Add support for a propagation delay on the link. The electrical

delay is more or less folded into the packet time, but an additional
delay is possible representing crossing a long haul link, or some
switches, etc.

--HG--
extra : convert_revision : 8fd689c2a7e3051e77f47a4cd5f51c6999d92c8f

2 files changed, 121 insertions, 41 deletions

diff --git a/dev/etherlink.cc b/dev/etherlink.cc
index 6396d758d..25991f1a7 100644
--- a/dev/etherlink.cc
+++ b/dev/etherlink.cc
@@ -46,14 +46,15 @@
 
 using namespace std;
 
-EtherLink::EtherLink(const std::string &name, EtherInt *i1, EtherInt *i2,
-                     Tick speed, EtherDump *dump)
+EtherLink::EtherLink(const string &name, EtherInt *i1, EtherInt *i2,
+                     Tick speed, Tick dly, EtherDump *dump)
     : SimObject(name)
 {
     double rate = ((double)ticksPerSecond * 8.0) / (double)speed;
+    Tick delay = US2Ticks(dly);
 
-    link1 = new Link(name + ".link1", rate, dump);
-    link2 = new Link(name + ".link2", rate, dump);
+    link1 = new Link(name + ".link1", rate, delay, dump);
+    link2 = new Link(name + ".link2", rate, delay, dump);
 
     int1 = new Interface(name + ".int1", link1, link2);
     int2 = new Interface(name + ".int2", link2, link1);
@@ -73,16 +74,17 @@ EtherLink::~EtherLink()
     delete int2;
 }
 
-EtherLink::Interface::Interface(const std::string &name, Link *tx, Link *rx)
+EtherLink::Interface::Interface(const string &name, Link *tx, Link *rx)
     : EtherInt(name), txlink(tx)
 {
     tx->setTxInt(this);
     rx->setRxInt(this);
 }
 
-EtherLink::Link::Link(const std::string &name, double rate, EtherDump *d)
-    : objName(name), txint(NULL), rxint(NULL), ticks_per_byte(rate),
-      dump(d), event(&mainEventQueue, this)
+EtherLink::Link::Link(const string &name, double rate, Tick delay,
+                      EtherDump *d)
+    : objName(name), txint(NULL), rxint(NULL), ticksPerByte(rate),
+      linkDelay(delay), dump(d), doneEvent(this)
 {}
 
 void
@@ -102,15 +104,46 @@ EtherLink::unserialize(Checkpoint *cp, const string &section)
 }
 
 void
+EtherLink::Link::txComplete(PacketPtr &packet)
+{
+    DPRINTF(Ethernet, "packet received: len=%d\n", packet->length);
+    DDUMP(EthernetData, packet->data, packet->length);
+    rxint->sendPacket(packet);
+}
+
+class LinkDelayEvent : public Event
+{
+  protected:
+    EtherLink::Link *link;
+    PacketPtr packet;
+
+    // non-scheduling version for createForUnserialize()
+    LinkDelayEvent(EtherLink::Link *link);
+
+  public:
+    LinkDelayEvent(EtherLink::Link *link, PacketPtr &pkt, Tick when);
+
+    void process();
+
+    virtual void serialize(ostream &os);
+    virtual void unserialize(Checkpoint *cp, const string &section);
+    static Serializable *createForUnserialize(Checkpoint *cp,
+                                              const string &section);
+};
+
+
+void
 EtherLink::Link::txDone()
 {
     if (dump)
         dump->dump(packet);
 
-    DPRINTF(Ethernet, "EtherLink packet received: len=%d\n", packet->length);
-    DDUMP(EthernetData, packet->data, packet->length);
-
-    rxint->sendPacket(packet);
+    if (linkDelay > 0) {
+        DPRINTF(Ethernet, "packet delayed: delay=%d\n", linkDelay);
+        new LinkDelayEvent(this, packet, curTick + linkDelay);
+    } else {
+        txComplete(packet);
+    }
 
     packet = 0;
     assert(!busy());
@@ -122,18 +155,18 @@ bool
 EtherLink::Link::transmit(PacketPtr &pkt)
 {
     if (busy()) {
-        DPRINTF(Ethernet, "EtherLink packet not sent, link busy\n");
+        DPRINTF(Ethernet, "packet not sent, link busy\n");
         return false;
     }
 
-    DPRINTF(Ethernet, "EtherLink packet sent: len=%d\n", pkt->length);
+    DPRINTF(Ethernet, "packet sent: len=%d\n", pkt->length);
     DDUMP(EthernetData, pkt->data, pkt->length);
 
     packet = pkt;
-    int delay = (int)ceil(((double)pkt->length * ticks_per_byte) + 1.0);
-    DPRINTF(Ethernet, "EtherLink scheduling packet: delay=%d, (rate=%f)\n",
-            delay, ticks_per_byte);
-    event.schedule(curTick + delay);
+    Tick delay = (Tick)ceil(((double)pkt->length * ticksPerByte) + 1.0);
+    DPRINTF(Ethernet, "scheduling packet: delay=%d, (rate=%f)\n",
+            delay, ticksPerByte);
+    doneEvent.schedule(curTick + delay);
 
     return true;
 }
@@ -144,10 +177,10 @@ EtherLink::Link::serialize(ostream &os)
     bool packet_exists = packet;
     SERIALIZE_SCALAR(packet_exists);
 
