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ariel

The ariel library models a multicore CPU using a dynamic application trace. The CPU models memory accesses in detail and non-memory accesses as a single cycle operation. Instruction dependencies are not tracked. The ariel library divides the simulation into two parts: a frontend that provides a trace, and a CPU simulation model that consumes the trace and provides the modeling itself. The framework includes two frontends: one that uses Pin and one that uses PEBIL or EPAX. Both generate the trace while the application runs, but Pin instruments the application dynamically, while PEBIL (x86) and EPAX (Arm) instrument the binary statically ahead of time. PEBIL supports sampling, which can improve simulation time. Running applications may use threads and/or MPI. Ariel supports memory models that use the StandardMem interface.

At a Glance

Source Code: sst-elements/.../ariel  
SST Name: ariel  
Maturity Level: Mature (3)  
Development Path: Active  
Last Released: SST 16.1

Required dependencies​

None to build Ariel.

To run a simulation, however, Ariel needs a frontend to trace the application, which in turn needs a binary instrumentation tool. Ariel stops with an error at startup if it cannot load a frontend. Use one of the following:

  • Pin 3 Used by the default frontend, ariel.frontend.pin. Ariel must be configured with --with-pin; without Pin, this frontend is not built.
  • PEBIL (x86) or EPAX (Arm) Used by the ariel.frontend.epa frontend, which is always built. Run the frontend on an application that was already instrumented with one of these tools.
  • A custom frontend Supply your own frontend SubComponent in the frontend slot of the Ariel component in the input file. The custom frontend must implement the SST::ArielComponent::ArielFrontend API.

Optional dependencies​

  • zlib Enables generating a compressed execution trace

Selecting a frontend​

By default, Ariel loads ariel.frontend.pin. To use a different frontend, set the Ariel frontend parameter, or load a frontend SubComponent into the frontend slot.

import sst

ariel = sst.Component("cpu", "ariel.ariel")
ariel.addParams({
    "corecount" : 1,
    "executable" : "./app.arielinst",   # Application instrumented with PEBIL or EPAX
    "frontend" : "ariel.frontend.epa",
})

Elements​

Use sst-info ariel or sst-info ariel.<element> to see each element's parameters, ports, and statistics.

LibraryElementTypeDescription
arielarielComponentCPU model driven by a dynamic trace of a running application; the trace comes from the frontend in its frontend slot or frontend parameter
arielfrontend.pinSubComponentDefault frontend; traces the application with Pin 3. Built only when configured with --with-pin
arielfrontend.epaSubComponentFrontend for applications already instrumented with PEBIL (x86) or EPAX (Arm)
arielMemoryManagerSimpleSubComponentDefault memory manager for the memmgr slot; maps each virtual page to a physical page the first time it is touched
arielMemoryManagerMallocSubComponentMemory manager for the memmgr slot that supports malloc/free into different memory pools (multi-level memory)
arielTextTraceGeneratorModuleWrites traced memory operations to a text file; selected with the tracegen parameter
arielCompressedBinaryTraceGeneratorModuleWrites traced memory operations to a compressed binary file; selected with the tracegen parameter. Built only when zlib is found