schedutils/taskset.c

   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         fprintf(out, 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         fprintf(out, 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 }