[PATCH v2 1/2] drm/i915/gvt: Use real time to do timer check

[Zhenyu Wang]

On 2018.04.03 09:24:24 +0800, Zhipeng Gong wrote:
> intel_gvt_schedule check timer through a counter and is supposed
> to wake up to increase the counter every ms.
> In a system with heavy workload, gvt_service_thread can not get
> a chance to run right after wake up and will be delayed several
> milliseconds. As a result, one hundred counter interval means
> several hundred milliseconds in real time.
> 
> This patch use real time instead of counter to do timer check.
> 
> v2: remove static variable. (Zhenyu)
> 
> 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 | 8 ++++++--
>  1 file 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 75b7bc7..a8b544a 100644
> --- a/drivers/gpu/drm/i915/gvt/sched_policy.c
> +++ b/drivers/gpu/drm/i915/gvt/sched_policy.c
> @@ -66,6 +66,7 @@ struct gvt_sched_data {
>  	struct hrtimer timer;
>  	unsigned long period;
>  	struct list_head lru_runq_head;
> +	ktime_t expire_time;
>  };
>  
>  static void vgpu_update_timeslice(struct intel_vgpu *pre_vgpu)
> @@ -226,14 +227,17 @@ 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;
> -	static uint64_t timer_check;
>  
>  	mutex_lock(&gvt->lock);
>  
>  	if (test_and_clear_bit(INTEL_GVT_REQUEST_SCHED,
>  				(void *)&gvt->service_request)) {
> -		if (!(timer_check++ % GVT_TS_BALANCE_PERIOD_MS))
> +		if (ktime_get() >= sched_data->expire_time) {
>  			gvt_balance_timeslice(sched_data);
> +			sched_data->expire_time = ktime_add_ms(
> +				sched_data->expire_time,
> +				GVT_TS_BALANCE_PERIOD_MS);
> +		}
>  	}

Use if ktime_after(ktime_get(), expire_time) instead and should initialize expire_time
or we currently just kick in first schedule?

>  	clear_bit(INTEL_GVT_REQUEST_EVENT_SCHED, (void *)&gvt->service_request);
>  
> -- 
> 2.7.4
> 

-- 
Open Source Technology Center, Intel ltd.

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