net: Add statistics how long packets have spent in RX path

Calculate how long on average net_pkt has spent on its way from
network device driver to the application. The data is only
calculated for UDP and TCP network packets.

Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>

include/net/net_pkt.h

@@ -97,9 +97,10 @@ struct net_pkt {
 	struct net_if *orig_iface; /* Original network interface */
 #endif
 
-#if defined(CONFIG_NET_PKT_TIMESTAMP) || defined(CONFIG_NET_PKT_TXTIME)
+#if defined(CONFIG_NET_PKT_TIMESTAMP) || defined(CONFIG_NET_PKT_TXTIME) || \
+					defined(CONFIG_NET_PKT_RXTIME_STATS)
 	union {
-#if defined(CONFIG_NET_PKT_TIMESTAMP)
+#if defined(CONFIG_NET_PKT_TIMESTAMP) || defined(CONFIG_NET_PKT_RXTIME_STATS)
 		/** Timestamp if available. */
 		struct net_ptp_time timestamp;
 #endif /* CONFIG_NET_PKT_TIMESTAMP */

include/net/net_stats.h

@@ -210,6 +210,14 @@ struct net_stats_tx_time {
 	net_stats_t time_count;
 };
 
+/**
+ * @brief Network packet receive times for calculating average RX time
+ */
+struct net_stats_rx_time {
+	u64_t sum;
+	net_stats_t count;
+};
+
 /**
  * @brief Traffic class statistics
  */
@@ -222,6 +230,7 @@ struct net_stats_tc {
 	} sent[NET_TC_TX_COUNT];
 
 	struct {
+		struct net_stats_rx_time rx_time;
 		net_stats_t pkts;
 		net_stats_t bytes;
 		u8_t priority;
@@ -288,6 +297,11 @@ struct net_stats {
 	/** Network packet TX time statistics */
 	struct net_stats_tx_time tx_time;
 #endif
+
+#if defined(CONFIG_NET_PKT_RXTIME_STATS)
+	/** Network packet RX time statistics */
+	struct net_stats_rx_time rx_time;
+#endif
 };
 
 /**

subsys/net/ip/Kconfig

@@ -189,13 +189,21 @@ config NET_TC_MAPPING_SR_CLASS_B_ONLY
 endchoice
 
 config NET_TX_DEFAULT_PRIORITY
-	int "Default network packet priority if none have been set"
+	int "Default network TX packet priority if none have been set"
 	default 1
 	range 0 7
 	help
 	  What is the default network packet priority if user has not specified
 	  one. The value 0 means lowest priority and 7 is the highest.
 
+config NET_RX_DEFAULT_PRIORITY
+	int "Default network RX packet priority if none have been set"
+	default 0
+	range 0 7
+	help
+	  What is the default network RX packet priority if user has not set
+	  one. The value 0 means lowest priority and 7 is the highest.
+
 config NET_IP_ADDR_CHECK
 	bool "Check IP address validity before sending IP packet"
 	default y
@@ -640,6 +648,19 @@ config NET_PKT_TXTIME
 	  when the application wants to set the exact time when the network
 	  packet should be sent.
 
+config NET_PKT_RXTIME_STATS
+	bool "Enable network packet RX time statistics"
+	select NET_PKT_TIMESTAMP
+	select NET_STATISTICS
+	depends on (NET_UDP || NET_TCP)
+	help
+	  Enable network packet RX time statistics support. This is used to
+	  calculate how long on average it takes for a packet to travel from
+	  device driver to just before it is given to application. The RX
+	  timing information can then be seen in network interface statistics
+	  in net-shell.
+	  The RX statistics are only calculated for UDP and TCP packets.
+
 config NET_PROMISCUOUS_MODE
 	bool "Enable promiscuous mode support [EXPERIMENTAL]"
 	select NET_MGMT

subsys/net/ip/net_pkt.c

@@ -1187,7 +1187,26 @@ static struct net_pkt *pkt_alloc(struct k_mem_slab *slab, s32_t timeout)
 		net_pkt_set_ipv6_next_hdr(pkt, 255);
 	}
 
-	net_pkt_set_priority(pkt, CONFIG_NET_TX_DEFAULT_PRIORITY);
+	if (&tx_pkts == slab) {
+		net_pkt_set_priority(pkt, CONFIG_NET_TX_DEFAULT_PRIORITY);
+	} else if (&rx_pkts == slab) {
+		net_pkt_set_priority(pkt, CONFIG_NET_RX_DEFAULT_PRIORITY);
+	}
+
+	if (IS_ENABLED(CONFIG_NET_PKT_RXTIME_STATS)) {
+		struct net_ptp_time tp = {
+			/* Use the nanosecond field to temporarily
+			 * store the cycle count as it is a 32-bit
+			 * variable. The net_pkt timestamp field is used
+			 * to calculate how long it takes the packet to travel
+			 * from network device driver to the application.
+			 */
+			.nanosecond = k_cycle_get_32(),
+		};
+
+		net_pkt_set_timestamp(pkt, &tp);
+	}
+
 	net_pkt_set_vlan_tag(pkt, NET_VLAN_TAG_UNSPEC);
 
