1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * taskset - retrieve or set a processes' CPU affinity
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4 | * Copyright (c) 2006 Bernhard Reutner-Fischer
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5 | *
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6 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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7 | */
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8 |
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9 | //usage:#define taskset_trivial_usage
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10 | //usage: "[-p] [MASK] [PID | PROG ARGS]"
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11 | //usage:#define taskset_full_usage "\n\n"
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12 | //usage: "Set or get CPU affinity\n"
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13 | //usage: "\n -p Operate on an existing PID"
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14 | //usage:
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15 | //usage:#define taskset_example_usage
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16 | //usage: "$ taskset 0x7 ./dgemm_test&\n"
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17 | //usage: "$ taskset -p 0x1 $!\n"
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18 | //usage: "pid 4790's current affinity mask: 7\n"
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19 | //usage: "pid 4790's new affinity mask: 1\n"
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20 | //usage: "$ taskset 0x7 /bin/sh -c './taskset -p 0x1 $$'\n"
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21 | //usage: "pid 6671's current affinity mask: 1\n"
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22 | //usage: "pid 6671's new affinity mask: 1\n"
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23 | //usage: "$ taskset -p 1\n"
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24 | //usage: "pid 1's current affinity mask: 3\n"
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25 |
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26 | #include <sched.h>
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27 | #include "libbb.h"
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28 |
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29 | #if ENABLE_FEATURE_TASKSET_FANCY
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30 | #define TASKSET_PRINTF_MASK "%s"
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31 | /* craft a string from the mask */
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32 | static char *from_cpuset(cpu_set_t *mask)
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33 | {
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34 | int i;
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35 | char *ret = NULL;
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36 | char *str = xzalloc((CPU_SETSIZE / 4) + 1); /* we will leak it */
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37 |
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38 | for (i = CPU_SETSIZE - 4; i >= 0; i -= 4) {
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39 | int val = 0;
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40 | int off;
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41 | for (off = 0; off <= 3; ++off)
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42 | if (CPU_ISSET(i + off, mask))
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43 | val |= 1 << off;
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44 | if (!ret && val)
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45 | ret = str;
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46 | *str++ = bb_hexdigits_upcase[val] | 0x20;
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47 | }
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48 | return ret;
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49 | }
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50 | #else
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51 | #define TASKSET_PRINTF_MASK "%llx"
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52 | static unsigned long long from_cpuset(cpu_set_t *mask)
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53 | {
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54 | struct BUG_CPU_SETSIZE_is_too_small {
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55 | char BUG_CPU_SETSIZE_is_too_small[
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56 | CPU_SETSIZE < sizeof(int) ? -1 : 1];
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57 | };
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58 | char *p = (void*)mask;
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59 |
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60 | /* Take the least significant bits. Careful!
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61 | * Consider both CPU_SETSIZE=4 and CPU_SETSIZE=1024 cases
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62 | */
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63 | #if BB_BIG_ENDIAN
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64 | /* For big endian, it means LAST bits */
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65 | if (CPU_SETSIZE < sizeof(long))
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66 | p += CPU_SETSIZE - sizeof(int);
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67 | else if (CPU_SETSIZE < sizeof(long long))
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68 | p += CPU_SETSIZE - sizeof(long);
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69 | else
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70 | p += CPU_SETSIZE - sizeof(long long);
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71 | #endif
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72 | if (CPU_SETSIZE < sizeof(long))
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73 | return *(unsigned*)p;
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74 | if (CPU_SETSIZE < sizeof(long long))
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75 | return *(unsigned long*)p;
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76 | return *(unsigned long long*)p;
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77 | }
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78 | #endif
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79 |
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80 |
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81 | int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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82 | int taskset_main(int argc UNUSED_PARAM, char **argv)
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83 | {
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84 | cpu_set_t mask;
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85 | pid_t pid = 0;
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86 | unsigned opt_p;
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87 | const char *current_new;
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88 | char *pid_str;
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89 | char *aff = aff; /* for compiler */
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90 |
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91 | /* NB: we mimic util-linux's taskset: -p does not take
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92 | * an argument, i.e., "-pN" is NOT valid, only "-p N"!
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93 | * Indeed, util-linux-2.13-pre7 uses:
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94 | * getopt_long(argc, argv, "+pchV", ...), not "...p:..." */
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95 |
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96 | opt_complementary = "-1"; /* at least 1 arg */
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97 | opt_p = getopt32(argv, "+p");
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98 | argv += optind;
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99 |
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100 | if (opt_p) {
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101 | pid_str = *argv++;
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102 | if (*argv) { /* "-p <aff> <pid> ...rest.is.ignored..." */
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103 | aff = pid_str;
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104 | pid_str = *argv; /* NB: *argv != NULL in this case */
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105 | }
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106 | /* else it was just "-p <pid>", and *argv == NULL */
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107 | pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
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108 | } else {
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109 | aff = *argv++; /* <aff> <cmd...> */
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110 | if (!*argv)
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111 | bb_show_usage();
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112 | }
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113 |
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114 | current_new = "current\0new";
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115 | if (opt_p) {
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116 | print_aff:
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117 | if (sched_getaffinity(pid, sizeof(mask), &mask) < 0)
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118 | bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
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119 | printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
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120 | pid, current_new, from_cpuset(&mask));
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121 | if (!*argv) {
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122 | /* Either it was just "-p <pid>",
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123 | * or it was "-p <aff> <pid>" and we came here
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124 | * for the second time (see goto below) */
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125 | return EXIT_SUCCESS;
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126 | }
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127 | *argv = NULL;
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128 | current_new += 8; /* "new" */
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129 | }
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130 |
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131 | { /* Affinity was specified, translate it into cpu_set_t */
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132 | unsigned i;
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133 | /* Do not allow zero mask: */
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134 | unsigned long long m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
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135 | enum { CNT_BIT = CPU_SETSIZE < sizeof(m)*8 ? CPU_SETSIZE : sizeof(m)*8 };
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136 |
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137 | CPU_ZERO(&mask);
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138 | for (i = 0; i < CNT_BIT; i++) {
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139 | unsigned long long bit = (1ULL << i);
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140 | if (bit & m)
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141 | CPU_SET(i, &mask);
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142 | }
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143 | }
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144 |
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145 | /* Set pid's or our own (pid==0) affinity */
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146 | if (sched_setaffinity(pid, sizeof(mask), &mask))
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147 | bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid);
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148 |
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149 | if (!argv[0]) /* "-p <aff> <pid> [...ignored...]" */
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150 | goto print_aff; /* print new affinity and exit */
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151 |
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152 | BB_EXECVP_or_die(argv);
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153 | }
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