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