dev: add support for multi gem5 runs

Multi gem5 is an extension to gem5 to enable parallel simulation of a
distributed system (e.g. simulation of a pool of machines
connected by Ethernet links). A multi gem5 run consists of seperate gem5
processes running in parallel (potentially on different hosts/slots on
a cluster). Each gem5 process executes the simulation of a component of the
simulated distributed system (e.g. a multi-core board with an Ethernet NIC).

The patch implements the "distributed" Ethernet link device
(dev/src/multi_etherlink.[hh.cc]). This device will send/receive
(simulated) Ethernet packets to/from peer gem5 processes. The interface
to talk to the peer gem5 processes is defined in dev/src/multi_iface.hh and
in tcp_iface.hh.

There is also a central message server process (util/multi/tcp_server.[hh,cc])
which acts like an Ethernet switch and transfers messages among the gem5 peers.

A multi gem5 simulations can be kicked off by the util/multi/gem5-multi.sh
wrapper script.

Checkpoints are supported by multi-gem5. The checkpoint must be
initiated by a single gem5 process. E.g., the gem5 process with rank 0
can take a checkpoint from the bootscript just before it invokes
'mpirun' to launch an MPI test. The message server process will notify
all the other peer gem5 processes and make them take a checkpoint, too
(after completing a global synchronisation to ensure that there are no
inflight messages among gem5).

1 files changed, 26 insertions, 0 deletions

diff --git a/src/dev/Ethernet.py b/src/dev/Ethernet.py
index 147ad156c..84fa0ae00 100644
--- a/src/dev/Ethernet.py
+++ b/src/dev/Ethernet.py
@@ -1,3 +1,15 @@
+# Copyright (c) 2015 ARM Limited
+# All rights reserved.
+#
+# The license below extends only to copyright in the software and shall
+# not be construed as granting a license to any other intellectual
+# property including but not limited to intellectual property relating
+# to a hardware implementation of the functionality of the software
+# licensed hereunder.  You may use the software subject to the license
+# terms below provided that you ensure that this notice is replicated
+# unmodified and in its entirety in all distributions of the software,
+# modified or unmodified, in source code or in binary form.
+#
 # Copyright (c) 2005-2007 The Regents of The University of Michigan
 # All rights reserved.
 #
@@ -46,6 +58,20 @@ class EtherLink(EtherObject):
     speed = Param.NetworkBandwidth('1Gbps', "link speed")
     dump = Param.EtherDump(NULL, "dump object")
 
+class MultiEtherLink(EtherObject):
+    type = 'MultiEtherLink'
+    cxx_header = "dev/multi_etherlink.hh"
+    int0 = SlavePort("interface 0")
+    delay = Param.Latency('0us', "packet transmit delay")
+    delay_var = Param.Latency('0ns', "packet transmit delay variability")
+    speed = Param.NetworkBandwidth('1Gbps', "link speed")
+    dump = Param.EtherDump(NULL, "dump object")
+    multi_rank  =  Param.UInt32('0', "Rank of the this gem5 process (multi run)")
+    sync_start  = Param.Latency('5200000000000t', "first multi sync barrier")
+    sync_repeat = Param.Latency('10us', "multi sync barrier repeat")
+    server_name = Param.String('localhost', "Message server name")
+    server_port = Param.UInt32('2200', "Message server port")
+
 class EtherBus(EtherObject):
     type = 'EtherBus'
     cxx_header = "dev/etherbus.hh"