[dpdk-dev] [RFC PATCH 4/5] L3fwd-power: enable one-shot rx interrupt and polling/interrupt mode switch

[Danny Zhou <danny.zhou@intel.com>]

Signed-off-by: Danny Zhou <danny.zhou@intel.com>
---
 examples/l3fwd-power/main.c | 127 ++++++++++++++++++++++++++++++++++----------
 1 file changed, 98 insertions(+), 29 deletions(-)

diff --git a/examples/l3fwd-power/main.c b/examples/l3fwd-power/main.c
index f6b55b9..71f1d90 100644
--- a/examples/l3fwd-power/main.c
+++ b/examples/l3fwd-power/main.c
@@ -75,12 +75,13 @@
 #include <rte_string_fns.h>
 #include <rte_timer.h>
 #include <rte_power.h>
+#include <rte_eal.h>
 
 #define RTE_LOGTYPE_L3FWD_POWER RTE_LOGTYPE_USER1
 
 #define MAX_PKT_BURST 32
 
-#define MIN_ZERO_POLL_COUNT 5
+#define MIN_ZERO_POLL_COUNT 10
 
 /* around 100ms at 2 Ghz */
 #define TIMER_RESOLUTION_CYCLES           200000000ULL
@@ -188,6 +189,9 @@ struct lcore_rx_queue {
 #define MAX_TX_QUEUE_PER_PORT RTE_MAX_ETHPORTS
 #define MAX_RX_QUEUE_PER_PORT 128
 
+#define MAX_RX_QUEUE_INTERRUPT_PER_PORT 16
+
+
 #define MAX_LCORE_PARAMS 1024
 struct lcore_params {
 	uint8_t port_id;
@@ -214,7 +218,7 @@ static uint16_t nb_lcore_params = sizeof(lcore_params_array_default) /
 
 static struct rte_eth_conf port_conf = {
 	.rxmode = {
-		.mq_mode	= ETH_MQ_RX_RSS,
+		.mq_mode = ETH_MQ_RX_RSS,
 		.max_rx_pkt_len = ETHER_MAX_LEN,
 		.split_hdr_size = 0,
 		.header_split   = 0, /**< Header Split disabled */
@@ -226,11 +230,15 @@ static struct rte_eth_conf port_conf = {
 	.rx_adv_conf = {
 		.rss_conf = {
 			.rss_key = NULL,
-			.rss_hf = ETH_RSS_IP,
+			.rss_hf = ETH_RSS_UDP,
 		},
 	},
 	.txmode = {
-		.mq_mode = ETH_DCB_NONE,
+		.mq_mode = ETH_MQ_TX_NONE,
+	},
+	.intr_conf = {
+		.lsc = 1,
+		.rxq = 1, /**< rxq interrupt feature enabled */
 	},
 };
 
@@ -402,7 +410,6 @@ power_timer_cb(__attribute__((unused)) struct rte_timer *tim,
 	/* accumulate total execution time in us when callback is invoked */
 	sleep_time_ratio = (float)(stats[lcore_id].sleep_time) /
 					(float)SCALING_PERIOD;
-
 	/**
 	 * check whether need to scale down frequency a step if it sleep a lot.
 	 */
@@ -707,22 +714,20 @@ l3fwd_simple_forward(struct rte_mbuf *m, uint8_t portid,
 
 }
 
-#define SLEEP_GEAR1_THRESHOLD            100
-#define SLEEP_GEAR2_THRESHOLD            1000
+#define MINIMUM_SLEEP_TIME         1
+#define SUSPEND_THRESHOLD          300
 
 static inline uint32_t
 power_idle_heuristic(uint32_t zero_rx_packet_count)
 {
-	/* If zero count is less than 100, use it as the sleep time in us */
-	if (zero_rx_packet_count < SLEEP_GEAR1_THRESHOLD)
-		return zero_rx_packet_count;
-	/* If zero count is less than 1000, sleep time should be 100 us */
-	else if ((zero_rx_packet_count >= SLEEP_GEAR1_THRESHOLD) &&
-			(zero_rx_packet_count < SLEEP_GEAR2_THRESHOLD))
-		return SLEEP_GEAR1_THRESHOLD;
-	/* If zero count is greater than 1000, sleep time should be 1000 us */
-	else if (zero_rx_packet_count >= SLEEP_GEAR2_THRESHOLD)
-		return SLEEP_GEAR2_THRESHOLD;
+	/* If zero count is less than 100,  sleep 1us */
+	if (zero_rx_packet_count < SUSPEND_THRESHOLD)
+		return MINIMUM_SLEEP_TIME;
+	/* If zero count is less than 1000, sleep 100 us which is the minimum latency
+	    switching from C3/C6 to C0
+	*/
+	else
+		return SUSPEND_THRESHOLD;
 
 	return 0;
 }
@@ -762,6 +767,35 @@ power_freq_scaleup_heuristic(unsigned lcore_id,
 	return FREQ_CURRENT;
 }
 
