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/* Copyright (c) 2022, NVIDIA CORPORATION. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of NVIDIA CORPORATION nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <cooperative_groups.h>
namespace cg = cooperative_groups;
#include <helper_cuda.h>
#include "histogram_common.h"
////////////////////////////////////////////////////////////////////////////////
// Shortcut shared memory atomic addition functions
////////////////////////////////////////////////////////////////////////////////
#define TAG_MASK 0xFFFFFFFFU
inline __device__ void addByte(uint *s_WarpHist, uint data, uint threadTag) {
atomicAdd(s_WarpHist + data, 1);
}
inline __device__ void addWord(uint *s_WarpHist, uint data, uint tag) {
addByte(s_WarpHist, (data >> 0) & 0xFFU, tag);
addByte(s_WarpHist, (data >> 8) & 0xFFU, tag);
addByte(s_WarpHist, (data >> 16) & 0xFFU, tag);
addByte(s_WarpHist, (data >> 24) & 0xFFU, tag);
}
__global__ void histogram256Kernel(uint *d_PartialHistograms, uint *d_Data,
uint dataCount) {
// Handle to thread block group
cg::thread_block cta = cg::this_thread_block();
// Per-warp subhistogram storage
__shared__ uint s_Hist[HISTOGRAM256_THREADBLOCK_MEMORY];
uint *s_WarpHist =
s_Hist + (threadIdx.x >> LOG2_WARP_SIZE) * HISTOGRAM256_BIN_COUNT;
// Clear shared memory storage for current threadblock before processing
#pragma unroll
for (uint i = 0;
i < (HISTOGRAM256_THREADBLOCK_MEMORY / HISTOGRAM256_THREADBLOCK_SIZE);
i++) {
s_Hist[threadIdx.x + i * HISTOGRAM256_THREADBLOCK_SIZE] = 0;
}
// Cycle through the entire data set, update subhistograms for each warp
const uint tag = threadIdx.x << (UINT_BITS - LOG2_WARP_SIZE);
cg::sync(cta);
for (uint pos = UMAD(blockIdx.x, blockDim.x, threadIdx.x); pos < dataCount;
pos += UMUL(blockDim.x, gridDim.x)) {
uint data = d_Data[pos];
addWord(s_WarpHist, data, tag);
}
// Merge per-warp histograms into per-block and write to global memory
cg::sync(cta);
for (uint bin = threadIdx.x; bin < HISTOGRAM256_BIN_COUNT;
bin += HISTOGRAM256_THREADBLOCK_SIZE) {
uint sum = 0;
for (uint i = 0; i < WARP_COUNT; i++) {
sum += s_Hist[bin + i * HISTOGRAM256_BIN_COUNT] & TAG_MASK;
}
d_PartialHistograms[blockIdx.x * HISTOGRAM256_BIN_COUNT + bin] = sum;
}
}
////////////////////////////////////////////////////////////////////////////////
// Merge histogram256() output
// Run one threadblock per bin; each threadblock adds up the same bin counter
// from every partial histogram. Reads are uncoalesced, but mergeHistogram256
// takes only a fraction of total processing time
////////////////////////////////////////////////////////////////////////////////
#define MERGE_THREADBLOCK_SIZE 256
__global__ void mergeHistogram256Kernel(uint *d_Histogram,
uint *d_PartialHistograms,
uint histogramCount) {
// Handle to thread block group
cg::thread_block cta = cg::this_thread_block();
uint sum = 0;
for (uint i = threadIdx.x; i < histogramCount; i += MERGE_THREADBLOCK_SIZE) {
sum += d_PartialHistograms[blockIdx.x + i * HISTOGRAM256_BIN_COUNT];
}
__shared__ uint data[MERGE_THREADBLOCK_SIZE];
data[threadIdx.x] = sum;
for (uint stride = MERGE_THREADBLOCK_SIZE / 2; stride > 0; stride >>= 1) {
cg::sync(cta);
if (threadIdx.x < stride) {
data[threadIdx.x] += data[threadIdx.x + stride];
}
}
if (threadIdx.x == 0) {
d_Histogram[blockIdx.x] = data[0];
}
}
////////////////////////////////////////////////////////////////////////////////
// Host interface to GPU histogram
////////////////////////////////////////////////////////////////////////////////
// histogram256kernel() intermediate results buffer
static const uint PARTIAL_HISTOGRAM256_COUNT = 240;
static uint *d_PartialHistograms;
// Internal memory allocation
extern "C" void initHistogram256(void) {
checkCudaErrors(cudaMalloc(
(void **)&d_PartialHistograms,
PARTIAL_HISTOGRAM256_COUNT * HISTOGRAM256_BIN_COUNT * sizeof(uint)));
}
// Internal memory deallocation
extern "C" void closeHistogram256(void) {
checkCudaErrors(cudaFree(d_PartialHistograms));
}
extern "C" void histogram256(uint *d_Histogram, void *d_Data, uint byteCount) {
assert(byteCount % sizeof(uint) == 0);
histogram256Kernel<<<PARTIAL_HISTOGRAM256_COUNT,
HISTOGRAM256_THREADBLOCK_SIZE>>>(
d_PartialHistograms, (uint *)d_Data, byteCount / sizeof(uint));
getLastCudaError("histogram256Kernel() execution failed\n");
mergeHistogram256Kernel<<<HISTOGRAM256_BIN_COUNT, MERGE_THREADBLOCK_SIZE>>>(
d_Histogram, d_PartialHistograms, PARTIAL_HISTOGRAM256_COUNT);
getLastCudaError("mergeHistogram256Kernel() execution failed\n");
}
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