220 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * (C) 2004-2009 Dominik Brodowski <linux@dominikbrodowski.de>4 */5 6#include <sys/types.h>7#include <sys/stat.h>8#include <fcntl.h>9#include <unistd.h>10#include <stdio.h>11#include <errno.h>12#include <stdlib.h>13 14#include "cpupower.h"15#include "cpupower_intern.h"16 17int is_valid_path(const char *path)18{19 if (access(path, F_OK) == -1)20 return 0;21 return 1;22}23 24unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen)25{26 ssize_t numread;27 int fd;28 29 fd = open(path, O_RDONLY);30 if (fd == -1)31 return 0;32 33 numread = read(fd, buf, buflen - 1);34 if (numread < 1) {35 close(fd);36 return 0;37 }38 39 buf[numread] = '\0';40 close(fd);41 42 return (unsigned int) numread;43}44 45unsigned int cpupower_write_sysfs(const char *path, char *buf, size_t buflen)46{47 ssize_t numwritten;48 int fd;49 50 fd = open(path, O_WRONLY);51 if (fd == -1)52 return 0;53 54 numwritten = write(fd, buf, buflen - 1);55 if (numwritten < 1) {56 perror(path);57 close(fd);58 return -1;59 }60 61 close(fd);62 63 return (unsigned int) numwritten;64}65 66/*67 * Detect whether a CPU is online68 *69 * Returns:70 * 1 -> if CPU is online71 * 0 -> if CPU is offline72 * negative errno values in error case73 */74int cpupower_is_cpu_online(unsigned int cpu)75{76 char path[SYSFS_PATH_MAX];77 int fd;78 ssize_t numread;79 unsigned long long value;80 char linebuf[MAX_LINE_LEN];81 char *endp;82 struct stat statbuf;83 84 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu);85 86 if (stat(path, &statbuf) != 0)87 return 0;88 89 /*90 * kernel without CONFIG_HOTPLUG_CPU91 * -> cpuX directory exists, but not cpuX/online file92 */93 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu);94 if (stat(path, &statbuf) != 0)95 return 1;96 97 fd = open(path, O_RDONLY);98 if (fd == -1)99 return -errno;100 101 numread = read(fd, linebuf, MAX_LINE_LEN - 1);102 if (numread < 1) {103 close(fd);104 return -EIO;105 }106 linebuf[numread] = '\0';107 close(fd);108 109 value = strtoull(linebuf, &endp, 0);110 if (value > 1)111 return -EINVAL;112 113 return value;114}115 116/* returns -1 on failure, 0 on success */117static int sysfs_topology_read_file(unsigned int cpu, const char *fname, int *result)118{119 char linebuf[MAX_LINE_LEN];120 char *endp;121 char path[SYSFS_PATH_MAX];122 123 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/topology/%s",124 cpu, fname);125 if (cpupower_read_sysfs(path, linebuf, MAX_LINE_LEN) == 0)126 return -1;127 *result = strtol(linebuf, &endp, 0);128 if (endp == linebuf || errno == ERANGE)129 return -1;130 return 0;131}132 133static int __compare(const void *t1, const void *t2)134{135 struct cpuid_core_info *top1 = (struct cpuid_core_info *)t1;136 struct cpuid_core_info *top2 = (struct cpuid_core_info *)t2;137 if (top1->pkg < top2->pkg)138 return -1;139 else if (top1->pkg > top2->pkg)140 return 1;141 else if (top1->core < top2->core)142 return -1;143 else if (top1->core > top2->core)144 return 1;145 else if (top1->cpu < top2->cpu)146 return -1;147 else if (top1->cpu > top2->cpu)148 return 1;149 else150 return 0;151}152 153/*154 * Returns amount of cpus, negative on error, cpu_top must be155 * passed to cpu_topology_release to free resources156 *157 * Array is sorted after ->pkg, ->core, then ->cpu158 */159int get_cpu_topology(struct cpupower_topology *cpu_top)160{161 int cpu, last_pkg, cpus = sysconf(_SC_NPROCESSORS_CONF);162 163 cpu_top->core_info = malloc(sizeof(struct cpuid_core_info) * cpus);164 if (cpu_top->core_info == NULL)165 return -ENOMEM;166 cpu_top->pkgs = cpu_top->cores = 0;167 for (cpu = 0; cpu < cpus; cpu++) {168 cpu_top->core_info[cpu].cpu = cpu;169 cpu_top->core_info[cpu].is_online = cpupower_is_cpu_online(cpu);170 if(sysfs_topology_read_file(171 cpu,172 "physical_package_id",173 &(cpu_top->core_info[cpu].pkg)) < 0) {174 cpu_top->core_info[cpu].pkg = -1;175 cpu_top->core_info[cpu].core = -1;176 continue;177 }178 if(sysfs_topology_read_file(179 cpu,180 "core_id",181 &(cpu_top->core_info[cpu].core)) < 0) {182 cpu_top->core_info[cpu].pkg = -1;183 cpu_top->core_info[cpu].core = -1;184 continue;185 }186 }187 188 qsort(cpu_top->core_info, cpus, sizeof(struct cpuid_core_info),189 __compare);190 191 /* Count the number of distinct pkgs values. This works192 because the primary sort of the core_info struct was just193 done by pkg value. */194 last_pkg = cpu_top->core_info[0].pkg;195 for(cpu = 1; cpu < cpus; cpu++) {196 if (cpu_top->core_info[cpu].pkg != last_pkg &&197 cpu_top->core_info[cpu].pkg != -1) {198 199 last_pkg = cpu_top->core_info[cpu].pkg;200 cpu_top->pkgs++;201 }202 }203 if (!(cpu_top->core_info[0].pkg == -1))204 cpu_top->pkgs++;205 206 /* Intel's cores count is not consecutively numbered, there may207 * be a core_id of 3, but none of 2. Assume there always is 0208 * Get amount of cores by counting duplicates in a package209 for (cpu = 0; cpu_top->core_info[cpu].pkg = 0 && cpu < cpus; cpu++) {210 if (cpu_top->core_info[cpu].core == 0)211 cpu_top->cores++;212 */213 return cpus;214}215 216void cpu_topology_release(struct cpupower_topology cpu_top)217{218 free(cpu_top.core_info);219}220