perfCounter.hpp

#ifndef __PERFCOUNTER_HPP__
#define __PERFCOUNTER_HPP__

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/unistd.h>
#include <linux/perf_event.h>
#include <sys/types.h>
#include <sys/syscall.h>
#include <sys/utsname.h>
#include <sys/ioctl.h>
#include <sys/file.h>

static struct perf_event_attr event_attr;
static int* fd;
static int num_fd;

static int perf_event_open(pid_t pid, int cpu, int grp_fd, unsigned long flags)
{
    return syscall(__NR_perf_event_open, &event_attr, pid, cpu, grp_fd, flags);
}

// Initialize and start perf counters (one for each core)
void init_counters(int num_cores)
{
    fd = new int[num_cores];
    num_fd = num_cores;

    /*  http://web.eece.maine.edu/~vweaver/projects/perf_events/perf_event_open.html */
    memset(&event_attr, 0, sizeof(struct perf_event_attr));
	event_attr.type             = PERF_TYPE_HARDWARE;
    event_attr.config           = PERF_COUNT_HW_CACHE_MISSES;
    //event_attr.type             = PERF_TYPE_HW_CACHE;
    //event_attr.config           = PERF_COUNT_HW_CACHE_LL | (PERF_COUNT_HW_CACHE_OP_READ << 8) | (PERF_COUNT_HW_CACHE_RESULT_MISS << 16);
	event_attr.size             = sizeof(struct perf_event_attr);
    event_attr.pinned           = 1;  // Counter should always be on the CPU if at all possible (Osäker på vad denna gör)
	event_attr.disabled         = 0;
    
    for(int i = 0; i < num_cores; i++)
    {
        // pid == -1, cpu >= 0 - Measures all processes/threads on the specified CPU.
        fd[i] = perf_event_open(-1, i, -1, 0);

        if(fd[i] < 0)
            perror("Error opening performance counter");
    }
}

// Reset perf counter for the specified core
void reset_counter(int core_id)
{
    ioctl(fd[core_id], PERF_EVENT_IOC_RESET, 0);
    //ioctl(fd[core_id], PERF_EVENT_IOC_ENABLE, 0);
}

// TODO: unsigned long long might be unnecessary (avoid using unsigned integers)
// Read perf counter for the specified core and return its value
unsigned long long read_counter(int core_id)
{
    unsigned long long rv;
    if(read(fd[core_id], &rv, sizeof(rv)) == 0)
        perror("Error reading performance counter");

    return rv;
}

// Stop all perf counters
void stop_counters()
{
    for(int i = 0; i < num_fd; i++)
    {
        if(close(fd[i]) != 0)
            perror("Error stopping performance counter");
    }
}

#endif