drm/i915/gvt: avoid unnecessary vgpu switch

It's no need to switch vgpu if next vgpu is the same with current
vgpu, otherwise it will make performance drop in some case.

v2: correct the comments.

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

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/gvt/sched_policy.c b/drivers/gpu/drm/i915/gvt/sched_policy.c
index 34b9acdf3479..6ac77f8cc405 100644
--- a/drivers/gpu/drm/i915/gvt/sched_policy.c
+++ b/drivers/gpu/drm/i915/gvt/sched_policy.c
@@ -53,9 +53,13 @@ static void try_to_schedule_next_vgpu(struct intel_gvt *gvt)
         enum intel_engine_id i;
         struct intel_engine_cs *engine;
 
-        /* no target to schedule */
-        if (!scheduler->next_vgpu)
+        /* no need to schedule if next_vgpu is the same with current_vgpu,
+         * let scheduler chose next_vgpu again by setting it to NULL.
+         */
+        if (scheduler->next_vgpu == scheduler->current_vgpu) {
+                scheduler->next_vgpu = NULL;
                 return;
+        }
 
         gvt_dbg_sched("try to schedule next vgpu %d\n",
                         scheduler->next_vgpu->id);