1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * chrt - manipulate real-time attributes of a process
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4 | * Copyright (c) 2006-2007 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 chrt_trivial_usage
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10 | //usage: "[-prfom] [PRIO] [PID | PROG ARGS]"
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11 | //usage:#define chrt_full_usage "\n\n"
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12 | //usage: "Change scheduling priority and class for a process\n"
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13 | //usage: "\n -p Operate on PID"
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14 | //usage: "\n -r Set SCHED_RR class"
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15 | //usage: "\n -f Set SCHED_FIFO class"
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16 | //usage: "\n -o Set SCHED_OTHER class"
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17 | //usage: "\n -m Show min/max priorities"
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18 | //usage:
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19 | //usage:#define chrt_example_usage
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20 | //usage: "$ chrt -r 4 sleep 900; x=$!\n"
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21 | //usage: "$ chrt -f -p 3 $x\n"
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22 | //usage: "You need CAP_SYS_NICE privileges to set scheduling attributes of a process"
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23 |
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24 | #include <sched.h>
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25 | #include "libbb.h"
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26 |
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27 | static const struct {
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28 | int policy;
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29 | char name[sizeof("SCHED_OTHER")];
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30 | } policies[] = {
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31 | {SCHED_OTHER, "SCHED_OTHER"},
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32 | {SCHED_FIFO, "SCHED_FIFO"},
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33 | {SCHED_RR, "SCHED_RR"}
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34 | };
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35 |
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36 | //TODO: add
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37 | // -b, SCHED_BATCH
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38 | // -i, SCHED_IDLE
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39 |
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40 | static void show_min_max(int pol)
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41 | {
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42 | const char *fmt = "%s min/max priority\t: %u/%u\n";
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43 | int max, min;
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44 |
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45 | max = sched_get_priority_max(pol);
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46 | min = sched_get_priority_min(pol);
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47 | if ((max|min) < 0)
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48 | fmt = "%s not supported\n";
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49 | printf(fmt, policies[pol].name, min, max);
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50 | }
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51 |
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52 | #define OPT_m (1<<0)
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53 | #define OPT_p (1<<1)
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54 | #define OPT_r (1<<2)
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55 | #define OPT_f (1<<3)
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56 | #define OPT_o (1<<4)
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57 |
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58 | int chrt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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59 | int chrt_main(int argc UNUSED_PARAM, char **argv)
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60 | {
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61 | pid_t pid = 0;
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62 | unsigned opt;
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63 | struct sched_param sp;
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64 | char *pid_str;
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65 | char *priority = priority; /* for compiler */
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66 | const char *current_new;
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67 | int policy = SCHED_RR;
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68 |
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69 | /* only one policy accepted */
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70 | opt_complementary = "r--fo:f--ro:o--rf";
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71 | opt = getopt32(argv, "+mprfo");
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72 | if (opt & OPT_m) { /* print min/max and exit */
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73 | show_min_max(SCHED_FIFO);
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74 | show_min_max(SCHED_RR);
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75 | show_min_max(SCHED_OTHER);
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76 | fflush_stdout_and_exit(EXIT_SUCCESS);
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77 | }
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78 | if (opt & OPT_r)
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79 | policy = SCHED_RR;
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80 | if (opt & OPT_f)
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81 | policy = SCHED_FIFO;
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82 | if (opt & OPT_o)
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83 | policy = SCHED_OTHER;
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84 |
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85 | argv += optind;
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86 | if (!argv[0])
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87 | bb_show_usage();
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88 | if (opt & OPT_p) {
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89 | pid_str = *argv++;
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90 | if (*argv) { /* "-p <priority> <pid> [...]" */
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91 | priority = pid_str;
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92 | pid_str = *argv;
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93 | }
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94 | /* else "-p <pid>", and *argv == NULL */
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95 | pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
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96 | } else {
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97 | priority = *argv++;
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98 | if (!*argv)
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99 | bb_show_usage();
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100 | }
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101 |
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102 | current_new = "current\0new";
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103 | if (opt & OPT_p) {
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104 | int pol;
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105 | print_rt_info:
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106 | pol = sched_getscheduler(pid);
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107 | if (pol < 0)
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108 | bb_perror_msg_and_die("can't %cet pid %d's policy", 'g', (int)pid);
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109 | printf("pid %d's %s scheduling policy: %s\n",
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110 | pid, current_new, policies[pol].name);
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111 | if (sched_getparam(pid, &sp))
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112 | bb_perror_msg_and_die("can't get pid %d's attributes", (int)pid);
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113 | printf("pid %d's %s scheduling priority: %d\n",
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114 | (int)pid, current_new, sp.sched_priority);
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115 | if (!*argv) {
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116 | /* Either it was just "-p <pid>",
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117 | * or it was "-p <priority> <pid>" and we came here
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118 | * for the second time (see goto below) */
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119 | return EXIT_SUCCESS;
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120 | }
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121 | *argv = NULL;
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122 | current_new += 8;
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123 | }
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124 |
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125 | /* from the manpage of sched_getscheduler:
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126 | [...] sched_priority can have a value in the range 0 to 99.
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127 | [...] SCHED_OTHER or SCHED_BATCH must be assigned static priority 0.
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128 | [...] SCHED_FIFO or SCHED_RR can have static priority in 1..99 range.
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129 | */
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130 | sp.sched_priority = xstrtou_range(priority, 0, policy != SCHED_OTHER ? 1 : 0, 99);
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131 |
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132 | if (sched_setscheduler(pid, policy, &sp) < 0)
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133 | bb_perror_msg_and_die("can't %cet pid %d's policy", 's', (int)pid);
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134 |
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135 | if (!argv[0]) /* "-p <priority> <pid> [...]" */
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136 | goto print_rt_info;
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137 |
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138 | BB_EXECVP_or_die(argv);
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139 | }
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