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 Fischer
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5 | *
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6 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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7 | */
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8 |
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9 | #include <sched.h>
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10 | #include <getopt.h> /* optind */
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11 | #include "libbb.h"
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12 | #ifndef _POSIX_PRIORITY_SCHEDULING
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13 | #warning your system may be foobared
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14 | #endif
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15 | static const struct {
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16 | const int policy;
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17 | const char const name[12];
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18 | } policies[] = {
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19 | {SCHED_OTHER, "SCHED_OTHER"},
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20 | {SCHED_FIFO, "SCHED_FIFO"},
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21 | {SCHED_RR, "SCHED_RR"}
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22 | };
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23 |
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24 | static void show_min_max(int pol)
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25 | {
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26 | const char *fmt = "%s min/max priority\t: %d/%d\n\0%s not supported?\n";
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27 | int max, min;
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28 | max = sched_get_priority_max(pol);
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29 | min = sched_get_priority_min(pol);
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30 | if (max >= 0 && min >= 0)
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31 | printf(fmt, policies[pol].name, min, max);
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32 | else {
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33 | fmt += 29;
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34 | printf(fmt, policies[pol].name);
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35 | }
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36 | }
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37 |
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38 | #define OPT_m (1<<0)
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39 | #define OPT_p (1<<1)
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40 | #define OPT_r (1<<2)
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41 | #define OPT_f (1<<3)
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42 | #define OPT_o (1<<4)
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43 |
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44 | int chrt_main(int argc, char** argv);
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45 | int chrt_main(int argc, char** argv)
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46 | {
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47 | pid_t pid = 0;
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48 | unsigned opt;
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49 | struct sched_param sp;
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50 | char *p_opt = NULL, *priority = NULL;
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51 | const char *state = "current\0new";
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52 | int prio = 0, policy = SCHED_RR;
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53 |
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54 | opt_complementary = "r--fo:f--ro:r--fo"; /* only one policy accepted */
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55 | opt = getopt32(argv, "+mp:rfo", &p_opt);
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56 | if (opt & OPT_r)
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57 | policy = SCHED_RR;
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58 | if (opt & OPT_f)
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59 | policy = SCHED_FIFO;
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60 | if (opt & OPT_o)
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61 | policy = SCHED_OTHER;
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62 |
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63 | if (opt & OPT_m) { /* print min/max */
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64 | show_min_max(SCHED_FIFO);
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65 | show_min_max(SCHED_RR);
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66 | show_min_max(SCHED_OTHER);
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67 | fflush_stdout_and_exit(EXIT_SUCCESS);
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68 | }
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69 | if (opt & OPT_p) {
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70 | if (argc == optind+1) { /* -p <priority> <pid> */
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71 | priority = p_opt;
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72 | p_opt = argv[optind];
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73 | }
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74 | argv += optind; /* me -p <arg> */
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75 | pid = xatoul_range(p_opt, 1, ULONG_MAX); /* -p <pid> */
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76 | } else {
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77 | argv += optind; /* me -p <arg> */
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78 | priority = *argv;
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79 | }
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80 | if (priority) {
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81 | /* from the manpage of sched_getscheduler:
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82 | [...] sched_priority can have a value
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83 | in the range 0 to 99.
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84 | [...] SCHED_OTHER or SCHED_BATCH must be assigned
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85 | the static priority 0. [...] SCHED_FIFO or
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86 | SCHED_RR can have a static priority in the range 1 to 99.
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87 | */
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88 | prio = xstrtol_range(priority, 0, policy == SCHED_OTHER
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89 | ? 0 : 1, 99);
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90 | }
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91 |
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92 | if (opt & OPT_p) {
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93 | int pol = 0;
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94 | print_rt_info:
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95 | pol = sched_getscheduler(pid);
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96 | if (pol < 0)
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97 | bb_perror_msg_and_die("failed to %cet pid %d's policy", 'g', pid);
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98 | printf("pid %d's %s scheduling policy: %s\n",
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99 | pid, state, policies[pol].name);
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100 | if (sched_getparam(pid, &sp))
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101 | bb_perror_msg_and_die("failed to get pid %d's attributes", pid);
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102 | printf("pid %d's %s scheduling priority: %d\n",
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103 | pid, state, sp.sched_priority);
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104 | if (!*argv) /* no new prio given or we did print already, done. */
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105 | return EXIT_SUCCESS;
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106 | }
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107 |
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108 | sp.sched_priority = prio;
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109 | if (sched_setscheduler(pid, policy, &sp) < 0)
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110 | bb_perror_msg_and_die("failed to %cet pid %d's policy", 's', pid);
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111 | if (opt & OPT_p) {
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112 | state += 8;
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113 | ++argv;
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114 | goto print_rt_info;
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115 | }
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116 | ++argv;
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117 | BB_EXECVP(*argv, argv);
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118 | bb_perror_msg_and_die("%s", *argv);
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119 | }
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120 | #undef OPT_p
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121 | #undef OPT_r
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122 | #undef OPT_f
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123 | #undef OPT_o
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124 | #undef OPT_m
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