1 /*
2 * taskset.c - set or retrieve a task's CPU affinity
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License, version 2, as
6 * published by the Free Software Foundation
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
16 *
17 * Copyright (C) 2004 Robert Love
18 * Copyright (C) 2010 Karel Zak <kzak@redhat.com>
19 */
20
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <unistd.h>
24 #include <getopt.h>
25 #include <errno.h>
26 #include <sched.h>
27 #include <stddef.h>
28 #include <string.h>
29
30 #include "cpuset.h"
31 #include "nls.h"
32 #include "strutils.h"
33 #include "xalloc.h"
34 #include "procfs.h"
35 #include "c.h"
36 #include "closestream.h"
37
38 #ifndef PF_NO_SETAFFINITY
39 # define PF_NO_SETAFFINITY 0x04000000
40 #endif
41
42 struct taskset {
43 pid_t pid; /* task PID */
44 cpu_set_t *set; /* task CPU mask */
45 size_t setsize;
46 char *buf; /* buffer for conversion from mask to string */
47 size_t buflen;
48 unsigned int use_list:1, /* use list rather than masks */
49 get_only:1; /* print the mask, but not modify */
50 };
51
52 static void __attribute__((__noreturn__)) usage(void)
53 {
54 FILE *out = stdout;
55 fprintf(out,
56 _("Usage: %s [options] [mask | cpu-list] [pid|cmd [args...]]\n\n"),
57 program_invocation_short_name);
58
59 fputs(USAGE_SEPARATOR, out);
60 fputs(_("Show or change the CPU affinity of a process.\n"), out);
61 fputs(USAGE_SEPARATOR, out);
62
63 fprintf(out, _(
64 "Options:\n"
65 " -a, --all-tasks operate on all the tasks (threads) for a given pid\n"
66 " -p, --pid operate on existing given pid\n"
67 " -c, --cpu-list display and specify cpus in list format\n"
68 ));
69 printf(USAGE_HELP_OPTIONS(25));
70
71 fputs(USAGE_SEPARATOR, out);
72 fprintf(out, _(
73 "The default behavior is to run a new command:\n"
74 " %1$s 03 sshd -b 1024\n"
75 "You can retrieve the mask of an existing task:\n"
76 " %1$s -p 700\n"
77 "Or set it:\n"
78 " %1$s -p 03 700\n"
79 "List format uses a comma-separated list instead of a mask:\n"
80 " %1$s -pc 0,3,7-11 700\n"
81 "Ranges in list format can take a stride argument:\n"
82 " e.g. 0-31:2 is equivalent to mask 0x55555555\n"),
83 program_invocation_short_name);
84
85 printf(USAGE_MAN_TAIL("taskset(1)"));
86 exit(EXIT_SUCCESS);
87 }
88
89 static void print_affinity(struct taskset *ts, int isnew)
90 {
91 char *str, *msg;
92
93 if (ts->use_list) {
94 str = cpulist_create(ts->buf, ts->buflen, ts->set, ts->setsize);
95 msg = isnew ? _("pid %d's new affinity list: %s\n") :
96 _("pid %d's current affinity list: %s\n");
97 } else {
98 str = cpumask_create(ts->buf, ts->buflen, ts->set, ts->setsize);
99 msg = isnew ? _("pid %d's new affinity mask: %s\n") :
100 _("pid %d's current affinity mask: %s\n");
101 }
102
103 if (!str)
104 errx(EXIT_FAILURE, _("internal error: conversion from cpuset to string failed"));
105
106 printf(msg, ts->pid ? ts->pid : getpid(), str);
107 }
108
109 static void __attribute__((__noreturn__)) err_affinity(pid_t pid, int set)
110 {
111 char *msg;
112
113 msg = set ? _("failed to set pid %d's affinity") :
114 _("failed to get pid %d's affinity");
115
116 err(EXIT_FAILURE, msg, pid ? pid : getpid());
117 }
118
119
120 static void do_taskset(struct taskset *ts, size_t setsize, cpu_set_t *set)
121 {
122 /* read the current mask */
123 if (ts->pid) {
124 if (sched_getaffinity(ts->pid, ts->setsize, ts->set) < 0)
125 err_affinity(ts->pid, 0);
126 print_affinity(ts, FALSE);
127 }
128
129 if (ts->get_only)
130 return;
131
132 /* set new mask */
133 if (sched_setaffinity(ts->pid, setsize, set) < 0) {
