1 /*
2 *
3 * Copyright (c) Novell Inc. 2011
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms in version 2 of the GNU General Public License as
7 * published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
12 * the GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 *
18 * Author: Peter W. Morreale <pmorreale AT novell DOT com>
19 * Date: 11/08/2011
20 */
21
22 /*
23 * Must be ported to OS's other than Linux
24 */
25
26 #ifdef __linux__
27 # define _GNU_SOURCE
28 # define AFFINITY_NEEDS_GNU_SOURCE 1
29 # include <sched.h>
30 # include <stdio.h>
31
set_affinity(int cpu)32 static int set_affinity(int cpu)
33 {
34 cpu_set_t mask;
35
36 CPU_ZERO(&mask);
37 CPU_SET(cpu, &mask);
38
39 return (sched_setaffinity(0, sizeof(cpu_set_t), &mask));
40 }
41
get_online_cpu_from_sysfs(void)42 static int get_online_cpu_from_sysfs(void)
43 {
44 FILE *f;
45 int cpu = -1;
46
47 f = fopen("/sys/devices/system/cpu/online", "r");
48 if (!f)
49 return -1;
50 fscanf(f, "%d", &cpu);
51 fclose(f);
52
53 return cpu;
54 }
55
get_online_cpu_from_cpuinfo(void)56 static int get_online_cpu_from_cpuinfo(void)
57 {
58 FILE *f;
59 int cpu = -1;
60 char line[4096];
61
62 f = fopen("/proc/cpuinfo", "r");
63 if (!f)
64 return -1;
65
66 while (!feof(f)) {
67 if (!fgets(line, sizeof(line), f))
68 return -1;
69 /*
70 * cpuinfo output is not consistent across all archictures,
71 * it can be "processor : N", but for example on s390
72 * it's: "processor N: ...", so ignore any non-number
73 * after "processor"
74 */
75 if (sscanf(line, "processor%*[^0123456789]%d", &cpu) == 1)
76 break;
77 }
78 fclose(f);
79
80 return cpu;
81 }
82
set_affinity_single(void)83 static int set_affinity_single(void)
84 {
85 int cpu;
86
87 cpu = get_online_cpu_from_sysfs();
88 if (cpu >= 0)
89 goto set_affinity;
90
91 cpu = get_online_cpu_from_cpuinfo();
92 if (cpu >= 0)
93 goto set_affinity;
94
95 fprintf(stderr, "WARNING: Failed to detect online cpu, using cpu=0\n");
96 cpu = 0;
97 set_affinity:
98 return set_affinity(cpu);
99 }
100
101 #else
set_affinity_single(void)102 static int set_affinity_single(void)
103 {
104 errno = ENOSYS;
105 return -1;
106 }
107 #endif
108