6,729 research outputs found
Energy-Efficient Scheduling for Homogeneous Multiprocessor Systems
We present a number of novel algorithms, based on mathematical optimization
formulations, in order to solve a homogeneous multiprocessor scheduling
problem, while minimizing the total energy consumption. In particular, for a
system with a discrete speed set, we propose solving a tractable linear
program. Our formulations are based on a fluid model and a global scheduling
scheme, i.e. tasks are allowed to migrate between processors. The new methods
are compared with three global energy/feasibility optimal workload allocation
formulations. Simulation results illustrate that our methods achieve both
feasibility and energy optimality and outperform existing methods for
constrained deadline tasksets. Specifically, the results provided by our
algorithm can achieve up to an 80% saving compared to an algorithm without a
frequency scaling scheme and up to 70% saving compared to a constant frequency
scaling scheme for some simulated tasksets. Another benefit is that our
algorithms can solve the scheduling problem in one step instead of using a
recursive scheme. Moreover, our formulations can solve a more general class of
scheduling problems, i.e. any periodic real-time taskset with arbitrary
deadline. Lastly, our algorithms can be applied to both online and offline
scheduling schemes.Comment: Corrected typos: definition of J_i in Section 2.1; (3b)-(3c);
definition of \Phi_A and \Phi_D in paragraph after (6b). Previous equations
were correct only for special case of p_i=d_
Simulating spin models on GPU
Over the last couple of years it has been realized that the vast
computational power of graphics processing units (GPUs) could be harvested for
purposes other than the video game industry. This power, which at least
nominally exceeds that of current CPUs by large factors, results from the
relative simplicity of the GPU architectures as compared to CPUs, combined with
a large number of parallel processing units on a single chip. To benefit from
this setup for general computing purposes, the problems at hand need to be
prepared in a way to profit from the inherent parallelism and hierarchical
structure of memory accesses. In this contribution I discuss the performance
potential for simulating spin models, such as the Ising model, on GPU as
compared to conventional simulations on CPU.Comment: 5 pages, 4 figures, elsarticl
Interval simulation: raising the level of abstraction in architectural simulation
Detailed architectural simulators suffer from a long development cycle and extremely long evaluation times. This longstanding problem is further exacerbated in the multi-core processor era. Existing solutions address the simulation problem by either sampling the simulated instruction stream or by mapping the simulation models on FPGAs; these approaches achieve substantial simulation speedups while simulating performance in a cycle-accurate manner This paper proposes interval simulation which rakes a completely different approach: interval simulation raises the level of abstraction and replaces the core-level cycle-accurate simulation model by a mechanistic analytical model. The analytical model estimates core-level performance by analyzing intervals, or the timing between two miss events (branch mispredictions and TLB/cache misses); the miss events are determined through simulation of the memory hierarchy, cache coherence protocol, interconnection network and branch predictor By raising the level of abstraction, interval simulation reduces both development time and evaluation time. Our experimental results using the SPEC CPU2000 and PARSEC benchmark suites and the MS multi-core simulator show good accuracy up to eight cores (average error of 4.6% and max error of 11% for the multi-threaded full-system workloads), while achieving a one order of magnitude simulation speedup compared to cycle-accurate simulation. Moreover interval simulation is easy to implement: our implementation of the mechanistic analytical model incurs only one thousand lines of code. Its high accuracy, fast simulation speed and ease-of-use make interval simulation a useful complement to the architect's toolbox for exploring system-level and high-level micro-architecture trade-offs
Radiation safety based on the sky shine effect in reactor
In the reactor operation, neutrons and gamma rays are the most dominant radiation.
As protection, lead and concrete shields are built around the reactor. However, the radiation
can penetrate the water shielding inside the reactor pool. This incident leads to the occurrence
of sky shine where a physical phenomenon of nuclear radiation sources was transmitted
panoramic that extends to the environment. The effect of this phenomenon is caused by the
fallout radiation into the surrounding area which causes the radiation dose to increase. High
doses of exposure cause a person to have stochastic effects or deterministic effects. Therefore,
this study was conducted to measure the radiation dose from sky shine effect that scattered
around the reactor at different distances and different height above the reactor platform. In this
paper, the analysis of the radiation dose of sky shine effect was measured using the
experimental metho
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