RE: [dpdk][PATCH 1/2] sched: enable/disable TC OV at runtime

["Singh, Jasvinder" <jasvinder.singh@intel.com>]

> -----Original Message-----
> From: Marcin Danilewicz <marcinx.danilewicz@intel.com>
> Sent: Thursday, April 7, 2022 3:52 PM
> To: dev@dpdk.org
> Cc: Ajmera, Megha <megha.ajmera@intel.com>
> Subject: [dpdk][PATCH 1/2] sched: enable/disable TC OV at runtime
> 
> From: Megha Ajmera <megha.ajmera@intel.com>
> 
> Added new API to enable or disable TC over subscription for best effort
> traffic class at subport level.
> 
> By default TC OV is disabled for subport.
> 
> Signed-off-by: Megha Ajmera <megha.ajmera@intel.com>
> 
> diff --git a/lib/sched/rte_sched.c b/lib/sched/rte_sched.c index
> ec74bee939..1d05089d00 100644
> --- a/lib/sched/rte_sched.c
> +++ b/lib/sched/rte_sched.c
> @@ -155,6 +155,7 @@ struct rte_sched_subport {
>  	uint64_t tc_credits[RTE_SCHED_TRAFFIC_CLASSES_PER_PIPE];
> 
>  	/* TC oversubscription */
> +	uint8_t is_tc_ov_enabled;
>  	uint64_t tc_ov_wm;
>  	uint64_t tc_ov_wm_min;
>  	uint64_t tc_ov_wm_max;
> @@ -1165,6 +1166,45 @@ rte_sched_cman_config(struct rte_sched_port
> *port,  }  #endif
> 
> +int
> +rte_sched_subport_tc_ov_config(struct rte_sched_port *port,
> +	uint32_t subport_id,
> +	bool tc_ov_enable)
> +{
> +	struct rte_sched_subport *s;
> +	struct rte_sched_subport_profile *profile;
> +
> +	if (port == NULL) {
> +		RTE_LOG(ERR, SCHED,
> +			"%s: Incorrect value for parameter port\n",
> __func__);
> +		return -EINVAL;
> +	}
> +
> +	if (subport_id >= port->n_subports_per_port) {
> +		RTE_LOG(ERR, SCHED,
> +			"%s: Incorrect value for parameter subport id\n",
> __func__);
> +		return  -EINVAL;
> +	}
> +
> +	s = port->subports[subport_id];
> +	s->is_tc_ov_enabled = tc_ov_enable;
> +
> +	if (s->is_tc_ov_enabled) {
> +		/* TC oversubscription */
> +		s->tc_ov_wm_min = port->mtu;
> +		s->tc_ov_period_id = 0;
> +		s->tc_ov = 0;
> +		s->tc_ov_n = 0;
> +		s->tc_ov_rate = 0;
> +
> +		profile = port->subport_profiles + s->profile;
> +		s->tc_ov_wm_max = rte_sched_time_ms_to_bytes(profile-
> >tc_period,
> +				s->pipe_tc_be_rate_max);
> +		s->tc_ov_wm = s->tc_ov_wm_max;
> +	}
> +	return 0;
> +}


This API should be invoked immediately after subport config function because during pipe configuration,  subport tc_ov parameters are updated based on the pipe best effort tc parameters.  With this condition, won't it be good to add tc_ov_enable/disable flag to subport params instead of adding new API? 


