netsim_common,tap,wire: support for sync ethernet

net_tap/net_tap.c

@@ -75,7 +75,7 @@ static void d2n_send(volatile struct cosim_eth_proto_d2n_send *s)
 
 static void poll_d2n(void)
 {
-    volatile union cosim_eth_proto_d2n *msg = netsim_d2n_poll(&nsif);
+    volatile union cosim_eth_proto_d2n *msg = netsim_d2n_poll(&nsif, 0);
     uint8_t type;
 
     /* message not ready */
@@ -102,7 +102,7 @@ static void *rx_handler(void *arg)
     ssize_t len;
 
     while (1) {
-        msg = netsim_n2d_alloc(&nsif);
+        msg = netsim_n2d_alloc(&nsif, 0, 0);
         if (msg == NULL) {
             fprintf(stderr, "coudl not allocate message for rx\n");
             abort();

net_wire/net_wire.c

@@ -34,9 +34,13 @@
 
 #include <netsim.h>
 
-static void move_pkt(struct netsim_interface *from, struct netsim_interface *to)
+#define SYNC_PERIOD (500 * 1000ULL) // 100ns
+#define ETH_LATENCY (1 * 1000 * 1000ULL) // 1us
+
+static void move_pkt(uint64_t cur_ts, struct netsim_interface *from,
+        struct netsim_interface *to)
 {
-    volatile union cosim_eth_proto_d2n *msg_from = netsim_d2n_poll(from);
+    volatile union cosim_eth_proto_d2n *msg_from = netsim_d2n_poll(from, cur_ts);
     volatile union cosim_eth_proto_n2d *msg_to;
     volatile struct cosim_eth_proto_d2n_send *tx;
     volatile struct cosim_eth_proto_n2d_recv *rx;
@@ -49,7 +53,7 @@ static void move_pkt(struct netsim_interface *from, struct netsim_interface *to)
     if (type == COSIM_ETH_PROTO_D2N_MSG_SEND) {
         tx = &msg_from->send;
 
-        msg_to = netsim_n2d_alloc(to);
+        msg_to = netsim_n2d_alloc(to, cur_ts, ETH_LATENCY);
         if (msg_to != NULL) {
             rx = &msg_to->recv;
             rx->len = tx->len;
@@ -73,25 +77,47 @@ static void move_pkt(struct netsim_interface *from, struct netsim_interface *to)
 int main(int argc, char *argv[])
 {
     struct netsim_interface nsif_a, nsif_b;
-    int sync;
+    uint64_t cur_ts = 0, ts_a, ts_b;
+    int sync_a, sync_b;
 
     if (argc != 3) {
         fprintf(stderr, "Usage: net_tap SOCKET-A SOCKET-B\n");
         return EXIT_FAILURE;
     }
 
-    sync = 0;
-    if (netsim_init(&nsif_a, argv[1], &sync) != 0) {
+    sync_a = sync_b = 1;
+    if (netsim_init(&nsif_a, argv[1], &sync_a) != 0) {
         return -1;
     }
-    if (netsim_init(&nsif_b, argv[2], &sync) != 0) {
+    if (netsim_init(&nsif_b, argv[2], &sync_b) != 0) {
         return -1;
     }
 
     printf("start polling\n");
     while (1) {
-        move_pkt(&nsif_a, &nsif_b);
-        move_pkt(&nsif_b, &nsif_a);
+        if (netsim_n2d_sync(&nsif_a, cur_ts, ETH_LATENCY, SYNC_PERIOD) != 0) {
+            fprintf(stderr, "netsim_n2d_sync(nsif_a) failed\n");
+            abort();
+        }
+        if (netsim_n2d_sync(&nsif_b, cur_ts, ETH_LATENCY, SYNC_PERIOD) != 0) {
+            fprintf(stderr, "netsim_n2d_sync(nsif_a) failed\n");
+            abort();
+        }
+
+        do {
+            move_pkt(cur_ts, &nsif_a, &nsif_b);
+            move_pkt(cur_ts, &nsif_b, &nsif_a);
+            ts_a = netsim_n2d_timestamp(&nsif_a);
+            ts_b = netsim_n2d_timestamp(&nsif_b);
+        } while ((sync_a && ts_a <= cur_ts) ||
+                (sync_b && ts_b <= cur_ts));
+
+        if (sync_a && sync_b)
+            cur_ts = (ts_a <= ts_b ? ts_a : ts_b);
+        else if (sync_a)
+            cur_ts = ts_a;
+        else if (sync_b)
+            cur_ts = ts_b;
     }
     return 0;
 }

netsim_common/include/netsim.h

@@ -33,11 +33,15 @@ struct netsim_interface {
     size_t d2n_pos;
     size_t d2n_elen;
     size_t d2n_enum;
+    uint64_t d2n_timestamp;
 
