perf: Optimize IPID (Avoid the futex of rand() while ensuring that IPID increases monotonically)

common/include/utils.h

@@ -105,7 +105,7 @@ struct udp_hdr
 } __attribute__((__packed__));
 
 void build_udp_header(const char *l3_hdr, int l3_hdr_len, struct udp_hdr *udp_hdr, uint16_t udp_sport, uint16_t udp_dport, int payload_len);
-void build_ip_header(struct ip *ip_hdr, uint8_t next_protocol, const char *src_addr, const char *dst_addr, uint16_t payload_len);
+void build_ip_header(struct ip *ip_hdr, uint8_t next_protocol, uint16_t ipid, const char *src_addr, const char *dst_addr, uint16_t payload_len);
 void build_ether_header(struct ethhdr *eth_hdr, uint16_t next_protocol, const char *src_mac, const char *dst_mac);
 
 /******************************************************************************

common/src/utils.cpp

@@ -196,16 +196,16 @@ void build_udp_header(const char *l3_hdr, int l3_hdr_len, struct udp_hdr *udp_hd
     udp_hdr->uh_sum = CHECKSUM_CARRY(sum);
 }
 
-void build_ip_header(struct ip *ip_hdr, uint8_t next_protocol, const char *src_addr, const char *dst_addr, uint16_t payload_len)
+void build_ip_header(struct ip *ip_hdr, uint8_t next_protocol, uint16_t ipid, const char *src_addr, const char *dst_addr, uint16_t payload_len)
 {
     memset(ip_hdr, 0, sizeof(struct ip));
 
-    ip_hdr->ip_hl = 5;               /* 20 byte header */
+    ip_hdr->ip_hl = 5;            /* 20 byte header */
-    ip_hdr->ip_v = 4;                /* version 4 */
+    ip_hdr->ip_v = 4;             /* version 4 */
-    ip_hdr->ip_tos = 0;              /* IP tos */
+    ip_hdr->ip_tos = 0;           /* IP tos */
-    ip_hdr->ip_id = htons(random()); /* IP ID */
+    ip_hdr->ip_id = htons(ipid);  /* IP ID */
-    ip_hdr->ip_ttl = 80;             /* time to live */
+    ip_hdr->ip_ttl = 80;          /* time to live */
-    ip_hdr->ip_p = next_protocol;    /* transport protocol */
+    ip_hdr->ip_p = next_protocol; /* transport protocol */
     ip_hdr->ip_src.s_addr = inet_addr(src_addr);
     ip_hdr->ip_dst.s_addr = inet_addr(dst_addr);
     ip_hdr->ip_len = htons(sizeof(struct ip) + payload_len); /* total length */

platform/include/sce.h

@@ -34,6 +34,7 @@ struct thread_ctx
 
     int session_table_need_reset;
     int thread_is_runing;
+    uint64_t tx_packets_to_sf;
 };
 
 /******************************************************************************

platform/src/main.cpp

@@ -194,6 +194,7 @@ int main(int argc, char **argv)
         ctx->work_threads[i].ref_enforcer = ctx->enforcer;
         ctx->work_threads[i].ref_sce_ctx = ctx;
         ctx->work_threads[i].session_table_need_reset = 0;
+        ctx->work_threads[i].tx_packets_to_sf = 0;
     }
 
     for (int i = 0; i < ctx->nr_worker_threads; i++)

platform/src/packet_io.cpp

@@ -397,7 +397,8 @@ static struct session_ctx *inject_packet_search_session(struct session_table *ta
 static void vxlan_encapsulate(char *buffer,
                               const char *src_mac_str, const char *dst_mac_str,
                               const char *src_ip_str, const char *dst_ip_str,
-                              int payload_len, int is_e2i, int is_decrypted, int sf_index, uint64_t session_id)
+                              int payload_len, int is_e2i, int is_decrypted, int sf_index,
+                              uint64_t session_id, uint16_t ipid)
 {
     struct ethhdr *eth_hdr = (struct ethhdr *)buffer;
     struct ip *ip_hdr = (struct ip *)((char *)eth_hdr + sizeof(struct ethhdr));
@@ -410,12 +411,13 @@ static void vxlan_encapsulate(char *buffer,
     g_vxlan_set_traffic_type(g_vxlan_hdr, is_decrypted);
 
     build_ether_header(eth_hdr, ETH_P_IP, src_mac_str, dst_mac_str);
-    build_ip_header(ip_hdr, IPPROTO_UDP, src_ip_str, dst_ip_str, sizeof(struct udp_hdr) + sizeof(struct g_vxlan) + payload_len);
+    build_ip_header(ip_hdr, IPPROTO_UDP, ipid, src_ip_str, dst_ip_str, sizeof(struct udp_hdr) + sizeof(struct g_vxlan) + payload_len);
     build_udp_header((const char *)&ip_hdr->ip_src, 8, udp_hdr, session_id % (65535 - 49152) + 49152, 4789, sizeof(struct g_vxlan) + payload_len);
 }
 
 static int send_packet_to_sf(marsio_buff_t *rx_buff, struct metadata *meta, struct selected_sf *sf, struct thread_ctx *thread_ctx)
 {
+    thread_ctx->tx_packets_to_sf++;
     struct packet_io *packet_io = thread_ctx->ref_io;
     int thread_index = thread_ctx->thread_index;
 
@@ -436,7 +438,7 @@ static int send_packet_to_sf(marsio_buff_t *rx_buff, struct metadata *meta, stru
     case PACKAGE_METHOD_VXLAN_G:
         prepend_len = sizeof(struct ethhdr) + sizeof(struct ip) + sizeof(struct udp_hdr) + sizeof(struct g_vxlan);
         buffer = marsio_buff_prepend(rx_buff, prepend_len);
-        vxlan_encapsulate(buffer, src_mac_str, dst_mac_str, src_ip_str, dst_ip_str, payload_len, is_e2i, is_decrypted, sf_index, meta->session_id);
+        vxlan_encapsulate(buffer, src_mac_str, dst_mac_str, src_ip_str, dst_ip_str, payload_len, is_e2i, is_decrypted, sf_index, meta->session_id, thread_ctx->tx_packets_to_sf % 65535);
         break;
     case PACKAGE_METHOD_LAYER2_SWITCH:
         // TODO