-    bool event_scheduled = event.scheduled();
+    bool event_scheduled = doneEvent.scheduled();
     SERIALIZE_SCALAR(event_scheduled);
     if (event_scheduled) {
-        Tick event_time = event.when();
+        Tick event_time = doneEvent.when();
         SERIALIZE_SCALAR(event_time);
     }
 
@@ -172,15 +205,68 @@ EtherLink::Link::unserialize(Checkpoint *cp, const string &section)
     if (event_scheduled) {
         Tick event_time;
         UNSERIALIZE_SCALAR(event_time);
-        event.schedule(event_time);
+        doneEvent.schedule(event_time);
     }
 }
 
+LinkDelayEvent::LinkDelayEvent(EtherLink::Link *l)
+    : Event(&mainEventQueue), link(l)
+{
+    setFlags(AutoSerialize);
+    setFlags(AutoDelete);
+}
+
+LinkDelayEvent::LinkDelayEvent(EtherLink::Link *l, PacketPtr &p, Tick when)
+    : Event(&mainEventQueue), link(l), packet(p)
+{
+    setFlags(AutoSerialize);
+    setFlags(AutoDelete);
+    schedule(when);
+}
+
+void
+LinkDelayEvent::process()
+{
+    link->txComplete(packet);
+}
+
+void
+LinkDelayEvent::serialize(ostream &os)
+{
+    paramOut(os, "type", string("LinkDelayEvent"));
+    Event::serialize(os);
+    SERIALIZE_OBJPTR(link);
+
+    nameOut(os, csprintf("%s.packet", name()));
+    packet->serialize(os);
+}
+
+
+void
+LinkDelayEvent::unserialize(Checkpoint *cp, const string &section)
+{
+    Event::unserialize(cp, section);
+    packet = new EtherPacket;
+    packet->unserialize(cp, csprintf("%s.packet", section));
+}
+
+
+Serializable *
+LinkDelayEvent::createForUnserialize(Checkpoint *cp, const string &section)
+{
+    EtherLink::Link *link;
+    UNSERIALIZE_OBJPTR(link);
+    return new LinkDelayEvent(link);
+}
+
+REGISTER_SERIALIZEABLE("LinkDelayEvent", LinkDelayEvent)
+
 BEGIN_DECLARE_SIM_OBJECT_PARAMS(EtherLink)
 
     SimObjectParam<EtherInt *> interface1;
     SimObjectParam<EtherInt *> interface2;
     Param<Tick> link_speed;
+    Param<Tick> link_delay;
     SimObjectParam<EtherDump *> packet_dump;
 
 END_DECLARE_SIM_OBJECT_PARAMS(EtherLink)
@@ -190,6 +276,7 @@ BEGIN_INIT_SIM_OBJECT_PARAMS(EtherLink)
     INIT_PARAM(interface1, "interface 1"),
     INIT_PARAM(interface2, "interface 2"),
     INIT_PARAM_DFLT(link_speed, "link speed in bits per second", 100000000),
+    INIT_PARAM_DFLT(link_delay, "transmit delay of packets in us", 0),
     INIT_PARAM_DFLT(packet_dump, "object to dump network packets to", NULL)
 
 END_INIT_SIM_OBJECT_PARAMS(EtherLink)
@@ -197,7 +284,7 @@ END_INIT_SIM_OBJECT_PARAMS(EtherLink)
 CREATE_SIM_OBJECT(EtherLink)
 {
     return new EtherLink(getInstanceName(), interface1, interface2, link_speed,
-                         packet_dump);
+                         link_delay, packet_dump);
 }
 
 REGISTER_SIM_OBJECT("EtherLink", EtherLink)
diff --git a/dev/etherlink.hh b/dev/etherlink.hh
index 8505570a6..3b1dd21bc 100644
--- a/dev/etherlink.hh
+++ b/dev/etherlink.hh
@@ -49,6 +49,7 @@ class EtherLink : public SimObject
   protected:
     class Interface;
 
+    friend class LinkDelayEvent;
      /*
       * Model for a single uni-directional link
       */
@@ -59,34 +60,26 @@ class EtherLink : public SimObject
         Interface *txint;
         Interface *rxint;
 
-        double ticks_per_byte;
+        double ticksPerByte;
+        Tick linkDelay;
         EtherDump *dump;
 
       protected:
         /*
          * Transfer is complete
          */
-        class DoneEvent : public Event
-        {
-          protected:
-            Link *link;
-
-          public:
-            DoneEvent(EventQueue *q, Link *l)
-                : Event(q), link(l) {}
-            virtual void process() { link->txDone(); }
-            virtual const char *description()
-                { return "ethernet link completion"; }
-        };
-
-        friend class DoneEvent;
-        DoneEvent event;
         PacketPtr packet;
-
         void txDone();
+        typedef EventWrapper<Link, &Link::txDone> DoneEvent;
+        friend class DoneEvent;
+        DoneEvent doneEvent;
+
+        friend class LinkDelayEvent;
+        void txComplete(PacketPtr &packet);
 
       public:
-        Link(const std::string &name, double rate, EtherDump *dump);
+        Link(const std::string &name, double rate, Tick delay,
+             EtherDump *dump);
         ~Link() {}
 
         virtual const std::string name() const { return objName; }
@@ -123,7 +116,7 @@ class EtherLink : public SimObject
 
   public:
     EtherLink(const std::string &name, EtherInt *i1, EtherInt *i2,
-              Tick speed, EtherDump *dump);
+              Tick speed, Tick delay, EtherDump *dump);
     virtual ~EtherLink();
 
     virtual void serialize(std::ostream &os);