     uint8_t *n2d_queue;
     size_t n2d_pos;
     size_t n2d_elen;
     size_t n2d_enum;
+    uint64_t n2d_timestamp;
+
+    int sync;
 };
 
 int netsim_init(struct netsim_interface *nsif,
@@ -45,11 +49,18 @@ int netsim_init(struct netsim_interface *nsif,
 void netsim_cleanup(struct netsim_interface *nsif);
 
 volatile union cosim_eth_proto_d2n *netsim_d2n_poll(
-        struct netsim_interface *nsif);
+        struct netsim_interface *nsif, uint64_t timestamp);
 void netsim_d2n_done(struct netsim_interface *nsif,
         volatile union cosim_eth_proto_d2n *msg);
 
 volatile union cosim_eth_proto_n2d *netsim_n2d_alloc(
-        struct netsim_interface *nsif);
+        struct netsim_interface *nsif, uint64_t timestamp,
+        uint64_t latency);
+int netsim_n2d_sync(struct netsim_interface *nsif, uint64_t timestamp,
+        uint64_t latency, uint64_t sync_delay);
+static inline uint64_t netsim_n2d_timestamp(struct netsim_interface *nsif)
+{
+    return nsif->n2d_timestamp;
+}
 
 #endif /* ndef COSIM_NETSIM_H_ */

netsim_common/netsim.c

@@ -62,8 +62,12 @@ int netsim_init(struct netsim_interface *nsif,
     }
     close(shm_fd);
 
-    if ((di.flags & COSIM_ETH_PROTO_FLAGS_DI_SYNC) == 0)
+    if ((di.flags & COSIM_ETH_PROTO_FLAGS_DI_SYNC) == 0) {
         *sync_eth = 0;
+        nsif->sync = 1;
+    } else {
+        nsif->sync = *sync_eth;
+    }
 
     nsif->d2n_queue = (uint8_t *) p + di.d2n_offset;
     nsif->n2d_queue = (uint8_t *) p + di.n2d_offset;
@@ -72,6 +76,7 @@ int netsim_init(struct netsim_interface *nsif,
     nsif->d2n_enum = di.d2n_nentries;
     nsif->n2d_enum = di.n2d_nentries;
     nsif->d2n_pos = nsif->n2d_pos = 0;
+    nsif->d2n_timestamp = nsif->n2d_timestamp = 0;
 
     return 0;
 }
@@ -83,7 +88,7 @@ void netsim_cleanup(struct netsim_interface *nsif)
 }
 
 volatile union cosim_eth_proto_d2n *netsim_d2n_poll(
-        struct netsim_interface *nsif)
+        struct netsim_interface *nsif, uint64_t timestamp)
 {
     volatile union cosim_eth_proto_d2n *msg =
         (volatile union cosim_eth_proto_d2n *)
@@ -94,6 +99,11 @@ volatile union cosim_eth_proto_d2n *netsim_d2n_poll(
             COSIM_ETH_PROTO_D2N_OWN_NET)
         return NULL;
 
+    /* if in sync mode, wait till message is ready */
+    nsif->d2n_timestamp = msg->dummy.timestamp;
+    if (nsif->sync && nsif->d2n_timestamp > timestamp)
+        return NULL;
+
     nsif->d2n_pos = (nsif->d2n_pos + 1) % nsif->d2n_enum;
     return msg;
 }
@@ -106,7 +116,8 @@ void netsim_d2n_done(struct netsim_interface *nsif,
 }
 
 volatile union cosim_eth_proto_n2d *netsim_n2d_alloc(
-        struct netsim_interface *nsif)
+        struct netsim_interface *nsif, uint64_t timestamp,
+        uint64_t latency)
 {
     volatile union cosim_eth_proto_n2d *msg =
         (volatile union cosim_eth_proto_n2d *)
@@ -118,6 +129,30 @@ volatile union cosim_eth_proto_n2d *netsim_n2d_alloc(
         return NULL;
     }
 
+    msg->dummy.timestamp = timestamp + latency;
+    nsif->n2d_timestamp = timestamp;
+
     nsif->n2d_pos = (nsif->n2d_pos + 1) % nsif->n2d_enum;
     return msg;
 }
+
+int netsim_n2d_sync(struct netsim_interface *nsif, uint64_t timestamp,
+        uint64_t latency, uint64_t sync_delay)
+{
+    volatile union cosim_eth_proto_n2d *msg;
+    volatile struct cosim_eth_proto_n2d_sync *sync;
+
+    if (nsif->n2d_timestamp != 0 &&
+            timestamp - nsif->n2d_timestamp < sync_delay)
+        return 0;
+
+    msg = netsim_n2d_alloc(nsif, timestamp, latency);
+    if (msg == NULL)
+        return -1;
+
+    sync = &msg->sync;
+    // WMB();
+    sync->own_type = COSIM_ETH_PROTO_N2D_MSG_SYNC | COSIM_ETH_PROTO_N2D_OWN_DEV;
+
+    return 0;
+}