(struct intel_gvt *gvt);
 
 void intel_gvt_clean_sched_policy(struct intel_gvt *gvt);