add "idle_sleep" to reduce CPU usage when no pkts incomming.

config.ini

@@ -9,6 +9,10 @@ tso=0
 ## HW vlan strip, default: enabled.
 vlan_strip=1
 
+# sleep when no pkts incomming
+# unit: microseconds
+idle_sleep=100
+
 # enabled port list
 #
 # EBNF grammar:

lib/ff_config.c

@@ -297,7 +297,7 @@ __parse_config_list(uint16_t *arr, int *sz, const char *value) {
         }
     }
     if (nr_ele <= 0) {
-        printf("list %s is empty\n", value);
+        fprintf(stderr, "list %s is empty\n", value);
         return 1;
     }
     sort_uint16_array(arr, nr_ele);
@@ -430,6 +430,8 @@ ini_parse_handler(void* user, const char* section, const char* name,
         pconfig->dpdk.tso = atoi(value);
     } else if (MATCH("dpdk", "vlan_strip")) {
         pconfig->dpdk.vlan_strip = atoi(value);
+    } else if (MATCH("dpdk", "idle_sleep")) {
+        pconfig->dpdk.idle_sleep = atoi(value);
     } else if (MATCH("kni", "enable")) {
         pconfig->kni.enable= atoi(value);
     } else if (MATCH("kni", "method")) {

lib/ff_config.h

@@ -31,8 +31,8 @@
 extern "C" {
 #endif
 
-// dpdk argc, argv, max argc: 4, member of dpdk_config
-#define DPDK_CONFIG_NUM 4
+// dpdk argc, argv, max argc: 16, member of dpdk_config
+#define DPDK_CONFIG_NUM 16
 #define DPDK_CONFIG_MAXLEN 64
 #define DPDK_MAX_LCORE 128
 
@@ -88,12 +88,16 @@ struct ff_config {
         int numa_on;
         int tso;
         int vlan_strip;
+
+        /* sleep x microseconds when no pkts incomming */
+        unsigned idle_sleep;
+
         /* list of proc-lcore */
         uint16_t *proc_lcore;
 
         int nb_ports;
-        uint16_t *portid_list;
         uint16_t max_portid;
+        uint16_t *portid_list;
         // MAP(portid => struct ff_port_cfg*)
         struct ff_port_cfg *port_cfgs;
     } dpdk;

lib/ff_dpdk_if.c

@@ -24,6 +24,7 @@
  *
  */
 #include <assert.h>
+#include <unistd.h>
 
 #include <rte_common.h>
 #include <rte_byteorder.h>
@@ -98,6 +99,8 @@ static int kni_accept;
 
 static int numa_on;
 
+static unsigned idle_sleep;
+
 static struct rte_timer freebsd_clock;
 
 // Mellanox Linux's driver key
@@ -821,6 +824,8 @@ ff_dpdk_init(int argc, char **argv)
 
     numa_on = ff_global_cfg.dpdk.numa_on;
 
+    idle_sleep = ff_global_cfg.dpdk.idle_sleep;
+
     init_lcore_conf();
 
     init_mem_pool();
@@ -1429,7 +1434,7 @@ main_loop(void *arg)
     struct loop_routine *lr = (struct loop_routine *)arg;
 
     struct rte_mbuf *pkts_burst[MAX_PKT_BURST];
-    uint64_t prev_tsc, diff_tsc, cur_tsc, usch_tsc, div_tsc, usr_tsc, sys_tsc, end_tsc;
+    uint64_t prev_tsc, diff_tsc, cur_tsc, usch_tsc, div_tsc, usr_tsc, sys_tsc, end_tsc, idle_sleep_tsc;
     int i, j, nb_rx, idle;
     uint16_t port_id, queue_id;
     struct lcore_conf *qconf;
@@ -1524,10 +1529,18 @@ main_loop(void *arg)
             lr->loop(lr->arg);
         }
 
+        idle_sleep_tsc = rte_rdtsc();
+        if (likely(idle && idle_sleep)) {
+            usleep(idle_sleep);
+            end_tsc = rte_rdtsc();
+        } else {
+            end_tsc = idle_sleep_tsc;
+        }
+
         end_tsc = rte_rdtsc();
 
         if (usch_tsc == cur_tsc) {
-            usr_tsc = end_tsc - div_tsc;
+            usr_tsc = idle_sleep_tsc - div_tsc;
         }
 
         if (!idle) {