[PATCH v1] sched: enable/disable TC OV at runtime

[PATCH v1] sched: enable/disable TC OV at runtime

[Megha Ajmera]

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>
---
 lib/sched/rte_sched.c | 182 +++++++++++++++++++++++++++++++++++-------
 lib/sched/rte_sched.h |  18 +++++
 lib/sched/version.map |   3 +
 3 files changed, 172 insertions(+), 31 deletions(-)

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;
+}
+
 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;
 	}
 
 	return 0;
@@ -2318,6 +2357,45 @@ grinder_credits_update(struct rte_sched_port *port,
 	pipe->tb_credits = RTE_MIN(pipe->tb_credits, params->tb_size);
 	pipe->tb_time += n_periods * params->tb_period;
 
+	/* Subport TCs */
+	if (unlikely(port->time >= subport->tc_time)) {
+		for (i = 0; i < RTE_SCHED_TRAFFIC_CLASSES_PER_PIPE; i++)
+			subport->tc_credits[i] = sp->tc_credits_per_period[i];
+
+		subport->tc_time = port->time + sp->tc_period;
+	}
+
+	/* Pipe TCs */
+	if (unlikely(port->time >= pipe->tc_time)) {
+		for (i = 0; i < RTE_SCHED_TRAFFIC_CLASSES_PER_PIPE; i++)
+			pipe->tc_credits[i] = params->tc_credits_per_period[i];
+		pipe->tc_time = port->time + params->tc_period;
+	}
+}
+
+static inline void
+grinder_credits_update_with_tc_ov(struct rte_sched_port *port,
+	struct rte_sched_subport *subport, uint32_t pos)
+{
+	struct rte_sched_grinder *grinder = subport->grinder + pos;
+	struct rte_sched_pipe *pipe = grinder->pipe;
+	struct rte_sched_pipe_profile *params = grinder->pipe_params;
+	struct rte_sched_subport_profile *sp = grinder->subport_params;
+	uint64_t n_periods;
+	uint32_t i;
+
+	/* Subport TB */
+	n_periods = (port->time - subport->tb_time) / sp->tb_period;
+	subport->tb_credits += n_periods * sp->tb_credits_per_period;
+	subport->tb_credits = RTE_MIN(subport->tb_credits, sp->tb_size);
+	subport->tb_time += n_periods * sp->tb_period;
+
+	/* Pipe TB */
+	n_periods = (port->time - pipe->tb_time) / params->tb_period;
+	pipe->tb_credits += n_periods * params->tb_credits_per_period;
+	pipe->tb_credits = RTE_MIN(pipe->tb_credits, params->tb_size);
+	pipe->tb_time += n_periods * params->tb_period;
+
 	/* Subport TCs */
 	if (unlikely(port->time >= subport->tc_time)) {
 		subport->tc_ov_wm =
@@ -2348,6 +2426,39 @@ grinder_credits_update(struct rte_sched_port *port,
 static inline int
 grinder_credits_check(struct rte_sched_port *port,
 	struct rte_sched_subport *subport, uint32_t pos)
+{
+	struct rte_sched_grinder *grinder = subport->grinder + pos;
+	struct rte_sched_pipe *pipe = grinder->pipe;
+	struct rte_mbuf *pkt = grinder->pkt;
+	uint32_t tc_index = grinder->tc_index;
+	uint64_t pkt_len = pkt->pkt_len + port->frame_overhead;
+	uint64_t subport_tb_credits = subport->tb_credits;
+	uint64_t subport_tc_credits = subport->tc_credits[tc_index];
+	uint64_t pipe_tb_credits = pipe->tb_credits;
+	uint64_t pipe_tc_credits = pipe->tc_credits[tc_index];
+	int enough_credits;
+
+	/* Check pipe and subport credits */
+	enough_credits = (pkt_len <= subport_tb_credits) &&
+		(pkt_len <= subport_tc_credits) &&
+		(pkt_len <= pipe_tb_credits) &&
+		(pkt_len <= pipe_tc_credits);
+
+	if (!enough_credits)
+		return 0;
+
+	/* Update pipe and subport credits */
+	subport->tb_credits -= pkt_len;
+	subport->tc_credits[tc_index] -= pkt_len;
+	pipe->tb_credits -= pkt_len;
+	pipe->tc_credits[tc_index] -= pkt_len;
+
+	return 1;
+}
+
+static inline int
+grinder_credits_check_with_tc_ov(struct rte_sched_port *port,
+	struct rte_sched_subport *subport, uint32_t pos)
 {
 	struct rte_sched_grinder *grinder = subport->grinder + pos;
 	struct rte_sched_pipe *pipe = grinder->pipe;
@@ -2403,8 +2514,13 @@ grinder_schedule(struct rte_sched_port *port,
 	uint32_t pkt_len = pkt->pkt_len + port->frame_overhead;
 	uint32_t be_tc_active;
 
-	if (!grinder_credits_check(port, subport, pos))
-		return 0;
+	if (unlikely(subport->is_tc_ov_enabled)) {
+		if (!grinder_credits_check_with_tc_ov(port, subport, pos))
+			return 0;
+	} else {
+		if (!grinder_credits_check(port, subport, pos))
+			return 0;
+	}
 
