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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <algorithm>
#include <vector>
#include <errno.h>
#include <cassert>
// iobench -seq -write 1024 - sequentially write 1024MB to /tmp/iobench.dat
// iobench -rand -write 1024 - sequentially write 1024MB (in 256K chunks) to
// /tmp/iobench.dat
// iobench -seq -read 1024 - sequentially read 1024MB from /tmp/iobench.dat
// iobench -rand -read 1024 - sequentially read 1024MB (in 256K chunks) from
// /tmp/iobench.dat
#ifdef __ANDROID__
#define TMP_DIR "/data/local/tmp"
#else // __linux__
#define TMP_DIR "/tmp"
#endif
#define DATA_FILE TMP_DIR "/iobench.dat"
// Allocate a buffer of size |buffer_size|. Fill it with
// non-zero data to prevent sparse files from being created
void* mallocNoise(size_t buffer_size) {
void* result = malloc(buffer_size);
for (int i = 0; i < buffer_size; i += 512) {
int* block = (int*)((char*)result + i);
*block = i + 1;
}
return result;
}
// We want to test random file access but we want to make sure that
// every read/write chunk is read/written exactly once.
// So we make a sequential list of chunk indexes and shuffle it
std::vector<size_t> createRandomChunkList(size_t chunk_count) {
std::random_device rd;
std::mt19937 gen(rd());
std::uniform_int_distribution<size_t> dist(0, chunk_count-1);
std::vector<size_t> result(chunk_count);
// a sequential list of chunk indexes
for (int64_t i = 0; i < chunk_count; i++) {
result[i] = i;
}
// shuffle the list of chunk indexes
// swap every chunk with a random chunk
std::shuffle(result.begin(), result.end(), gen);
return result;
}
const int NS_PER_SEC = 1000 * 1000 * 1000;
int64_t subtractTimespec(const struct timespec* hi, const struct timespec* lo) {
int64_t delta = hi->tv_sec - lo->tv_sec;
delta *= NS_PER_SEC;
delta += hi->tv_nsec;
delta -= lo->tv_nsec;
return delta;
}
int main(int argc, const char* argv[]) {
const size_t kBufferSize = 256 * 1024;
bool read_mode = false;
size_t chunk_size = kBufferSize;
bool rand_mode = false;
size_t file_size_mb = 1024;
for (int i = 1; i < argc; i++) {
if (strcmp("-rand", argv[i]) == 0) {
rand_mode = true;
chunk_size = 4 * 1024;
} else if (strcmp("-seq", argv[i]) == 0) {
rand_mode = false;
chunk_size = kBufferSize;
} else if (strcmp("-read", argv[i]) == 0) {
read_mode = true;
} else if (strcmp("-write", argv[i]) == 0) {
read_mode = false;
} else {
file_size_mb = strtoul(argv[i], nullptr, 10);
}
}
size_t file_size = file_size_mb * 1024 * 1024;
size_t chunk_count = file_size / chunk_size;
std::vector<size_t> chunk_list = createRandomChunkList(chunk_count);
int open_flags = O_CREAT;
if (read_mode) {
open_flags |= O_RDONLY;
} else {
open_flags |= O_WRONLY;
}
int fd = open(DATA_FILE, open_flags, 0600);
if (fd < 0) {
perror("open");
return -1;
}
void* buffer = mallocNoise(kBufferSize);
struct timespec start;
if (clock_gettime(CLOCK_REALTIME, &start) < 0) {
perror("clock_gettime");
return -1;
}
for (int i = 0; i < chunk_count; i++) {
if (rand_mode) {
off64_t off = chunk_list[i] * chunk_size;
off64_t result = lseek64(fd, off, SEEK_SET);
if (result != off) {
perror("lseek64");
return -1;
}
}
if (read_mode) {
ssize_t read_result = read(fd, buffer, chunk_size);
if (chunk_size != read_result) {
perror("read");
return -1;
}
} else {
if (chunk_size != write(fd, buffer, chunk_size)) {
perror("write");
return -1;
}
}
}
if (!read_mode) {
if (fsync(fd) < 0) {
perror("fsync");
return -1;
}
}
if (close(fd) < 0) {
perror("close");
return -1;
}
struct timespec end;
if (clock_gettime(CLOCK_REALTIME, &end) < 0) {
perror("clock_gettime");
return -1;
}
int64_t elapsed_ns = subtractTimespec(&end, &start);
#ifdef DEBUG
printf("start sec %li nsec %li\n", start.tv_sec, start.tv_nsec);
printf("end sec %li nsec %li\n", end.tv_sec, end.tv_nsec);
printf("megabytes: %zu\n", file_size_mb);
printf("time elapsed: %lins\n", elapsed_ns);
printf("time elapsed: %fs\n", (double)elapsed_ns / (double)NS_PER_SEC);
#endif
if (elapsed_ns > 0) {
double megabytes_per_second =
(double) file_size_mb * (double) NS_PER_SEC / (double) elapsed_ns;
printf("%.2fMB/s\n", megabytes_per_second);
}
else {
printf("elapsed_ns == 0\n");
}
return 0;
}
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