bench_cpu_kswapd_anon_rand.cc

#include <iostream>
#include <stdlib.h>
#include <sys/mman.h>
#include <string.h>
#include <errno.h>
#include <stdint.h>

#include <cstdlib>
#include <ctime>

#include "rdmemusg.h"
#include "pattern.h"
#include "pinning.h"

// returns a random unsigned long with upto 45-bits of pseudo-randomness
unsigned long random_number(unsigned long min, unsigned long max) {
        int rand_hi = rand();
        int rand_mi = rand();
        int rand_lo = rand();
        unsigned long rand_45 = (((unsigned long)rand_hi) << 30) ^ (((unsigned long)rand_mi) << 15) ^ rand_lo;

        return rand_45 % max;
}

int main(int argc, char **argv) {
    set_cpu(0);

	if (argc < 3) {
        std::cout << "Usage: ./prog num_gb kswapd_pid" << std::endl;
		return -1;
	}

	size_t gbs = atoi(argv[1]);
	size_t kswapd = atoi(argv[2]);
    uint64_t vma_size = (uint64_t)gbs << 30;

    char* start_addr = (char*)mmap(NULL, vma_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
    if (start_addr == MAP_FAILED) {
        std::cerr << "mmap failed: " << strerror(errno) << std::endl;
        exit(1);
    }

    unsigned long long num_pages_mapped = vma_size / PAGE_SIZE;
    unsigned long* total_jiffies = (unsigned long*)malloc(num_pages_mapped * sizeof(unsigned long));
    unsigned long* pid_jiffies = (unsigned long*)malloc(num_pages_mapped * sizeof(unsigned long));

    // touch all pages
    for(unsigned long i = 0; i < num_pages_mapped; i++) {
        total_jiffies[i] = 0;
        pid_jiffies[i] = 0;
    }

    // lock this results array itself so itself is not swapped out
    if(mlock((const void*) total_jiffies, num_pages_mapped * sizeof(double))) {
        std::cerr << "mlock failed: " << strerror(errno) << std::endl;
        exit(1);
    }
    if(mlock((const void*) pid_jiffies, num_pages_mapped * sizeof(double))) {
        std::cerr << "mlock failed: " << strerror(errno) << std::endl;
        exit(1);
    }

    // seed the rng
	srand((int)time(0));
    
    // touch all the pages now
    char* addr = start_addr;
    for (unsigned long num_touched = 0; num_touched < num_pages_mapped; num_touched++) {
        *addr = 'X';
        total_jiffies[num_touched] = get_uptime_jiffies();
        pid_jiffies[num_touched] = get_pid_jiffies(kswapd);
        addr = ((char*)start_addr) + random_number(0, vma_size);
        //printf("%lx\n", (unsigned long)addr);
    }

    for (unsigned int i = 0; i < num_pages_mapped; i++) {
        std::cout << total_jiffies[i] << " " << pid_jiffies[i] << std::endl;
    }
}