 	/* Advance port time */
 	port->time += pkt_len;
@@ -2770,7 +2886,11 @@ grinder_handle(struct rte_sched_port *port,
 						subport->profile;
 
 		grinder_prefetch_tc_queue_arrays(subport, pos);
-		grinder_credits_update(port, subport, pos);
+
+		if (unlikely(subport->is_tc_ov_enabled))
+			grinder_credits_update_with_tc_ov(port, subport, pos);
+		else
+			grinder_credits_update(port, subport, pos);
 
 		grinder->state = e_GRINDER_PREFETCH_MBUF;
 		return 0;
diff --git a/lib/sched/rte_sched.h b/lib/sched/rte_sched.h
index 5ece64e527..94febe1d94 100644
--- a/lib/sched/rte_sched.h
+++ b/lib/sched/rte_sched.h
@@ -579,6 +579,24 @@ rte_sched_port_enqueue(struct rte_sched_port *port, struct rte_mbuf **pkts, uint
 int
 rte_sched_port_dequeue(struct rte_sched_port *port, struct rte_mbuf **pkts, uint32_t n_pkts);
 
+/**
+ * Hierarchical scheduler subport TC OV enable/disable config.
+ * Note that this function is safe to use at runtime
+ * to enable/disable TC OV for subport.
+ *
+ * @param port
+ *   Handle to port scheduler instance
+ * @param subport_id
+ *   Subport ID
+ * @param tc_ov_enable
+ *  Boolean flag to enable/disable TC OV
+ * @return
+ *   0 upon success, error code otherwise
+ */
+__rte_experimental
+int
+rte_sched_subport_tc_ov_config(struct rte_sched_port *port, uint32_t subport_id, bool tc_ov_enable);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/sched/version.map b/lib/sched/version.map
index d22c07fc9f..c6e994d8df 100644
--- a/lib/sched/version.map
+++ b/lib/sched/version.map
@@ -34,4 +34,7 @@ EXPERIMENTAL {
 	# added in 21.11
 	rte_pie_rt_data_init;
 	rte_pie_config_init;
+
+	# added in 22.03
+	rte_sched_subport_tc_ov_config;
 };
-- 
2.25.1

Re: [PATCH v1] sched: enable/disable TC OV at runtime

[Stephen Hemminger]

On Thu, 10 Mar 2022 19:54:26 +0000
Megha Ajmera <megha.ajmera@intel.com> wrote:

> 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;

Putting the field there creates a hole in the structure.
Put it after tc_ov and fill an existing hole.

This is pahole of current code, looks like this struct could
use some work to be better packed and aligned.

struct rte_sched_port {
	uint32_t                   n_subports_per_port;  /*     0     4 */
	uint32_t                   n_pipes_per_subport;  /*     4     4 */
	uint32_t                   n_pipes_per_subport_log2; /*     8     4 */
	uint16_t                   pipe_queue[13];       /*    12    26 */
	uint8_t                    pipe_tc[16];          /*    38    16 */
	uint8_t                    tc_queue[16];         /*    54    16 */

	/* XXX 2 bytes hole, try to pack */

	/* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */
	uint32_t                   n_subport_profiles;   /*    72     4 */
	uint32_t                   n_max_subport_profiles; /*    76     4 */
	uint64_t                   rate;                 /*    80     8 */
	uint32_t                   mtu;                  /*    88     4 */
	uint32_t                   frame_overhead;       /*    92     4 */
	int                        socket;               /*    96     4 */

	/* XXX 4 bytes hole, try to pack */

	uint64_t                   time_cpu_cycles;      /*   104     8 */
	uint64_t                   time_cpu_bytes;       /*   112     8 */
	uint64_t                   time;                 /*   120     8 */
	/* --- cacheline 2 boundary (128 bytes) --- */
	struct rte_reciprocal      inv_cycles_per_byte;  /*   128     8 */

	/* XXX last struct has 2 bytes of padding */

	uint64_t                   cycles_per_byte;      /*   136     8 */
	struct rte_mbuf * *        pkts_out;             /*   144     8 */
	uint32_t                   n_pkts_out;           /*   152     4 */
	uint32_t                   subport_id;           /*   156     4 */
	struct rte_sched_subport_profile * subport_profiles; /*   160     8 */

	/* XXX 24 bytes hole, try to pack */

	/* --- cacheline 3 boundary (192 bytes) --- */
	struct rte_sched_subport * subports[] __attribute__((__aligned__(64))); /*   192     0 */

	/* size: 192, cachelines: 3, members: 22 */
	/* sum members: 162, holes: 3, sum holes: 30 */
	/* paddings: 1, sum paddings: 2 */
	/* forced alignments: 1, forced holes: 1, sum forced holes: 24 */
} __attribute__((__aligned__(64)));

RE: [PATCH v1] sched: enable/disable TC OV at runtime

[Ajmera, Megha]

> 
> > 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;
> 
> Putting the field there creates a hole in the structure.
> Put it after tc_ov and fill an existing hole.
> 
> This is pahole of current code, looks like this struct could use some work to be
> better packed and aligned.
>

Thanks Stephen for pointing this out. I agree there is some work needed to pack this structure better.
Can we take this up in a separate patch in later release as it requires more performance test runs to see the impact ?
 

Re: [PATCH v1] sched: enable/disable TC OV at runtime

[Stephen Hemminger]

On Fri, 11 Mar 2022 06:24:35 +0000
"Ajmera, Megha" <megha.ajmera@intel.com> wrote:

> >   
> > > 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;  
> > 
> > Putting the field there creates a hole in the structure.
> > Put it after tc_ov and fill an existing hole.
> > 
> > This is pahole of current code, looks like this struct could use some work to be
> > better packed and aligned.
> >  
> 
> Thanks Stephen for pointing this out. I agree there is some work needed to pack this structure better.
> Can we take this up in a separate patch in later release as it requires more performance test runs to see the impact ?
>  

Please add new field in existing hole