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#include <string>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <iostream>
#include <vector>
#include <tuple>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
using namespace std;
static const size_t pageSize = 4096;
class Fd {
int m_fd = -1;
public:
int get() { return m_fd; }
void set(int fd) { m_fd = fd; }
Fd() {}
Fd(int fd) : m_fd{fd} {}
~Fd() {
if (m_fd >= 0)
close(m_fd);
}
};
int dummy = 0;
void fillPageJunk(void *ptr)
{
uint64_t seed = (unsigned long long)rand() | ((unsigned long long)rand() << 32);
uint64_t *target = (uint64_t*)ptr;
for (int i = 0; i < pageSize / sizeof(uint64_t); i++) {
*target = seed ^ (uint64_t)(uintptr_t)target;
seed = (seed << 1) | ((seed >> 63) & 1);
target++;
}
}
class FileMap {
string m_name;
size_t m_size;
void *m_ptr = nullptr;
Fd m_fileFd;
public:
enum Hint {
FILE_MAP_HINT_NONE,
FILE_MAP_HINT_RAND,
FILE_MAP_HINT_LINEAR,
};
FileMap(const string &name, size_t size, Hint hint = FILE_MAP_HINT_NONE) : m_name{name}, m_size{size} {
int fd = open(name.c_str(), O_CREAT | O_RDWR, S_IRWXU);
if (fd < 0) {
cerr << "open failed: " << fd << endl;
return;
}
m_fileFd.set(fd);
fallocate(m_fileFd.get(), 0, 0, size);
unlink(name.c_str());
m_ptr = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED, m_fileFd.get(), 0);
if ((int)(uintptr_t)m_ptr == -1) {
cerr << "mmap failed: " << (int)(uintptr_t)m_ptr << endl;
m_ptr = nullptr;
return;
}
switch (hint) {
case FILE_MAP_HINT_NONE: break;
case FILE_MAP_HINT_RAND:
madvise(m_ptr, m_size, MADV_RANDOM);
break;
case FILE_MAP_HINT_LINEAR:
madvise(m_ptr, m_size, MADV_SEQUENTIAL);
break;
}
for (int i = 0; i < m_size / pageSize; i++) {
uint8_t *targetPtr = (uint8_t*)m_ptr + 4096ull * i;
fillPageJunk(targetPtr);
}
}
void benchRandom(bool write) {
size_t pagesTotal = m_size / pageSize;
size_t pagesToHit = pagesTotal / 128;
uint64_t nsTotal = 0;
chrono::time_point<chrono::high_resolution_clock> start, end;
start = chrono::high_resolution_clock::now();
for (int j = 0; j < pagesToHit; j++) {
int targetPage = rand() % pagesTotal;
uint8_t *targetPtr = (uint8_t*)m_ptr + 4096ull * targetPage;
if (write) {
*targetPtr = dummy;
}
else {
dummy += *targetPtr;
}
}
end = chrono::high_resolution_clock::now();
nsTotal += chrono::duration_cast<chrono::nanoseconds>(end - start).count();
//cout << "random: " << nsTotal / 1000.0 / (pagesToHit) << "us/page" << endl;
cout << "random " << (write ? "write" : "read") << ": " << ((4096.0 * pagesToHit) / (1 << 20)) / (nsTotal / 1.0E9) << "MB/s" << endl;
}
void benchLinear(bool write) {
int pagesTotal = m_size / pageSize;
int iterations = 4;
uint64_t nsTotal = 0;
chrono::time_point<chrono::high_resolution_clock> start, end;
start = chrono::high_resolution_clock::now();
for (int i = 0; i < iterations; i++) {
for (int j = 0; j < pagesTotal; j++) {
uint8_t *targetPtr = (uint8_t*)m_ptr + 4096ull * j;
if (write) {
*targetPtr = dummy;
}
else {
dummy += *targetPtr;
}
}
}
end = chrono::high_resolution_clock::now();
nsTotal += chrono::duration_cast<chrono::nanoseconds>(end - start).count();
//cout << "linear: " << nsTotal / 1000.0 / (pagesTotal * iterations) << "us/page" << endl;
cout << "linear " << (write ? "write" : "read") << ": " << ((4096.0 * pagesTotal * iterations) / (1 << 20)) / (nsTotal / 1.0E9 ) << "MB/s" << endl;
}
void dropCache() {
int ret1 = msync(m_ptr, m_size, MS_SYNC | MS_INVALIDATE);
madvise(m_ptr, m_size, MADV_DONTNEED);
(void)ret1;
}
~FileMap() {
if (m_ptr)
munmap(m_ptr, m_size);
}
};
int main(int argc, char *argv[])
{
(void)argc;
(void)argv;
srand(0);
{
FileMap file{"/data/local/tmp/mmap_test", 16000 * (1ull << 20)};
file.benchRandom(false);
}
{
FileMap file{"/data/local/tmp/mmap_test", 16000 * (1ull << 20)};
file.benchLinear(false);
}
{
FileMap file{"/data/local/tmp/mmap_test", 16000 * (1ull << 20)};
file.benchRandom(true);
}
{
FileMap file{"/data/local/tmp/mmap_test", 16000 * (1ull << 20)};
file.benchLinear(true);
}
return 0;
}
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