 #if NET_LOG_LEVEL >= LOG_LEVEL_DBG

subsys/net/ip/net_stats.h

@@ -340,6 +340,21 @@ static inline void net_stats_update_tx_time(struct net_if *iface,
 }
 #endif /* CONFIG_NET_CONTEXT_TIMESTAMP && STATISTICS */
 
+#if defined(CONFIG_NET_PKT_RXTIME_STATS) && defined(CONFIG_NET_STATISTICS)
+static inline void net_stats_update_rx_time(struct net_if *iface,
+					    u32_t start_time,
+					    u32_t end_time)
+{
+	u32_t diff = end_time - start_time;
+
+	UPDATE_STAT(iface, stats.rx_time.sum +=
+		    SYS_CLOCK_HW_CYCLES_TO_NS64(diff) / NSEC_PER_USEC);
+	UPDATE_STAT(iface, stats.rx_time.count += 1);
+}
+#else
+#define net_stats_update_rx_time(iface, start_time, end_time)
+#endif /* CONFIG_NET_CONTEXT_TIMESTAMP && STATISTICS */
+
 #if (NET_TC_COUNT > 1) && defined(CONFIG_NET_STATISTICS) \
 	&& defined(CONFIG_NET_NATIVE)
 static inline void net_stats_update_tc_sent_pkt(struct net_if *iface, u8_t tc)
@@ -387,6 +402,25 @@ static inline void net_stats_update_tc_tx_time(struct net_if *iface,
 }
 #endif /* CONFIG_NET_CONTEXT_TIMESTAMP && CONFIG_NET_STATISTICS */
 
+#if defined(CONFIG_NET_PKT_RXTIME_STATS) && defined(CONFIG_NET_STATISTICS) \
+	&& defined(CONFIG_NET_NATIVE)
+static inline void net_stats_update_tc_rx_time(struct net_if *iface,
+					       u8_t tc,
+					       u32_t start_time,
+					       u32_t end_time)
+{
+	u32_t diff = end_time - start_time;
+
+	UPDATE_STAT(iface, stats.tc.recv[tc].rx_time.sum +=
+		    SYS_CLOCK_HW_CYCLES_TO_NS64(diff) / NSEC_PER_USEC);
+	UPDATE_STAT(iface, stats.tc.recv[tc].rx_time.count += 1);
+
+	net_stats_update_rx_time(iface, start_time, end_time);
+}
+#else
+#define net_stats_update_tc_rx_time(iface, tc, start_time, end_time)
+#endif /* NET_PKT_RXTIME_STATS && NET_STATISTICS */
+
 static inline void net_stats_update_tc_recv_pkt(struct net_if *iface, u8_t tc)
 {
 	UPDATE_STAT(iface, stats.tc.recv[tc].pkts++);
@@ -434,6 +468,21 @@ static inline void net_stats_update_tc_tx_time(struct net_if *iface,
 	ARG_UNUSED(end_time);
 }
 #endif /* CONFIG_NET_CONTEXT_TIMESTAMP && CONFIG_NET_STATISTICS */
+
+#if defined(CONFIG_NET_PKT_RXTIME_STATS) && defined(CONFIG_NET_STATISTICS) \
+	&& defined(CONFIG_NET_NATIVE)
+static inline void net_stats_update_tc_rx_time(struct net_if *iface,
+					       u8_t pkt_priority,
+					       u32_t start_time,
+					       u32_t end_time)
+{
+	ARG_UNUSED(pkt_priority);
+
+	net_stats_update_rx_time(iface, start_time, end_time);
+}
+#else
+#define net_stats_update_tc_rx_time(iface, priority, start_time, end_time)
+#endif /* NET_PKT_RXTIME_STATS && NET_STATISTICS */
 #endif /* NET_TC_COUNT > 1 */
 
 #if defined(CONFIG_NET_STATISTICS_PERIODIC_OUTPUT) \

subsys/net/lib/sockets/sockets.c

@@ -19,6 +19,7 @@ LOG_MODULE_REGISTER(net_sock, CONFIG_NET_SOCKETS_LOG_LEVEL);
 #include <sys/fdtable.h>
 #include <sys/math_extras.h>
 #include <net/socks.h>
+#include "../../ip/net_stats.h"
 
 #include "sockets_internal.h"
 
@@ -765,6 +766,11 @@ static inline ssize_t zsock_recv_dgram(struct net_context *ctx,
 		return -1;
 	}
 
+	net_stats_update_tc_rx_time(net_pkt_iface(pkt),
+				    net_pkt_priority(pkt),
+				    net_pkt_timestamp(pkt)->nanosecond,
+				    k_cycle_get_32());
+
 	if (!(flags & ZSOCK_MSG_PEEK)) {
 		net_pkt_unref(pkt);
 	} else {
@@ -846,6 +852,12 @@ static inline ssize_t zsock_recv_stream(struct net_context *ctx,
 					sock_set_eof(ctx);
 				}
 
+				net_stats_update_tc_rx_time(
+					net_pkt_iface(pkt),
+					net_pkt_priority(pkt),
+					net_pkt_timestamp(pkt)->nanosecond,
+					k_cycle_get_32());
+
 				net_pkt_unref(pkt);
 			}
 		} else {