summaryrefslogtreecommitdiff
path: root/tools/power/cpupower/lib/cpupower.c
blob: 9c395ec924def2538e973eab7724472eea34cb8d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
/*
 *  (C) 2004-2009  Dominik Brodowski <linux@dominikbrodowski.de>
 *
 *  Licensed under the terms of the GNU GPL License version 2.
 */

#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 sysfs_read_file(const char *path, char *buf, size_t buflen)
{
	int fd;
	ssize_t numread;

	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;
}

/*
 * 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 (sysfs_read_file(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);
}