Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

This paper presents and characterizes Rodinia, a benchmark suite for heterogeneous computing. To help architects study emerging platforms such as GPUs (Graphics Processing Units), Rodinia includes applications and kernels which target multi-core CPU and GPU platforms. The choice of applications is inspired by Berkeley's dwarf taxonomy. Our characterization shows that the Rodinia benchmarks cover a wide range of parallel communication patterns, synchronization techniques and power consumption, and has led to some important architectural insight, such as the growing importance of memory-bandwidth limitations and the consequent importance of data layout.

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Rodinia: A benchmark suite for heterogeneous computing

Emerging challenges and materials for thermal management of electronics

With power density and hence cooling costs rising exponentially, processor packaging can no longer be designed for the worst case, and there is an urgent need for runtime processor-level techniques that can regulate operating temperature when the package's capacity is exceeded. Evaluating such techniques, however, requires a thermal model that is practical for architectural studies.This paper describes HotSpot, an accurate yet fast model based on an equivalent circuit of thermal resistances and capacitances that correspond to microarchitecture blocks and essential aspects of the thermal package. Validation was performed using finite-element simulation. The paper also introduces several effective methods for dynamic thermal management (DTM): "temperature-tracking" frequency scaling, localized toggling, and migrating computation to spare hardware units. Modeling temperature at the microarchitecture level also shows that power metrics are poor predictors of temperature, and that sensor imprecision has a substantial impact on the performance of DTM.

Temperature-aware microarchitecture

This paper presents HotSpot-a modeling methodology for developing compact thermal models based on the popular stacked-layer packaging scheme in modern very large-scale integration systems. In addition to modeling silicon and packaging layers, HotSpot includes a high-level on-chip interconnect self-heating power and thermal model such that the thermal impacts on interconnects can also be considered during early design stages. The HotSpot compact thermal modeling approach is especially well suited for preregister transfer level (RTL) and presynthesis thermal analysis and is able to provide detailed static and transient temperature information across the die and the package, as it is also computationally efficient.

/pdf/hotspot-a-compact-thermal-modeling-methodology-for-early-43x1muqtv2.pdf

HotSpot: a compact thermal modeling methodology for early-stage VLSI design

A mechanism is provided for minimizing system power in the data processing system with fast convergence. A current aggregate system power value is determined using a current thermal threshold value. For each potential thermal threshold value in a set of potential thermal threshold values, a determination is made as to whether there is a potential thermal threshold value that results in a potential aggregate system power value that is lower than the current aggregate system power value. Responsive to identifying an optimal potential thermal threshold value from the set of potential thermal threshold values that results in minimum aggregate system power value that is lower than the current aggregate system power value, the optimal potential thermal threshold value is set as a new thermal threshold value.

Minimizing aggregate cooling and leakage power with fast convergence

Systems, apparatuses, and methods for performing real-time tracking of performance targets using dynamic compilation. A performance target is specified in a service level agreement. A dynamic compiler analyzes a software application executing in real-time and determine which high-level application metrics to track. The dynamic compiler then inserts instructions into the code to increment counters associated with the metrics. A power optimization unit then utilizes the counters to determine if the system is currently meeting the performance target. If the system is exceeding the performance target, then the power optimization unit reduces the power consumption of the system while still meeting the performance target.

Real-time performance tracking using dynamic compilation

https://www.cs.virginia.edu/~skadron/Papers/sankaranarayanan_thermal_integration12.pdf

Architectural implications of spatial thermal filtering

A decoupling control strategy of three-phase inverter, which can realize complete decoupling of the active and reactive current in the synchronous reference frame (SRF) is proposed here. There are two coupling factors of current loop in SRF, one is time delay caused by digital control, and the other is AC filter. Dynamic time delay compensation is applied to eliminate coupling caused by the first factor. The phase of the bridge leg voltage can be predicted. The difference between it and the phase of reference voltage which takes part in pulse width modulation (PWM) is the dynamic compensation angle, which can compensate the time delay. High-order feedforward compensation is applied to eliminate coupling caused by the second factor. Complex vector model of the LCL filter is derived and the high-order coupling coefficients can be offset by feedforward compensation. The coupling characteristics and compensation principles are analysed in detail. The system stability is discussed. Finally, the simulation and experimental results are given to verify the theoretical analysis. 

Complete decoupling compensation of three‐phase inverter with LCL filter in synchronous reference frame

A three-dimensional (3-D) processor stack includes a plurality of processor cores implemented in a plurality of layers. A controller is to selectively throttle one or more of a plurality of processor cores in response to detecting a thermal event. The controller selectively throttles the one or more of the plurality of processor cores based on values of thermal couplings between the plurality of layers and based on measures of criticality of threads executing on the plurality of processor cores.

Wei Huang

Papers

Minimizing aggregate cooling and leakage power with fast convergence

Real-time performance tracking using dynamic compilation

Architectural implications of spatial thermal filtering

Complete decoupling compensation of three‐phase inverter with LCL filter in synchronous reference frame

Thermally-aware throttling in a three-dimensional processor stack