BookSim 2.0 Interconnection Network Simulator

BookSim is a cycle-accurate interconnection network simulator. It is designed to simulate various network topologies, routing algorithms, and router microarchitectures.

Key features of BookSim 2.0 include:

• Topology Support: Supports mesh, torus, flattened butterfly, and other network structures.
• Routing: Provides diverse routing algorithms.
• Customization: Offers numerous options for customizing router microarchitecture.

This tool is commonly used in research for evaluating interconnection networks.

The Tree4 class implements a network topology consisting of 64 terminal nodes arranged in a tree structure with 4 routers at the root. It is a subclass of Network and can be instantiated using a Configuration object and a name string. This topology provides utility methods to map node IDs to their specific height and position within the tree, which is useful for custom routing or analysis.

// Example instantiation (conceptual)
Tree4 my_tree(config, "my_tree_network");

The CMesh class implements a Mesh topology that supports concentration and express links along the network edges. It is initialized via the CMesh constructor, which requires a Configuration object and a name string. The topology's dimensions and features (like express channels) are determined by the parameters provided in the Configuration object.

CMesh my_network(config, "my_cmesh_network");

BookSim provides two primary implementations of the Allocator interface, which can be selected via the alloc_type string in NewAllocator:

1. DenseAllocator: Stores the entire request matrix. This is useful for smaller port counts where the overhead of a full matrix is negligible or when specific matrix-based access patterns are required.
2. SparseAllocator: Uses sets and maps to store only active requests. This implementation is more memory-efficient for large-scale networks where the number of concurrent requests is much smaller than the total possible input-output combinations.

The FlitChannel class is used to model a communication channel between routers that transmits Flit objects. It supports a multi-cycle transmission delay, where the latency can be specified as an integer number of simulator cycles.

To use a FlitChannel, you must define its source and sink routers and their respective ports using SetSource and SetSink.

// Conceptual usage pattern for setting up a channel between routers
FlitChannel* channel = new FlitChannel(parent_module, "my_channel", num_classes);
channel->SetSource(source_router, source_port);
channel->SetSink(sink_router, sink_port);

The FeedbackSharedBufferPolicy is a sophisticated policy that adjusts buffer limits based on network latency. It uses the following internal parameters (set via Configuration during construction):

• _min_latency: The minimum expected latency used in RTT calculations.
• _aging_scale: Scaling factor for aging/feedback logic.
• _offset: An offset used in limit calculations.
• _total_mapped_size: The total buffer capacity available to the policy.

You can explicitly set the minimum latency using the SetMinLatency(int min_latency) method on the BufferState object, which propagates the call to the underlying policy.

BookSim uses a BookSimConfig object to manage simulation settings. Parameters can be provided via a configuration file or as command-line arguments.

Key configuration keys identified in the entrypoint include:

• subnets: Integer specifying the number of networks to initialize.
• sim_power: Integer used to trigger power analysis (if > 0).
• print_activity: Boolean/Integer to enable activity printing.
• viewer_trace: Boolean/Integer to enable NoCViewer trace generation.
• watch_out: String specifying the output file for the watch stream. Use "-" to redirect to stdout or leave empty for no output.

If you use BookSim in your research, please cite the following paper in your publications:

Nan Jiang, Daniel U. Becker, George Michelogiannakis, James Balfour, Brian Towles, John Kim and William J. Dally. A Detailed and Flexible Cycle-Accurate Network-on-Chip Simulator. In Proceedings of the 2013 IEEE International Symposium on Performance Analysis of Systems and Software, 2013.

The QTree class provides an implementation of a Quad-Tree indirect network. It inherits from the Network base class and is initialized using a Configuration object and a name string. The topology is defined by its height and position within the tree structure, which can be derived from a unique node ID using static helper methods.

// Example instantiation of a QTree network
QTree my_qtree(config, "my_qtree_name");