+/**
+ * force polling thread sleep until one-shot rx interrupt triggers
+ * @param port_id
+ *  Port id.
+ * @param queue_id
+ *  Rx queue id.
+ * @return
+ *  0 on success
+ */
+static int
+sleep_until_rx_interrupt(uint8_t port_id, uint8_t queue_id)
+{
+	/* Enable one-shot rx interrupt */
+	rte_eth_dev_rx_queue_intr_enable(port_id, queue_id);
+
+	RTE_LOG(INFO, L3FWD_POWER,
+		"lcore %u sleeps until interrupt on port%d,rxq%d triggers\n",
+		rte_lcore_id(), port_id, queue_id);
+	rte_eal_wait_rx_intr(port_id, queue_id);
+	RTE_LOG(INFO, L3FWD_POWER,
+		"lcore %u is waked up from rx interrupt on port%d,rxq%d\n",
+		rte_lcore_id(), port_id, queue_id);
+
+	/* Disable one-shot rx interrupt */
+	rte_eth_dev_rx_queue_intr_disable(port_id, queue_id);
+
+	return 0;
+}
+
 /* main processing loop */
 static int
 main_loop(__attribute__((unused)) void *dummy)
@@ -775,7 +809,6 @@ main_loop(__attribute__((unused)) void *dummy)
 	struct lcore_conf *qconf;
 	struct lcore_rx_queue *rx_queue;
 	enum freq_scale_hint_t lcore_scaleup_hint;
-
 	uint32_t lcore_rx_idle_count = 0;
 	uint32_t lcore_idle_hint = 0;
 
@@ -835,6 +868,8 @@ main_loop(__attribute__((unused)) void *dummy)
 			prev_tsc_power = cur_tsc_power;
 		}
 
+
+start_rx:
 		/*
 		 * Read packet from RX queues
 		 */
@@ -848,6 +883,7 @@ main_loop(__attribute__((unused)) void *dummy)
 
 			nb_rx = rte_eth_rx_burst(portid, queueid, pkts_burst,
 								MAX_PKT_BURST);
+
 			stats[lcore_id].nb_rx_processed += nb_rx;
 			if (unlikely(nb_rx == 0)) {
 				/**
@@ -928,21 +964,55 @@ main_loop(__attribute__((unused)) void *dummy)
 					lcore_idle_hint = rx_queue->idle_hint;
 			}
 
-			if ( lcore_idle_hint < SLEEP_GEAR1_THRESHOLD)
+			if (lcore_idle_hint < SUSPEND_THRESHOLD)
 				/**
-				 * execute "pause" instruction to avoid context
-				 * switch for short sleep.
- 				 */
+				* execute "pause" instruction to avoid context
+				* switch which generally take hundres of microsecond
+				* for short sleep.
+				*/
 				rte_delay_us(lcore_idle_hint);
-			else
-				/* long sleep force runing thread to suspend */
-				usleep(lcore_idle_hint);
-
+			else {
+				/* suspend untill rx interrupt trigges */
+				sleep_until_rx_interrupt(
+					qconf->rx_queue_list[0].port_id,
+					qconf->rx_queue_list[0].queue_id);
+				/* start receiving packets immediately */
+				goto start_rx;
+			}
 			stats[lcore_id].sleep_time += lcore_idle_hint;
 		}
 	}
 }
 
+/**
+ * It will be called as the callback for specified port after a LSI interrupt
+ * has been fully handled. This callback needs to be implemented carefully as
+ * it will be called in the interrupt host thread which is different from the
+ * application main thread.
+ *
+ * @param port_id
+ *  Port id.
+ * @param type
+ *  event type.
+ * @param param
+ *  Pointer to(address of) the parameters.
+ *
+ * @return
+ *  void.
+ */
+
+/*
+static void
+rx_interrupt_event_callback(uint8_t port_id, enum rte_eth_event_type type, void *param)
+{
+	uint64_t rx_queues = *((uint64_t *)param);
+
+	port_id = port_id + 1;
+	if(type == RTE_ETH_EVENT_INTR_RX)
+		port_id = rx_queues;
+}
+*/
+
 static int
 check_lcore_params(void)
 {
@@ -1270,7 +1340,7 @@ setup_hash(int socketid)
 	char s[64];
 
 	/* create ipv4 hash */
-	snprintf(s, sizeof(s), "ipv4_l3fwd_hash_%d", socketid);
+	rte_snprintf(s, sizeof(s), "ipv4_l3fwd_hash_%d", socketid);
 	ipv4_l3fwd_hash_params.name = s;
 	ipv4_l3fwd_hash_params.socket_id = socketid;
 	ipv4_l3fwd_lookup_struct[socketid] =
@@ -1280,7 +1350,7 @@ setup_hash(int socketid)
 				"socket %d\n", socketid);
 
 	/* create ipv6 hash */
-	snprintf(s, sizeof(s), "ipv6_l3fwd_hash_%d", socketid);
+	rte_snprintf(s, sizeof(s), "ipv6_l3fwd_hash_%d", socketid);
 	ipv6_l3fwd_hash_params.name = s;
 	ipv6_l3fwd_hash_params.socket_id = socketid;
 	ipv6_l3fwd_lookup_struct[socketid] =
@@ -1635,7 +1705,6 @@ main(int argc, char **argv)
 		if (ret < 0)
 			rte_exit(EXIT_FAILURE, "rte_eth_dev_start: err=%d, "
 						"port=%d\n", ret, portid);
-
 		/*
 		 * If enabled, put device in promiscuous mode.
 		 * This allows IO forwarding mode to forward packets
-- 
1.8.1.4