From: Zhipeng Gong Date: Wed, 4 Apr 2018 08:43:53 +0800 Subject: drm/i915/gvt: Update time slice more frequently Git-commit: 89babe7cf18e4f93c6ba1e6abfe2e5aa5e4fc66c Patch-mainline: v4.18-rc1 References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166 When there is only one vGPU in GVT-g and it submits workloads continuously, it will not be scheduled out, vgpu_update_timeslice is not called and its sched_in_time is not updated in a long time, which can be several seconds or longer. Once GVT-g pauses to submit workload for this vGPU due to heavy host CPU workload, this vGPU get scheduled out and vgpu_update_timeslice is called, its left_ts will be subtract by a big value from sched_out_time - sched_in_time. When GVT-g is going to submit workload for this vGPU again, it will not be scheduled in until gvt_balance_timeslice reaches stage 0 and reset its left_ts, which introduces several hunderand milliseconds latency. This patch updates time slice in every ms to update sched_in_time timely. v2: revise commit message v3: use more concise expr. (Zhenyu) Signed-off-by: Zhipeng Gong Cc: Zhenyu Wang Cc: Min He Signed-off-by: Zhi Wang Acked-by: Petr Tesarik --- drivers/gpu/drm/i915/gvt/sched_policy.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) --- a/drivers/gpu/drm/i915/gvt/sched_policy.c +++ b/drivers/gpu/drm/i915/gvt/sched_policy.c @@ -53,7 +53,6 @@ struct vgpu_sched_data { bool active; ktime_t sched_in_time; - ktime_t sched_out_time; ktime_t sched_time; ktime_t left_ts; ktime_t allocated_ts; @@ -69,15 +68,19 @@ struct gvt_sched_data { ktime_t expire_time; }; -static void vgpu_update_timeslice(struct intel_vgpu *pre_vgpu) +static void vgpu_update_timeslice(struct intel_vgpu *vgpu, ktime_t cur_time) { ktime_t delta_ts; - struct vgpu_sched_data *vgpu_data = pre_vgpu->sched_data; + struct vgpu_sched_data *vgpu_data; - delta_ts = vgpu_data->sched_out_time - vgpu_data->sched_in_time; + if (!vgpu || vgpu == vgpu->gvt->idle_vgpu) + return; - vgpu_data->sched_time += delta_ts; - vgpu_data->left_ts -= delta_ts; + vgpu_data = vgpu->sched_data; + delta_ts = ktime_sub(cur_time, vgpu_data->sched_in_time); + vgpu_data->sched_time = ktime_add(vgpu_data->sched_time, delta_ts); + vgpu_data->left_ts = ktime_sub(vgpu_data->left_ts, delta_ts); + vgpu_data->sched_in_time = cur_time; } #define GVT_TS_BALANCE_PERIOD_MS 100 @@ -151,11 +154,7 @@ static void try_to_schedule_next_vgpu(st } cur_time = ktime_get(); - if (scheduler->current_vgpu) { - vgpu_data = scheduler->current_vgpu->sched_data; - vgpu_data->sched_out_time = cur_time; - vgpu_update_timeslice(scheduler->current_vgpu); - } + vgpu_update_timeslice(scheduler->current_vgpu, cur_time); vgpu_data = scheduler->next_vgpu->sched_data; vgpu_data->sched_in_time = cur_time; @@ -227,13 +226,13 @@ out: void intel_gvt_schedule(struct intel_gvt *gvt) { struct gvt_sched_data *sched_data = gvt->scheduler.sched_data; + ktime_t cur_time; mutex_lock(&gvt->lock); + cur_time = ktime_get(); if (test_and_clear_bit(INTEL_GVT_REQUEST_SCHED, (void *)&gvt->service_request)) { - ktime_t cur_time = ktime_get(); - if (cur_time >= sched_data->expire_time) { gvt_balance_timeslice(sched_data); sched_data->expire_time = ktime_add_ms( @@ -242,6 +241,7 @@ void intel_gvt_schedule(struct intel_gvt } clear_bit(INTEL_GVT_REQUEST_EVENT_SCHED, (void *)&gvt->service_request); + vgpu_update_timeslice(gvt->scheduler.current_vgpu, cur_time); tbs_sched_func(sched_data); mutex_unlock(&gvt->lock);