mem_test.c

#define _GNU_SOURCE
#include <stdio.h>
#include <stdint.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <assert.h>
#include <stdlib.h>

static void enable_perf(int perf_ctl_fd, int perf_ack_fd)
{
    char ack[5];
    if (perf_ctl_fd != -1)
    {
        ssize_t bytes_written = write(perf_ctl_fd, "enable\n", 8);
        printf("bytes_written: %ld\n", bytes_written);
        assert(bytes_written == 8);
    }
    if (perf_ack_fd != -1)
    {
        ssize_t bytes_read = read(perf_ack_fd, ack, 5);
        assert(bytes_read == 5 && strcmp(ack, "ack\n") == 0);
    }
    __asm__ volatile("xchgq %r10, %r10");
}

static void disable_perf(int perf_ctl_fd, int perf_ack_fd)
{
    char ack[5];
    __asm__ volatile("xchgq %r11, %r11");
    if (perf_ctl_fd != -1)
    {
        ssize_t bytes_written = write(perf_ctl_fd, "disable\n", 9);
        assert(bytes_written == 9);
    }

    if (perf_ack_fd != -1)
    {
        ssize_t bytes_read = read(perf_ack_fd, ack, 5);
        assert(bytes_read == 5 && strcmp(ack, "ack\n") == 0);
    }
}

static int get_fifo_fd(const char *fifo_name, int flags)
{
    int fd = open(fifo_name, flags);
    if (fd == -1)
    {
        perror("open");
        exit(EXIT_FAILURE);
    }
    return fd;
}

#define PERF_ARGC 3

int main(int argc, char **argv)
{
    void *addr_start = (void *)0x400000000001;
    size_t len = (1ULL << 25); /* 32MB */
    uint32_t step = 0x1000;

    int perf_ctl_fd = -1;
    int perf_ack_fd = -1;

    if (argc == PERF_ARGC)
    {
        perf_ctl_fd = get_fifo_fd(argv[PERF_ARGC - 2], O_WRONLY);
        perf_ack_fd = get_fifo_fd(argv[PERF_ARGC - 1], O_RDONLY);
    }
    printf("perf_ctl_fd: %d\n", perf_ctl_fd);
    printf("perf_ack_fd: %d\n", perf_ack_fd);

    volatile uint8_t *a = mmap(addr_start, len, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

    if (a == MAP_FAILED)
    {
        perror("mmap failed");
        return 1;
    }
    uint64_t sum = 0;
    printf("n mem refs =%lx\n", len / step);
    printf("a at %llx\n", (unsigned long long)a);

    enable_perf(perf_ctl_fd, perf_ack_fd);

    for (int i = 0; i < len; i += step)
    {
        a[i] = 0;
        if (i % (1ULL << 20) == 0){
            printf("i=%x\n", i);
        }
    }
    for (int i = 0; i < len; i += step)
    {
        uint32_t *p = (uint32_t *)&a[i];
        *p = 64;
        sum += a[i];
    }

    disable_perf(perf_ctl_fd, perf_ack_fd);

    printf("sum=%lx\n", sum);
    return 0;
}