> +
>  int
>  rte_sched_subport_config(struct rte_sched_port *port,
>  	uint32_t subport_id,
> @@ -1317,12 +1357,8 @@ rte_sched_subport_config(struct rte_sched_port
> *port,
>  		for (i = 0; i < RTE_SCHED_PORT_N_GRINDERS; i++)
>  			s->grinder_base_bmp_pos[i] =
> RTE_SCHED_PIPE_INVALID;
> 
> -		/* TC oversubscription */
> -		s->tc_ov_wm_min = port->mtu;
> -		s->tc_ov_period_id = 0;
> -		s->tc_ov = 0;
> -		s->tc_ov_n = 0;
> -		s->tc_ov_rate = 0;
> +		/* TC over-subscription is disabled by default */
> +		s->is_tc_ov_enabled = 0;
>  	}
> 
>  	{
> @@ -1342,9 +1378,6 @@ rte_sched_subport_config(struct rte_sched_port
> *port,
>  			else
>  				profile->tc_credits_per_period[i] = 0;
> 
> -		s->tc_ov_wm_max = rte_sched_time_ms_to_bytes(profile-
> >tc_period,
> -							s-
> >pipe_tc_be_rate_max);
> -		s->tc_ov_wm = s->tc_ov_wm_max;
>  		s->profile = subport_profile_id;
> 
>  	}
> @@ -1417,17 +1450,20 @@ rte_sched_pipe_config(struct rte_sched_port
> *port,
>  		double pipe_tc_be_rate =
>  			(double) params-
> >tc_credits_per_period[RTE_SCHED_TRAFFIC_CLASS_BE]
>  			/ (double) params->tc_period;
> -		uint32_t tc_be_ov = s->tc_ov;
> 
> -		/* Unplug pipe from its subport */
> -		s->tc_ov_n -= params->tc_ov_weight;
> -		s->tc_ov_rate -= pipe_tc_be_rate;
> -		s->tc_ov = s->tc_ov_rate > subport_tc_be_rate;
> +		if (s->is_tc_ov_enabled) {
> +			uint32_t tc_be_ov = s->tc_ov;
> 
> -		if (s->tc_ov != tc_be_ov) {
> -			RTE_LOG(DEBUG, SCHED,
> -				"Subport %u Best-effort TC oversubscription
> is OFF (%.4lf >= %.4lf)\n",
> -				subport_id, subport_tc_be_rate, s-
> >tc_ov_rate);
> +			/* Unplug pipe from its subport */
> +			s->tc_ov_n -= params->tc_ov_weight;
> +			s->tc_ov_rate -= pipe_tc_be_rate;
> +			s->tc_ov = s->tc_ov_rate > subport_tc_be_rate;
> +
> +			if (s->tc_ov != tc_be_ov) {
> +				RTE_LOG(DEBUG, SCHED,
> +					"Subport %u Best-effort TC
> oversubscription is OFF (%.4lf >= %.4lf)\n",
> +					subport_id, subport_tc_be_rate, s-
> >tc_ov_rate);
> +			}
>  		}
> 
>  		/* Reset the pipe */
> @@ -1460,19 +1496,22 @@ rte_sched_pipe_config(struct rte_sched_port
> *port,
>  		double pipe_tc_be_rate =
>  			(double) params-
> >tc_credits_per_period[RTE_SCHED_TRAFFIC_CLASS_BE]
>  			/ (double) params->tc_period;
> -		uint32_t tc_be_ov = s->tc_ov;
> 
> -		s->tc_ov_n += params->tc_ov_weight;
> -		s->tc_ov_rate += pipe_tc_be_rate;
> -		s->tc_ov = s->tc_ov_rate > subport_tc_be_rate;
> +		if (s->is_tc_ov_enabled) {
> +			uint32_t tc_be_ov = s->tc_ov;
> 
> -		if (s->tc_ov != tc_be_ov) {
> -			RTE_LOG(DEBUG, SCHED,
> -				"Subport %u Best effort TC oversubscription
> is ON (%.4lf < %.4lf)\n",
> -				subport_id, subport_tc_be_rate, s-
> >tc_ov_rate);
> +			s->tc_ov_n += params->tc_ov_weight;
> +			s->tc_ov_rate += pipe_tc_be_rate;
> +			s->tc_ov = s->tc_ov_rate > subport_tc_be_rate;
> +
> +			if (s->tc_ov != tc_be_ov) {
> +				RTE_LOG(DEBUG, SCHED,
> +					"Subport %u Best effort TC
> oversubscription is ON (%.4lf < %.4lf)\n",
> +					subport_id, subport_tc_be_rate, s-
> >tc_ov_rate);
> +			}
> +			p->tc_ov_period_id = s->tc_ov_period_id;
> +			p->tc_ov_credits = s->tc_ov_wm;
>  		}
> -		p->tc_ov_period_id = s->tc_ov_period_id;
> -		p->tc_ov_credits = s->tc_ov_wm;
>  	}
>