Simulating network flow control

At least one non-transitory machine readable storage medium with instructions stored thereon, the instructions executable to cause a machine to:

• emulate operation of a first hardware device in a simulation of a computing system, wherein the first hardware device is emulated through a first device model to be included in the computing system, wherein the first device model comprises a fixed-size receive buffer;
• monitor a receive buffer in the first device model to determine whether capacity exists in the receive buffer to receive a new packet;
• send a query to a communication runtime to determine whether any packets destined for the first device model are buffered in an internal buffer of the communication runtime, wherein the communication runtime is used to implement the simulation and facilitates communication between a plurality of device models;
• receive a response to the query from the communication runtime, wherein the response identifies a particular packet stored in the internal buffer of the communication runtime for the first device model, the particular packet was delivered to the communication runtime by a second device model, and the second device model emulates another device in the computing system;
• receive the particular packet at the first device model from the communication runtime;
• and
• process the particular packet at the first device model.

A system comprising:

• a processor;
• a memory;
• and
• a system simulator executable by the processor to simulate operations of a plurality of interconnected devices in a simulation of a computing system, wherein the system simulator is to implement a communication runtime in the simulation to implement simulated communications between the plurality of interconnect devices in the simulation, and the communication runtime is to:
• receive a packet generated by a simulation of a first one of the plurality of devices to be sent to a simulation of a second one of the plurality of devices in the simulation;
• buffer the packet in an internal buffer of the communication runtime;
• receive, at the communication runtime, a query from the simulation of the second device, wherein the query identifies that a receive buffer of the simulation of the second device has capacity, and the receive buffer of the simulation of the second device is to simulate a fixed-size buffer of the second device;
• and
• send the packet from the internal buffer of the communication runtime to the simulation of the second device based on the query to simulate transmission of the packet from the first device to the second device on a link.