blob: 1604a689069ee16f91f40f021f0c85240baa91b7
| 1 | /* vi: set sw=4 ts=4: */ |
| 2 | /* |
| 3 | * chrt - manipulate real-time attributes of a process |
| 4 | * Copyright (c) 2006-2007 Bernhard Reutner-Fischer |
| 5 | * |
| 6 | * Licensed under GPLv2 or later, see file LICENSE in this source tree. |
| 7 | */ |
| 8 | //config:config CHRT |
| 9 | //config: bool "chrt" |
| 10 | //config: default y |
| 11 | //config: help |
| 12 | //config: manipulate real-time attributes of a process. |
| 13 | //config: This requires sched_{g,s}etparam support in your libc. |
| 14 | |
| 15 | //applet:IF_CHRT(APPLET(chrt, BB_DIR_USR_BIN, BB_SUID_DROP)) |
| 16 | |
| 17 | //kbuild:lib-$(CONFIG_CHRT) += chrt.o |
| 18 | |
| 19 | //usage:#define chrt_trivial_usage |
| 20 | //usage: "[-prfom] [PRIO] [PID | PROG ARGS]" |
| 21 | //usage:#define chrt_full_usage "\n\n" |
| 22 | //usage: "Change scheduling priority and class for a process\n" |
| 23 | //usage: "\n -p Operate on PID" |
| 24 | //usage: "\n -r Set SCHED_RR class" |
| 25 | //usage: "\n -f Set SCHED_FIFO class" |
| 26 | //usage: "\n -o Set SCHED_OTHER class" |
| 27 | //usage: "\n -m Show min/max priorities" |
| 28 | //usage: |
| 29 | //usage:#define chrt_example_usage |
| 30 | //usage: "$ chrt -r 4 sleep 900; x=$!\n" |
| 31 | //usage: "$ chrt -f -p 3 $x\n" |
| 32 | //usage: "You need CAP_SYS_NICE privileges to set scheduling attributes of a process" |
| 33 | |
| 34 | #include <sched.h> |
| 35 | #include "libbb.h" |
| 36 | |
| 37 | static const struct { |
| 38 | int policy; |
| 39 | char name[sizeof("SCHED_OTHER")]; |
| 40 | } policies[] = { |
| 41 | {SCHED_OTHER, "SCHED_OTHER"}, |
| 42 | {SCHED_FIFO, "SCHED_FIFO"}, |
| 43 | {SCHED_RR, "SCHED_RR"} |
| 44 | }; |
| 45 | |
| 46 | //TODO: add |
| 47 | // -b, SCHED_BATCH |
| 48 | // -i, SCHED_IDLE |
| 49 | |
| 50 | static void show_min_max(int pol) |
| 51 | { |
| 52 | const char *fmt = "%s min/max priority\t: %u/%u\n"; |
| 53 | int max, min; |
| 54 | |
| 55 | max = sched_get_priority_max(pol); |
| 56 | min = sched_get_priority_min(pol); |
| 57 | if ((max|min) < 0) |
| 58 | fmt = "%s not supported\n"; |
| 59 | printf(fmt, policies[pol].name, min, max); |
| 60 | } |
| 61 | |
| 62 | #define OPT_m (1<<0) |
| 63 | #define OPT_p (1<<1) |
| 64 | #define OPT_r (1<<2) |
| 65 | #define OPT_f (1<<3) |
| 66 | #define OPT_o (1<<4) |
| 67 | |
| 68 | int chrt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
| 69 | int chrt_main(int argc UNUSED_PARAM, char **argv) |
| 70 | { |
| 71 | pid_t pid = 0; |
| 72 | unsigned opt; |
| 73 | struct sched_param sp; |
| 74 | char *pid_str; |
| 75 | char *priority = priority; /* for compiler */ |
| 76 | const char *current_new; |
| 77 | int policy = SCHED_RR; |
| 78 | |
| 79 | /* only one policy accepted */ |
| 80 | opt_complementary = "r--fo:f--ro:o--rf"; |
| 81 | opt = getopt32(argv, "+mprfo"); |
| 82 | if (opt & OPT_m) { /* print min/max and exit */ |
| 83 | show_min_max(SCHED_FIFO); |
| 84 | show_min_max(SCHED_RR); |
| 85 | show_min_max(SCHED_OTHER); |
| 86 | fflush_stdout_and_exit(EXIT_SUCCESS); |
| 87 | } |
| 88 | if (opt & OPT_r) |
| 89 | policy = SCHED_RR; |
| 90 | if (opt & OPT_f) |
| 91 | policy = SCHED_FIFO; |
| 92 | if (opt & OPT_o) |
| 93 | policy = SCHED_OTHER; |
| 94 | |
| 95 | argv += optind; |
| 96 | if (!argv[0]) |
| 97 | bb_show_usage(); |
| 98 | if (opt & OPT_p) { |
| 99 | pid_str = *argv++; |
| 100 | if (*argv) { /* "-p <priority> <pid> [...]" */ |
| 101 | priority = pid_str; |
| 102 | pid_str = *argv; |
| 103 | } |
| 104 | /* else "-p <pid>", and *argv == NULL */ |
| 105 | pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1); |
| 106 | } else { |
| 107 | priority = *argv++; |
| 108 | if (!*argv) |
| 109 | bb_show_usage(); |
| 110 | } |
| 111 | |
| 112 | current_new = "current\0new"; |
| 113 | if (opt & OPT_p) { |
| 114 | int pol; |
| 115 | print_rt_info: |
| 116 | pol = sched_getscheduler(pid); |
| 117 | if (pol < 0) |
| 118 | bb_perror_msg_and_die("can't %cet pid %d's policy", 'g', (int)pid); |
| 119 | printf("pid %d's %s scheduling policy: %s\n", |
| 120 | pid, current_new, policies[pol].name); |
| 121 | if (sched_getparam(pid, &sp)) |
| 122 | bb_perror_msg_and_die("can't get pid %d's attributes", (int)pid); |
| 123 | printf("pid %d's %s scheduling priority: %d\n", |
| 124 | (int)pid, current_new, sp.sched_priority); |
| 125 | if (!*argv) { |
| 126 | /* Either it was just "-p <pid>", |
| 127 | * or it was "-p <priority> <pid>" and we came here |
| 128 | * for the second time (see goto below) */ |
| 129 | return EXIT_SUCCESS; |
| 130 | } |
| 131 | *argv = NULL; |
| 132 | current_new += 8; |
| 133 | } |
| 134 | |
| 135 | /* from the manpage of sched_getscheduler: |
| 136 | [...] sched_priority can have a value in the range 0 to 99. |
| 137 | [...] SCHED_OTHER or SCHED_BATCH must be assigned static priority 0. |
| 138 | [...] SCHED_FIFO or SCHED_RR can have static priority in 1..99 range. |
| 139 | */ |
| 140 | sp.sched_priority = xstrtou_range(priority, 0, policy != SCHED_OTHER ? 1 : 0, 99); |
| 141 | |
| 142 | if (sched_setscheduler(pid, policy, &sp) < 0) |
| 143 | bb_perror_msg_and_die("can't %cet pid %d's policy", 's', (int)pid); |
| 144 | |
| 145 | if (!argv[0]) /* "-p <priority> <pid> [...]" */ |
| 146 | goto print_rt_info; |
| 147 | |
| 148 | BB_EXECVP_or_die(argv); |
| 149 | } |
| 150 |