hw.c

Go to the documentation of this file.

/*
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License, version 2 of the
 *   License as published by the Free Software Foundation.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/** Functions for getting information about the system architecture
 *
 * @file src/lib/util/hw.c
 *
 * @author Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 * @copyright 2020 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
 
#define CACHE_LINE_DEFAULT      128
 
/*
 *      fr_hw_num_cores_active() on Linux reports a failure as 0 cores,
 *      and does not use a default.
 */
#ifndef __linux__
#  define CORES_DEFAULT         1
#endif
 
#include <freeradius-devel/util/hw.h>
#include <freeradius-devel/util/syserror.h>
#include <freeradius-devel/util/strerror.h>
 
#if defined(__APPLE__) || defined(__FreeBSD__)
#include <sys/sysctl.h>
size_t fr_hw_cache_line_size(void)
{
        size_t cache_line_size          = CACHE_LINE_DEFAULT;
        size_t cache_line_size_len      = sizeof(cache_line_size);
 
        sysctlbyname("hw.cachelinesize", &cache_line_size, &cache_line_size_len, 0, 0);
 
        return cache_line_size;
}
 
uint32_t fr_hw_num_cores_active(void)
{
        uint32_t num_cores              = CORES_DEFAULT;
        size_t num_cores_len            = sizeof(num_cores);
 
        sysctlbyname("hw.physicalcpu", &num_cores, &num_cores_len, 0, 0);
 
        return num_cores;
}
 
#elif defined(__linux__)
#include <stdio.h>
#include <unistd.h>
size_t fr_hw_cache_line_size(void)
{
        FILE *file                      = NULL;
        unsigned int cache_line_size    = CACHE_LINE_DEFAULT;
 
        file = fopen("/sys/devices/system/cpu/cpu0/cache/index0/coherency_cache_line_size", "r");
        if (file) {
                if (fscanf(file, "%u", &cache_line_size) != 1) {
                        cache_line_size = CACHE_LINE_DEFAULT;
                }
                fclose(file);
        }
 
        return cache_line_size;
}
 
uint32_t fr_hw_num_cores_active(void)
{
        uint32_t lcores = 0, tsibs = 0;
 
        char buff[32];
        char path[64];
 
        for (lcores = 0;;lcores++) {
                FILE *cpu;
 
                snprintf(path, sizeof(path), "/sys/devices/system/cpu/cpu%u/topology/thread_siblings_list", lcores);
 
                cpu = fopen(path, "r");
                if (!cpu) break;
 
                /*
                 *      Each number is a sibling.  EOF is non-zero, so a
                 *      test against zero does not stop at the end of the
                 *      file.  Test for the one requested conversion.
                 */
                while (fscanf(cpu, "%31[0-9]", buff) == 1) {
                        tsibs++;
                        if (fgetc(cpu) != ',') break;
                }
 
                fclose(cpu);
        }
 
        /*
         *      Catch Linux weirdness.
         *
         *      You'd think this would be enough to quiet clang scan,
         *      but it's not.
         */
        if (unlikely((tsibs == 0) || (lcores == 0) || (lcores > tsibs))) {
                fr_strerror_printf("Failed retrieving cpu topology info: %s", fr_syserror(errno));
                return 0;
        }
 
#ifdef STATIC_ANALYZER
        /*
         *      Prevent static analyzer from warning about divide by zero
         */
        if ((tsibs / lcores) == 0) return 0;
#endif
 
        return lcores / (tsibs / lcores);
}
#else
size_t fr_hw_cache_line_size(void)
{
        return CACHE_LINE_DEFAULT;
}
 
uint32_t fr_hw_num_cores_active(void)
{
        return CORES_DEFAULT;
}
#endif