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psblas3/cuda/spgpu/kernels/dnrm2.cu

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/*
* spGPU - Sparse matrices on GPU library.
*
* Copyright (C) 2010 - 2012
* Davide Barbieri - University of Rome Tor Vergata
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 3 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include "stdio.h"
#include "cudalang.h"
#include "cudadebug.h"
extern "C"
{
#include "core.h"
#include "vector.h"
}
//#define USE_CUBLAS
//#define ASSUME_LOCK_SYNC_PARALLELISM
#define BLOCK_SIZE 512
static __device__ double dnrm2ReductionResult[128];
__global__ void spgpuDnrm2_kern(int n, double* x)
{
__shared__ double sSum[BLOCK_SIZE];
double res = 0;
double* lastX = x + n;
x += threadIdx.x + blockIdx.x*BLOCK_SIZE;
int blockOffset = gridDim.x*BLOCK_SIZE;
while (x < lastX)
{
double x1 = x[0];
res = PREC_DADD(res, PREC_DMUL(x1, x1));
x += blockOffset;
}
if (threadIdx.x >= 32)
sSum[threadIdx.x] = res;
__syncthreads();
// Start reduction!
if (threadIdx.x < 32)
{
for (int i=1; i<BLOCK_SIZE/32; ++i)
{
res += sSum[i*32 + threadIdx.x];
}
//useless (because inter-warp)
#ifndef ASSUME_LOCK_SYNC_PARALLELISM
}
__syncthreads();
if (threadIdx.x < 32)
{
#endif
#ifdef ASSUME_LOCK_SYNC_PARALLELISM
volatile double* vsSum = sSum;
vsSum[threadIdx.x] = res;
if (threadIdx.x < 16) vsSum[threadIdx.x] += vsSum[threadIdx.x + 16];
if (threadIdx.x < 8) vsSum[threadIdx.x] += vsSum[threadIdx.x + 8];
if (threadIdx.x < 4) vsSum[threadIdx.x] += vsSum[threadIdx.x + 4];
if (threadIdx.x < 2) vsSum[threadIdx.x] += vsSum[threadIdx.x + 2];
if (threadIdx.x == 0)
dnrm2ReductionResult[blockIdx.x] = vsSum[0] + vsSum[1];
#else
double* vsSum = sSum;
vsSum[threadIdx.x] = res;
if (threadIdx.x < 16) vsSum[threadIdx.x] += vsSum[threadIdx.x + 16];
__syncthreads();
if (threadIdx.x < 8) vsSum[threadIdx.x] += vsSum[threadIdx.x + 8];
__syncthreads();
if (threadIdx.x < 4) vsSum[threadIdx.x] += vsSum[threadIdx.x + 4];
__syncthreads();
if (threadIdx.x < 2) vsSum[threadIdx.x] += vsSum[threadIdx.x + 2];
__syncthreads();
if (threadIdx.x == 0)
dnrm2ReductionResult[blockIdx.x] = vsSum[0] + vsSum[1];
#endif
}
}
double spgpuDnrm2(spgpuHandle_t handle, int n, double* x)
{
#ifdef USE_CUBLAS
double res;
cublasDnrm2(n,x,1,&res);
cudaDeviceSynchronize();
return res;
#else
double res = 0;
#if 0
int device;
cudaGetDevice(&device);
struct cudaDeviceProp prop;
cudaGetDeviceProperties(&prop,device);
int blocks = min(128, min(prop.multiProcessorCount, (n+BLOCK_SIZE-1)/BLOCK_SIZE));
#else
int blocks = min(128, min(handle->multiProcessorCount, (n+BLOCK_SIZE-1)/BLOCK_SIZE));
#endif
double tRes[128];
spgpuDnrm2_kern<<<blocks, BLOCK_SIZE, 0, handle->currentStream>>>(n, x);;
cudaMemcpyFromSymbol(tRes, dnrm2ReductionResult,blocks*sizeof(double));
for (int i=0; i<blocks; ++i)
{
res += tRes[i];
}
cudaCheckError("CUDA error on dnrm2");
return sqrt(res);
#endif
}
void spgpuDmnrm2(spgpuHandle_t handle, double *y, int n, __device double *x, int count, int pitch)
{
for (int i=0; i < count; ++i)
{
y[i] = spgpuDnrm2(handle, n, x);
x += pitch;
}
}