NMath Premium is our brand new GPU-accelerated mathematics and data library to your own .NET platform. The supported NVIDIA GPU patterns include a range of compact linear algebra algorithms and 1D and 2D Fast Fourier Transforms (FFTs). NMath Premium is made to be a close drop-in substitute for NMath; there are a couple of essential differences and added logging capabilities that are particular to the superior product.
Modern FFT implementations are hybridized algorithms that change between algorithmic processing and approaches kernels based on the hardware, FFT kind, and FFT length. An FFT library can use the right Cooly-Tukey algorithm for a brief power-of-two FFT but change to Bluestein's algorithm to get odd-length FFT's. Further, based on the FFT span variables, different mixtures of processing kernels might be used. In other words, there's not any single FFT algorithm', so there's not any effortless expression for FLOPS finished per FFT computed. This comparative performance is documented here. For example, if we examine 10 GFLOP's performance to get a specific FFT, which means if you conducted the implementation of this Cooly-Tukey algorithm, you would require a 10 GFLOP's competent machine to coincide with the functionality (complete as fast ).
Since GPU computation occurs at another memory space from the CPU, all information must be replicated to the GPU, and the outcomes then replicated back into the CPU. This backup time overhead is contained in all reported performance numbers. We now include this backup time to provide our library users a precise image of conceivable performance.
The NMath Premium 1D and 2D FFT library has been tested on four distinct NVIDIA GPU's and a 4-core 2.0Ghz Intel i7. These models represent the present selection of functionality available from NVIDIA, ranging from the installed GeForce GTX 525 into NVIDIA's fasted dual precision GPU, the Tesla K20.
The four graphs below represent various power-of-two span, complex to complicated forwards 1D and 2D FFT's. Each of NMath products also easily calculates non-power-of-two span FFT's, but their functionality isn't a part of the GPU comparison notice.
The functioning of the CPU-bound 1D FFT outperformed all the GPU's for comparatively brief FFT lengths. This is anticipated because the GPU's exceptional performance can't be appreciated as a result of data transfer overhead. When the computational complexity of this 1D FFT is large enough, the economic parallel nature outweighs the information transfer overhead, and they begin to overtake the CPU-bound 1D FFT's. This cross-over point happens when the FFT reaches a span near 65536. The exception is that the consumer degree GeForce GTX 525, in which the GPU and CPU FFT performance monitor each other.
The 2D FFT instance differs due to the greater computational requirement of this two-dimensional case. First, in the sole precision instance, we view the inferiority of the NVIDIA K20, which can be made primarily as a double-precision computation engine. Here the CPU-bound outperforms the K20 for all image dimensions. No matter how the K10 and 2090 are very fast (such as the data transfer period ) and outperform the CPU-bound 2D FFT by roughly 60-70%. From the dual precision 2D FFT instance, the K20 outperforms the other chips in nearly all instances quantified. The analyzed K20 was memory restricted from the [ 8192 x 8192 ] test situation and could not finish the computation.
To amortize the cost of information transfer to and from the GPU, NMath Premium can operate FFT's in batches of sign arrays. For the smaller FFT sizes, the batch processing almost doubles the FFT performance on the GPU. Since the FFT period raises the benefit of batch processing diminished because the complete range signals can no longer be loaded in the GPU.
The complexity of the FFT raises either because of a rise in span or difficulty size. The GPU leveraged FFT performance overtakes the CPU-bound edition. The benefit of this GPU 1D FFT increases considerably since the FFT span grows past ~100,000 samples. Batch processing of signs organized in rows in a matrix may be utilized to mitigate the GPU's information transfer overhead. There are occasions at which it could be advantageous to ditch FFT's processing on the GPU even if CPU-bound functionality is higher because this can free many CPU cycles for different pursuits. Since NMath Premium supports flexible crossover thresholds, the programmer can control the FFT span where FFT computation switches into the GPU. Putting this threshold to zero may drive all FFT processing on the GPU, fully offloading this work from the CPU.
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