Difference between revisions of "Garnet Synthetic Traffic"
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| '''--network''' || Network model: simple or garnet2.0. Use garnet2.0 for running synthetic traffic. | | '''--network''' || Network model: simple or garnet2.0. Use garnet2.0 for running synthetic traffic. | ||
|- | |- | ||
| − | | '''--topology''' || Topology for connecting the cpus and dirs to the network routers/switches | + | | '''--topology''' || Topology for connecting the cpus and dirs to the network routers/switches. More detail about different topologies can be found [[Interconnection_Network#Topology|here]]. |
|- | |- | ||
| '''--mesh-rows''' || The number of rows in the mesh. Only valid when ''--topology'' is ''Mesh_*'' or ''MeshDirCorners_*''. | | '''--mesh-rows''' || The number of rows in the mesh. Only valid when ''--topology'' is ''Mesh_*'' or ''MeshDirCorners_*''. | ||
Revision as of 21:55, 11 September 2016
The Garnet Synthetic Traffic provides a framework for simulating the garnet network with controlled inputs. This is useful for network testing/debugging, or for network-only simulations with synthetic traffic. The injector only works with the Garnet_standalone coherence protocol.
Contents
Related Files
- configs/example/garnet_synth_traffic.py: file to invoke the network tester
- src/cpu/testers/garnet_synthetic_traffic: files implementing the tester.
- GarnetSyntheticTraffic.py
- GarnetSyntheticTraffic.hh
- GarnetSyntheticTraffic.cc
How to run
First build gem5 with the Garnet_standalone coherence protocol:
scons build/Garnet_standalone/gem5.debug
Example command:
./build/Garnet_standalone/gem5.debug configs/example/garnet_synth_traffic.py \ --num-cpus=16 \ --num-dirs=16 \ --network=garnet2.0 \ --topology=Mesh_XY \ --mesh-rows=4 \ --sim-cycles=1000 \ --synthetic=uniform_random \ --injectionrate=0.01
Parameterized Options
| System Configuration | Description |
|---|---|
| --num-cpus | Number of cpus. This is the number of source (injection) nodes in the network. |
| --num-dirs | Number of directories. This is the number of destination (ejection) nodes in the network. |
| --network | Network model: simple or garnet2.0. Use garnet2.0 for running synthetic traffic. |
| --topology | Topology for connecting the cpus and dirs to the network routers/switches. More detail about different topologies can be found here. |
| --mesh-rows | The number of rows in the mesh. Only valid when --topology is Mesh_* or MeshDirCorners_*. |
| Network Configuration | Description |
|---|---|
| --router-latency | Default number of pipeline stages in the garnet router. Has to be >= 1. Can be over-ridden on a per router basis in the topology file. |
| --link-latency | Default latency of each link in the network. Has to be >= 1. Can be over-ridden on a per link basis in the topology file. |
| --vcs-per-vnet | Number of VCs per Virtual Network. |
| --link-width-bits | Width in bits for all links inside the garnet network. Default = 128. |
| Traffic Injection | Description |
|---|---|
| --sim-cycles | Total number of cycles for which the simulation should run. |
| --synthetic | The type of synthetic traffic to be injected. The following synthetic traffic patterns are currently supported: 'uniform_random', 'tornado', 'bit_complement', 'bit_reverse', 'bit_rotation', 'neighbor', 'shuffle', and 'transpose'. |
| --injectionrate | Traffic Injection Rate in packets/node/cycle. It can take any decimal value between 0 and 1. The number of digits of precision after the decimal point can be controlled by --precision which is set to 3 as default in garnet_synth_traffic.py. |
| --single-sender-id | Only inject from this sender. To send from all nodes, set to -1. |
| --single-dest-id | Only send to this destination. To send to all destinations as specified by the synthetic traffic pattern, set to -1. |
| --num-packets-max | Maximum number of packets to be injected by each cpu node. Default value is -1 (keep injecting till sim-cycles). |
| --inj-vnet | Only inject in this vnet (0, 1 or 2). 0 and 1 are 1-flit, 2 is 5-flit. Set to -1 to inject randomly in all vnets. |
Implementation of Garnet synthetic traffic
The synthetic traffic injector is implemented in GarnetSyntheticTraffic.cc. The sequence of steps involved in generating and sending a packet are as follows.
- Every cycle, each cpu performs a bernouli trial with probability equal to --injectionrate to determine whether to generate a packet or not.
- If --num-packets-max is non negative, each cpu stops generating new packets after generating --num-packets-max number of packets. The injector terminates after --sim-cycles.
- If the cpu has to generate a new packet, it computes the destination for the new packet based on the synthetic traffic type (--synthetic).
- This destination is embedded into the bits after block offset in the packet address.
- The generated packet is randomly tagged as a ReadReq, or an INST_FETCH, or a WriteReq, and sent to the Ruby Port (src/mem/ruby/system/RubyPort.hh/cc).
- The Ruby Port converts the packet into a RubyRequestType:LD, RubyRequestType:IFETCH, and RubyRequestType:ST, respectively, and sends it to the Sequencer, which in turn sends it to the Garnet_standalone cache controller.
- The cache controller extracts the destination directory from the packet address.
- The cache controller injects the LD, IFETCH and ST into virtual networks 0, 1 and 2 respectively.
- LD and IFETCH are injected as control packets (8 bytes), while ST is injected as a data packet (72 bytes).
- The packet traverses the network and reaches the directory.
- The directory controller simply drops it.
