1 // SPDX-License-Identifier: GPL-2.0-only
3 * (C) 2004-2009 Dominik Brodowski <linux@dominikbrodowski.de>
15 #include "cpupower_intern.h"
17 unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen)
22 fd = open(path, O_RDONLY);
26 numread = read(fd, buf, buflen - 1);
35 return (unsigned int) numread;
39 * Detect whether a CPU is online
42 * 1 -> if CPU is online
43 * 0 -> if CPU is offline
44 * negative errno values in error case
46 int cpupower_is_cpu_online(unsigned int cpu)
48 char path[SYSFS_PATH_MAX];
51 unsigned long long value;
52 char linebuf[MAX_LINE_LEN];
56 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu);
58 if (stat(path, &statbuf) != 0)
62 * kernel without CONFIG_HOTPLUG_CPU
63 * -> cpuX directory exists, but not cpuX/online file
65 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu);
66 if (stat(path, &statbuf) != 0)
69 fd = open(path, O_RDONLY);
73 numread = read(fd, linebuf, MAX_LINE_LEN - 1);
78 linebuf[numread] = '\0';
81 value = strtoull(linebuf, &endp, 0);
88 /* returns -1 on failure, 0 on success */
89 static int sysfs_topology_read_file(unsigned int cpu, const char *fname, int *result)
91 char linebuf[MAX_LINE_LEN];
93 char path[SYSFS_PATH_MAX];
95 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/topology/%s",
97 if (cpupower_read_sysfs(path, linebuf, MAX_LINE_LEN) == 0)
99 *result = strtol(linebuf, &endp, 0);
100 if (endp == linebuf || errno == ERANGE)
105 static int __compare(const void *t1, const void *t2)
107 struct cpuid_core_info *top1 = (struct cpuid_core_info *)t1;
108 struct cpuid_core_info *top2 = (struct cpuid_core_info *)t2;
109 if (top1->pkg < top2->pkg)
111 else if (top1->pkg > top2->pkg)
113 else if (top1->core < top2->core)
115 else if (top1->core > top2->core)
117 else if (top1->cpu < top2->cpu)
119 else if (top1->cpu > top2->cpu)
126 * Returns amount of cpus, negative on error, cpu_top must be
127 * passed to cpu_topology_release to free resources
129 * Array is sorted after ->pkg, ->core, then ->cpu
131 int get_cpu_topology(struct cpupower_topology *cpu_top)
133 int cpu, last_pkg, cpus = sysconf(_SC_NPROCESSORS_CONF);
135 cpu_top->core_info = malloc(sizeof(struct cpuid_core_info) * cpus);
136 if (cpu_top->core_info == NULL)
138 cpu_top->pkgs = cpu_top->cores = 0;
139 for (cpu = 0; cpu < cpus; cpu++) {
140 cpu_top->core_info[cpu].cpu = cpu;
141 cpu_top->core_info[cpu].is_online = cpupower_is_cpu_online(cpu);
142 if(sysfs_topology_read_file(
144 "physical_package_id",
145 &(cpu_top->core_info[cpu].pkg)) < 0) {
146 cpu_top->core_info[cpu].pkg = -1;
147 cpu_top->core_info[cpu].core = -1;
150 if(sysfs_topology_read_file(
153 &(cpu_top->core_info[cpu].core)) < 0) {
154 cpu_top->core_info[cpu].pkg = -1;
155 cpu_top->core_info[cpu].core = -1;
160 qsort(cpu_top->core_info, cpus, sizeof(struct cpuid_core_info),
163 /* Count the number of distinct pkgs values. This works
164 because the primary sort of the core_info struct was just
165 done by pkg value. */
166 last_pkg = cpu_top->core_info[0].pkg;
167 for(cpu = 1; cpu < cpus; cpu++) {
168 if (cpu_top->core_info[cpu].pkg != last_pkg &&
169 cpu_top->core_info[cpu].pkg != -1) {
171 last_pkg = cpu_top->core_info[cpu].pkg;
175 if (!(cpu_top->core_info[0].pkg == -1))
178 /* Intel's cores count is not consecutively numbered, there may
179 * be a core_id of 3, but none of 2. Assume there always is 0
180 * Get amount of cores by counting duplicates in a package
181 for (cpu = 0; cpu_top->core_info[cpu].pkg = 0 && cpu < cpus; cpu++) {
182 if (cpu_top->core_info[cpu].core == 0)
188 void cpu_topology_release(struct cpupower_topology cpu_top)
190 free(cpu_top.core_info);