Supercomputing 2011 ParalleX Demos using HPX

The STE||AR group will present two HPX demos at Supercomputing 2011 (LSU booth – 2839). These demos will highlight some of the capabilities any HPX application gains for free: active power management and automatic load balancing. If you are planning to visit Seattle for SC11 this year, please feel free to stop by. We will be happy to show you some of the possibilities of our parallel runtime system HPX.

Description of the two ParalleX demos for Supercomputing 2011:

Adaptive Mesh Refinement and Active Power Management Demonstration

In this example, an entire adaptive mesh refinement simulation (AMR) evolving a hyperbolic system of equations using RK3 integration in time and second order spatial differencing is demonstrated.

SC11 AMR demo

The shows a screenshot from the AMR demo using ParalleX. The binary system of neutron stars orbits several times during the simulation.

Power usage is externally measured using the “Watt’s Up” power meter.  Power usage is reported to the ipad interface:

The ipad interface displays the power usage externally measured by the "Watt's Up" meter. It also directly communicates with the HPX runtime system to control the thread managers of each core.

The ipad application directly communicates with the HPX runtime system and can control the activity of the thread managers.  A series of CPU kill-switches will toggle a particular thread manager associated with a specified core.  Turning off a core will reduce the speed of the simulation but also reduce power consumption.  The CPU clock speed can also be changed interactively through the ipad application.

A maximum power budget can be directly specified using the “Auto Power Management” tool in the upper right hand corner of the ipad application:

The "Auto Power Management" button opens a new dialogue where the user can specify the overall power budget for a given simulation. This tool will turn on or off thread managers in order to meet the specified power consumption limitation. When the auto-throttle client is active, the CPU killswitch is greyed out; however, it will reflect which cores are active based on the power budget supplied. The max power budget limit is indicated in the graph by the red line.

The HPX runtime system provides fine grained power management tools and performance counters that are independent of the application.  This will be especially useful in situations where power budgets are constrained and vary in time.

Symmetric contact for impulsive loading computations

In this example, various mesh objects consisting of different materials are interactively collided together.  Meshes are simple:  either rectangles or circles.  Material options include bread pudding, steel, and concrete.  The use selects the material type, mesh, and initial position/velocity of the object.

The ipad interface for selecting material type.

The ipad interface for selecting initial velocity.

Once the two objects are set on a collision course, the symmetric contact algorithm (implemented in HPX) ensures the conservation of momentum and the mesh surface is deformed accordingly.

A collision between a steel rectangle and a circle of bread pudding.

A collision between a steel rectangle and a concrete circle.

Symmetric contact algorithms rely on dynamic, adaptive, and irregular computations.  These algorithms have non uniform data access patterns which prevent the applications from taking advantage of data locality and fully utilizing the parallelism offered by the underlying system.  HPX provides data access asynchrony without blocking the critical execution path.  It does this by using futures based data access thereby achieving the on-demand access needed to more fully exploit the underlying resources in symmetric contact algorithms.

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