[PATCH v2 2/2] drm/i915/gvt: Update time slice more frequently
Zhenyu Wang
zhenyuw at linux.intel.com
Tue Apr 3 06:35:31 UTC 2018
On 2018.04.03 09:24:25 +0800, Zhipeng Gong wrote:
> 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
>
> Signed-off-by: Zhipeng Gong <zhipeng.gong at intel.com>
> Cc: Zhenyu Wang <zhenyuw at linux.intel.com>
> Cc: Min He <min.he at intel.com>
> ---
> drivers/gpu/drm/i915/gvt/sched_policy.c | 26 ++++++++++++++------------
> 1 file changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gvt/sched_policy.c b/drivers/gpu/drm/i915/gvt/sched_policy.c
> index a8b544a..0169e3b 100644
> --- 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 == NULL || vgpu == vgpu->gvt->idle_vgpu)
> + return;
Use if (!vgpu || ...)
>
> - 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(struct intel_gvt *gvt)
> }
>
> 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;
Can simply put ktime_get() into vgpu_update_timeslice(), and above lines can be removed as well.
>
> @@ -227,12 +226,14 @@ static void tbs_sched_func(struct gvt_sched_data *sched_data)
> 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)) {
> - if (ktime_get() >= sched_data->expire_time) {
> + if (cur_time >= sched_data->expire_time) {
> gvt_balance_timeslice(sched_data);
> sched_data->expire_time = ktime_add_ms(
> sched_data->expire_time,
> @@ -241,6 +242,7 @@ void intel_gvt_schedule(struct intel_gvt *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);
> --
> 2.7.4
>
> _______________________________________________
> intel-gvt-dev mailing list
> intel-gvt-dev at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gvt-dev
--
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