affinity.cpp

/*
    -- MAGMA (version 2.1.0) --
       Univ. of Tennessee, Knoxville
       Univ. of California, Berkeley
       Univ. of Colorado, Denver
       @date August 2016

       @author Raffaele Solca

*/
#ifndef MAGMA_NOAFFINITY

#include "affinity.h"

#include <stdio.h>

affinity_set::affinity_set()
{
    CPU_ZERO(&set);
}


affinity_set::affinity_set(int cpu)
{
    CPU_ZERO(&set);
    CPU_SET(cpu, &set);
}


void affinity_set::add(int cpu)
{
    CPU_SET(cpu, &set);
}


int affinity_set::get_affinity()
{
    return sched_getaffinity( 0, sizeof(set), &set);
}


int affinity_set::set_affinity()
{
    return sched_setaffinity( 0, sizeof(set), &set);
}


void affinity_set::print_affinity(int id, const char* s)
{
    if (get_affinity() == 0)
        print_set(id, s);
    else
        printf("Error in sched_getaffinity\n");
}


void affinity_set::print_set(int id, const char* s)
{
// CPU_COUNT() first appeared in glibc 2.6.
#if __GLIBC_PREREQ(2,6)
    char cpustring[1024];

    int cpu_count = CPU_COUNT(&set);
    int charcnt = 0;

    charcnt = snprintf( cpustring, sizeof(cpustring), "thread %d has affinity with %d CPUS: ", id, cpu_count);

    int nrcpu = 0;

    for (int icpu=0; nrcpu < cpu_count && icpu < CPU_SETSIZE; ++icpu) {
        if ( CPU_ISSET( icpu, &set )) {
            charcnt += snprintf( &(cpustring[charcnt]), sizeof(cpustring)-charcnt, "%d,", icpu );
            ++nrcpu;
        }
    }
    // charcnt-1 is used to remove "," after last cpu.
    charcnt += snprintf( &(cpustring[charcnt-1]), sizeof(cpustring)-(charcnt-1), "\n" ) - 1;
    printf("%s: %s", s, cpustring);
    fflush(stdout);
#endif
}

#endif  // MAGMA_NOAFFINITY