134 uintmax_t flags = 0;
135 struct path_cxt *pc;
136 int errsv = errno;
137
138 if (errno != EPERM
139 && (pc = ul_new_procfs_path(ts->pid, NULL))
140 && procfs_process_get_stat_nth(pc, 9, &flags) == 0
141 && (flags & PF_NO_SETAFFINITY)) {
142 warnx(_("affinity cannot be set due to PF_NO_SETAFFINITY flag set"));
143 errno = EINVAL;
144 } else
145 errno = errsv;
146
147 err_affinity(ts->pid, 1);
148 }
149
150 /* re-read the current mask */
151 if (ts->pid) {
152 if (sched_getaffinity(ts->pid, ts->setsize, ts->set) < 0)
153 err_affinity(ts->pid, 0);
154 print_affinity(ts, TRUE);
155 }
156 }
157
158 int main(int argc, char **argv)
159 {
160 cpu_set_t *new_set;
161 pid_t pid = 0;
162 int c, all_tasks = 0;
163 int ncpus;
164 size_t new_setsize, nbits;
165 struct taskset ts;
166
167 static const struct option longopts[] = {
168 { "all-tasks", 0, NULL, 'a' },
169 { "pid", 0, NULL, 'p' },
170 { "cpu-list", 0, NULL, 'c' },
171 { "help", 0, NULL, 'h' },
172 { "version", 0, NULL, 'V' },
173 { NULL, 0, NULL, 0 }
174 };
175
176 setlocale(LC_ALL, "");
177 bindtextdomain(PACKAGE, LOCALEDIR);
178 textdomain(PACKAGE);
179 close_stdout_atexit();
180
181 memset(&ts, 0, sizeof(ts));
182
183 while ((c = getopt_long(argc, argv, "+apchV", longopts, NULL)) != -1) {
184 switch (c) {
185 case 'a':
186 all_tasks = 1;
187 break;
188 case 'p':
189 pid = strtos32_or_err(argv[argc - 1],
190 _("invalid PID argument"));
191 break;
192 case 'c':
193 ts.use_list = 1;
194 break;
195
196 case 'V':
197 print_version(EXIT_SUCCESS);
198 case 'h':
199 usage();
200 default:
201 errtryhelp(EXIT_FAILURE);
202 }
203 }
204
205 if ((!pid && argc - optind < 2)
206 || (pid && (argc - optind < 1 || argc - optind > 2))) {
207 warnx(_("bad usage"));
208 errtryhelp(EXIT_FAILURE);
209 }
210
211 ncpus = get_max_number_of_cpus();
212 if (ncpus <= 0)
213 errx(EXIT_FAILURE, _("cannot determine NR_CPUS; aborting"));
214
215 /*
216 * the ts->set is always used for the sched_getaffinity call
217 * On the sched_getaffinity the kernel demands a user mask of
218 * at least the size of its own cpumask_t.
219 */
220 ts.set = cpuset_alloc(ncpus, &ts.setsize, &nbits);
221 if (!ts.set)
222 err(EXIT_FAILURE, _("cpuset_alloc failed"));
223
224 /* buffer for conversion from mask to string */
225 ts.buflen = 7 * nbits;
226 ts.buf = xmalloc(ts.buflen);
227
228 /*
229 * new_set is always used for the sched_setaffinity call
230 * On the sched_setaffinity the kernel will zero-fill its
231 * cpumask_t if the user's mask is shorter.
232 */
233 new_set = cpuset_alloc(ncpus, &new_setsize, NULL);
234 if (!new_set)
235 err(EXIT_FAILURE, _("cpuset_alloc failed"));
236
237 if (argc - optind == 1)
238 ts.get_only = 1;
239
240 else if (ts.use_list) {
241 if (cpulist_parse(argv[optind], new_set, new_setsize, 0))
242 errx(EXIT_FAILURE, _("failed to parse CPU list: %s"),
243 argv[optind]);
244 } else if (cpumask_parse(argv[optind], new_set, new_setsize)) {
245 errx(EXIT_FAILURE, _("failed to parse CPU mask: %s"),
246 argv[optind]);
247 }
248
249 if (all_tasks && pid) {
250 DIR *sub = NULL;
251 struct path_cxt *pc = ul_new_procfs_path(pid, NULL);
252
253 while (pc && procfs_process_next_tid(pc, &sub, &ts.pid) == 0)
254 do_taskset(&ts, new_setsize, new_set);
255
256 ul_unref_path(pc);
257 } else {
258 ts.pid = pid;
259 do_taskset(&ts, new_setsize, new_set);
260 }
261
262 free(ts.buf);
263 cpuset_free(ts.set);
264 cpuset_free(new_set);
265
266 if (!pid) {
267 argv += optind + 1;
268 execvp(argv[0], argv);
269 errexec(argv[0]);
270 }
271
272 return EXIT_SUCCESS;
273 }