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// SPDX-License-Identifier: GPL-2.0-only
/*
* (C) 2004-2009 Dominik Brodowski <linux@dominikbrodowski.de>
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include "cpupower.h"
#include "cpupower_intern.h"
unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen)
{
ssize_t numread;
int fd;
fd = open(path, O_RDONLY);
if (fd == -1)
return 0;
numread = read(fd, buf, buflen - 1);
if (numread < 1) {
close(fd);
return 0;
}
buf[numread] = '\0';
close(fd);
return (unsigned int) numread;
}
unsigned int cpupower_write_sysfs(const char *path, char *buf, size_t buflen)
{
ssize_t numwritten;
int fd;
fd = open(path, O_WRONLY);
if (fd == -1)
return 0;
numwritten = write(fd, buf, buflen - 1);
if (numwritten < 1) {
perror(path);
close(fd);
return -1;
}
close(fd);
return (unsigned int) numwritten;
}
/*
* Detect whether a CPU is online
*
* Returns:
* 1 -> if CPU is online
* 0 -> if CPU is offline
* negative errno values in error case
*/
int cpupower_is_cpu_online(unsigned int cpu)
{
char path[SYSFS_PATH_MAX];
int fd;
ssize_t numread;
unsigned long long value;
char linebuf[MAX_LINE_LEN];
char *endp;
struct stat statbuf;
snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu);
if (stat(path, &statbuf) != 0)
return 0;
/*
* kernel without CONFIG_HOTPLUG_CPU
* -> cpuX directory exists, but not cpuX/online file
*/
snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu);
if (stat(path, &statbuf) != 0)
return 1;
fd = open(path, O_RDONLY);
if (fd == -1)
return -errno;
numread = read(fd, linebuf, MAX_LINE_LEN - 1);
if (numread < 1) {
close(fd);
return -EIO;
}
linebuf[numread] = '\0';
close(fd);
value = strtoull(linebuf, &endp, 0);
if (value > 1)
return -EINVAL;
return value;
}
/* returns -1 on failure, 0 on success */
static int sysfs_topology_read_file(unsigned int cpu, const char *fname, int *result)
{
char linebuf[MAX_LINE_LEN];
char *endp;
char path[SYSFS_PATH_MAX];
snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/topology/%s",
cpu, fname);
if (cpupower_read_sysfs(path, linebuf, MAX_LINE_LEN) == 0)
return -1;
*result = strtol(linebuf, &endp, 0);
if (endp == linebuf || errno == ERANGE)
return -1;
return 0;
}
static int __compare(const void *t1, const void *t2)
{
struct cpuid_core_info *top1 = (struct cpuid_core_info *)t1;
struct cpuid_core_info *top2 = (struct cpuid_core_info *)t2;
if (top1->pkg < top2->pkg)
return -1;
else if (top1->pkg > top2->pkg)
return 1;
else if (top1->core < top2->core)
return -1;
else if (top1->core > top2->core)
return 1;
else if (top1->cpu < top2->cpu)
return -1;
else if (top1->cpu > top2->cpu)
return 1;
else
return 0;
}
/*
* Returns amount of cpus, negative on error, cpu_top must be
* passed to cpu_topology_release to free resources
*
* Array is sorted after ->pkg, ->core, then ->cpu
*/
int get_cpu_topology(struct cpupower_topology *cpu_top)
{
int cpu, last_pkg, cpus = sysconf(_SC_NPROCESSORS_CONF);
cpu_top->core_info = malloc(sizeof(struct cpuid_core_info) * cpus);
if (cpu_top->core_info == NULL)
return -ENOMEM;
cpu_top->pkgs = cpu_top->cores = 0;
for (cpu = 0; cpu < cpus; cpu++) {
cpu_top->core_info[cpu].cpu = cpu;
cpu_top->core_info[cpu].is_online = cpupower_is_cpu_online(cpu);
if(sysfs_topology_read_file(
cpu,
"physical_package_id",
&(cpu_top->core_info[cpu].pkg)) < 0) {
cpu_top->core_info[cpu].pkg = -1;
cpu_top->core_info[cpu].core = -1;
continue;
}
if(sysfs_topology_read_file(
cpu,
"core_id",
&(cpu_top->core_info[cpu].core)) < 0) {
cpu_top->core_info[cpu].pkg = -1;
cpu_top->core_info[cpu].core = -1;
continue;
}
}
qsort(cpu_top->core_info, cpus, sizeof(struct cpuid_core_info),
__compare);
/* Count the number of distinct pkgs values. This works
because the primary sort of the core_info struct was just
done by pkg value. */
last_pkg = cpu_top->core_info[0].pkg;
for(cpu = 1; cpu < cpus; cpu++) {
if (cpu_top->core_info[cpu].pkg != last_pkg &&
cpu_top->core_info[cpu].pkg != -1) {
last_pkg = cpu_top->core_info[cpu].pkg;
cpu_top->pkgs++;
}
}
if (!(cpu_top->core_info[0].pkg == -1))
cpu_top->pkgs++;
/* Intel's cores count is not consecutively numbered, there may
* be a core_id of 3, but none of 2. Assume there always is 0
* Get amount of cores by counting duplicates in a package
for (cpu = 0; cpu_top->core_info[cpu].pkg = 0 && cpu < cpus; cpu++) {
if (cpu_top->core_info[cpu].core == 0)
cpu_top->cores++;
*/
return cpus;
}
void cpu_topology_release(struct cpupower_topology cpu_top)
{
free(cpu_top.core_info);
}
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