blob: f2f559fd72d9909ecf3c149fcf0ceb4088bbd7b2
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 | |
9 | //usage:#define chrt_trivial_usage |
10 | //usage: "[-prfom] [PRIO] [PID | PROG ARGS]" |
11 | //usage:#define chrt_full_usage "\n\n" |
12 | //usage: "Change scheduling priority and class for a process\n" |
13 | //usage: "\n -p Operate on PID" |
14 | //usage: "\n -r Set SCHED_RR class" |
15 | //usage: "\n -f Set SCHED_FIFO class" |
16 | //usage: "\n -o Set SCHED_OTHER class" |
17 | //usage: "\n -m Show min/max priorities" |
18 | //usage: |
19 | //usage:#define chrt_example_usage |
20 | //usage: "$ chrt -r 4 sleep 900; x=$!\n" |
21 | //usage: "$ chrt -f -p 3 $x\n" |
22 | //usage: "You need CAP_SYS_NICE privileges to set scheduling attributes of a process" |
23 | |
24 | #include <sched.h> |
25 | #include "libbb.h" |
26 | |
27 | static const struct { |
28 | int policy; |
29 | char name[sizeof("SCHED_OTHER")]; |
30 | } policies[] = { |
31 | {SCHED_OTHER, "SCHED_OTHER"}, |
32 | {SCHED_FIFO, "SCHED_FIFO"}, |
33 | {SCHED_RR, "SCHED_RR"} |
34 | }; |
35 | |
36 | //TODO: add |
37 | // -b, SCHED_BATCH |
38 | // -i, SCHED_IDLE |
39 | |
40 | static void show_min_max(int pol) |
41 | { |
42 | const char *fmt = "%s min/max priority\t: %u/%u\n"; |
43 | int max, min; |
44 | |
45 | max = sched_get_priority_max(pol); |
46 | min = sched_get_priority_min(pol); |
47 | if ((max|min) < 0) |
48 | fmt = "%s not supported\n"; |
49 | printf(fmt, policies[pol].name, min, max); |
50 | } |
51 | |
52 | #define OPT_m (1<<0) |
53 | #define OPT_p (1<<1) |
54 | #define OPT_r (1<<2) |
55 | #define OPT_f (1<<3) |
56 | #define OPT_o (1<<4) |
57 | |
58 | int chrt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
59 | int chrt_main(int argc UNUSED_PARAM, char **argv) |
60 | { |
61 | pid_t pid = 0; |
62 | unsigned opt; |
63 | struct sched_param sp; |
64 | char *pid_str; |
65 | char *priority = priority; /* for compiler */ |
66 | const char *current_new; |
67 | int policy = SCHED_RR; |
68 | |
69 | /* only one policy accepted */ |
70 | opt_complementary = "r--fo:f--ro:o--rf"; |
71 | opt = getopt32(argv, "+mprfo"); |
72 | if (opt & OPT_m) { /* print min/max and exit */ |
73 | show_min_max(SCHED_FIFO); |
74 | show_min_max(SCHED_RR); |
75 | show_min_max(SCHED_OTHER); |
76 | fflush_stdout_and_exit(EXIT_SUCCESS); |
77 | } |
78 | if (opt & OPT_r) |
79 | policy = SCHED_RR; |
80 | if (opt & OPT_f) |
81 | policy = SCHED_FIFO; |
82 | if (opt & OPT_o) |
83 | policy = SCHED_OTHER; |
84 | |
85 | argv += optind; |
86 | if (!argv[0]) |
87 | bb_show_usage(); |
88 | if (opt & OPT_p) { |
89 | pid_str = *argv++; |
90 | if (*argv) { /* "-p <priority> <pid> [...]" */ |
91 | priority = pid_str; |
92 | pid_str = *argv; |
93 | } |
94 | /* else "-p <pid>", and *argv == NULL */ |
95 | pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1); |
96 | } else { |
97 | priority = *argv++; |
98 | if (!*argv) |
99 | bb_show_usage(); |
100 | } |
101 | |
102 | current_new = "current\0new"; |
103 | if (opt & OPT_p) { |
104 | int pol; |
105 | print_rt_info: |
106 | pol = sched_getscheduler(pid); |
107 | if (pol < 0) |
108 | bb_perror_msg_and_die("can't %cet pid %d's policy", 'g', (int)pid); |
109 | printf("pid %d's %s scheduling policy: %s\n", |
110 | pid, current_new, policies[pol].name); |
111 | if (sched_getparam(pid, &sp)) |
112 | bb_perror_msg_and_die("can't get pid %d's attributes", (int)pid); |
113 | printf("pid %d's %s scheduling priority: %d\n", |
114 | (int)pid, current_new, sp.sched_priority); |
115 | if (!*argv) { |
116 | /* Either it was just "-p <pid>", |
117 | * or it was "-p <priority> <pid>" and we came here |
118 | * for the second time (see goto below) */ |
119 | return EXIT_SUCCESS; |
120 | } |
121 | *argv = NULL; |
122 | current_new += 8; |
123 | } |
124 | |
125 | /* from the manpage of sched_getscheduler: |
126 | [...] sched_priority can have a value in the range 0 to 99. |
127 | [...] SCHED_OTHER or SCHED_BATCH must be assigned static priority 0. |
128 | [...] SCHED_FIFO or SCHED_RR can have static priority in 1..99 range. |
129 | */ |
130 | sp.sched_priority = xstrtou_range(priority, 0, policy != SCHED_OTHER ? 1 : 0, 99); |
131 | |
132 | if (sched_setscheduler(pid, policy, &sp) < 0) |
133 | bb_perror_msg_and_die("can't %cet pid %d's policy", 's', (int)pid); |
134 | |
135 | if (!argv[0]) /* "-p <priority> <pid> [...]" */ |
136 | goto print_rt_info; |
137 | |
138 | BB_EXECVP_or_die(argv); |
139 | } |
140 |