Expected Workflow¶

This guide will walk you through the expected workflow for using TraceR. It will direct you to resources on generating BigSim and OTF2 traces, the format of a TraceR configuration file, and a basic command for running a simulation.

TraceR is a replay tool targeted to simulate control flow of application on prototype systems, i.e., if control flow of an application, which includes expected computation tasks, communication routines, and their dependencies, is provided to TraceR, it will mimic the flow on a hypothetical system with a given compute and communication capability. As of now, the control flow is captured by either emulating applications using BigSim or by linking with Score-P. CODES is used for simulating the communication on the network.

Write an MPI application. (Avoid global variables so that the application be run with virtualization if using BigSim). Included in the TraceR repository are two examples: jacobi2d-bigsim and stencil4d-otf. The jacobi2d-bigsim example shows how a program would be compiled to generate BigSim traces, and the stencil4d-otf example shows how to compile a program for generating OTF2 traces.

Note

If you’re using BigSim, avoid global variables in your MPI application so that it can be run with virtualization.
Generate traces. For instructions on generating OTF2 traces, see the user guide section on using Score-P, or for using BigSim traces see the section in the user guide about BigSim.
After generating traces, 2 files are needed: a tracer config file, and a codes config file. Optionally, mapping files can also be provided. See Creating a TraceR configuration file, Creating the network (CODES) configuration file, and Creating the job placement file in the user guide for instructions on creating the files.
Run the simulation using mpirun. For details on options available, see the Quickstart section in the user guide. This command will run a simulation in optimistic mode:
```
mpirun -np <p> ../traceR --sync=3  -- <network_config> <tracer_config>
```