| 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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