Introduction to cuda geek camp singapore 2011

INTRODUCTION TO CUDAPrepared for Geek Camp Singapore 2011 Raymond Tay

THE FREE LUNCH IS OVER – HERBSUTTER

WE NEED TO THINK BEYOND MULTI-CORECPUS … WE NEED TO THINK MANY-COREGPUS…

NVIDIA GPUS FPS  FPS – Floating-point per second aka flops. A measure of how many flops can a GPU do. More is Better  GPUs beat CPUs

NVIDIA GPUS MEMORY BANDWIDTH  With massively parallel processors in Nvidia’s GPUs, providing high memory bandwidth plays a big role in high performance computing. GPUs beat CPUs

GPU VS CPUCPU GPU"   Optimised for low-latency "   Optimised for data-parallel, access to cached data sets throughput computation"   Control logic for out-of-order "   Architecture tolerant of and speculative execution memory latency "   More transistors dedicated to computation

I DON’T KNOW C/C++, SHOULD I LEAVE? Your Brain Asks: Wait a minute, why  Relax, no worries. Not to fret. should I learn the C/ C++ SDK? CUDA Answers: Efficiency!!!

WHAT DO I NEED TO BEGIN WITH CUDA?  A Nvidia CUDA enabled graphics card e.g. Fermi

HOW DOES CUDA WORK PCI Bus1.  Copy input data from CPU memory to GPU memory2.  Load GPU program and execute, caching data on chip for performance3.  Copy results from GPU memory to CPU memory

EXAMPLE: BLOCK CYPHERvoid host_shift_cypher(unsigned int *input_array, __global__ void shift_cypher(unsigned int unsigned int *output_array, unsigned int *input_array, unsigned int *output_array, shift_amount, unsigned int alphabet_max, unsigned int shift_amount, unsigned int unsigned int array_length) alphabet_max, unsigned int array_length) { { for(unsigned int i=0;i<array_length;i++) unsigned int tid = threadIdx.x + blockIdx.x * { blockDim.x; int element = input_array[i]; int shifted = input_array[tid] + shift_amount; int shifted = element + shift_amount; if ( shifted > alphabet_max ) if(shifted > alphabet_max) shifted = shifted % (alphabet_max + 1); { shifted = shifted % (alphabet_max + 1); output_array[tid] = shifted; } } output_array[i] = shifted; } Int main() { } dim3 dimGrid(ceil(array_length)/block_size); Int main() { dim3 dimBlock(block_size); host_shift_cypher(input_array, output_array, shift_cypher<<<dimGrid,dimBlock>>>(input_array, shift_amount, alphabet_max, array_length); output_array, shift_amount, alphabet_max,} array_length); } CPU GPU Program Program

EXAMPLE: VECTOR ADDITION // CUDA CODE__global__ void VecAdd(const float* A, const float* B, float* C, unsigned int N){ int i = blockDim.x * blockIdx.x + threadIdx.x; if (i < N) C[i] = A[i] + B[i];}// C CODEvoid VecAdd(const float* A, const float* B, float* C,unsigned int N){ for( int i = 0; i < N; ++i) C[i] = A[i] + B[i];}

DEBUGGER CUDA-GDB • Based on GDB • Linux • Mac OS X Parallel Nsight • Plugin inside Visual Studio

VISUAL PROFILER & MEMCHECK Profiler •  Microsoft Windows •  Linux •  Mac OS X •  Analyze Performance CUDA-MEMCHECK •  Microsoft Windows •  Linux •  Mac OS X •  Detect memory access errors

WHERE’S CUDA AT IN 2011?  60,000 researchers use it to aid drug discovery  470 universities teach CUDA

WHERE’S CUDA AT IN 2011? (PART 2..)  NVIDIA Show Case (1000+ applications)

ADDITIONAL RESOURCES  CUDA FAQ (http://tegradeveloper.nvidia.com/cuda-faq)  CUDA Tools & Ecosystem ( http://tegradeveloper.nvidia.com/cuda-tools-ecosystem)  CUDA Downloads (http://tegradeveloper.nvidia.com/cuda-downloads)  NVIDIA Forums (http://forums.nvidia.com/index.php?showforum=62)  GPGPU (http://gpgpu.org )  CUDA By Example ( http://tegradeveloper.nvidia.com/content/cuda-example-introduction- general-purpose-gpu-programming-0)   Jason Sanders & Edward Kandrot  GPU Computing Gems Emerald Edition ( http://www.amazon.com/GPU-Computing-Gems-Emerald-Applications/dp/ 0123849888/ )   Editor in Chief: Prof Hwu Wen-Mei

CUDA LIBRARIES  Visit this site http://developer.nvidia.com/cuda-tools- ecosystem#Libraries  Thrust, CUFFT, CUBLAS, CUSP, NPP, OpenCV, GPU AI-Tree Search, GPU AI-Path Finding  A lot of the libraries are hosted in Google Code. Many more gems in there too!

THANK YOU @RaymondTayBL

Introduction to cuda geek camp singapore 2011

by Raymond Tay on Oct 01, 2011

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Introduction to cuda geek camp singapore 2011 — Presentation Transcript

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