1 /* vi: set sw=4 ts=4: */
3 * chrt - manipulate real-time attributes of a process
4 * Copyright (c) 2006-2007 Bernhard Reutner-Fischer
6 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
10 #ifndef _POSIX_PRIORITY_SCHEDULING
11 #warning your system may be foobared
16 char name[sizeof("SCHED_OTHER")];
18 {SCHED_OTHER, "SCHED_OTHER"},
19 {SCHED_FIFO, "SCHED_FIFO"},
20 {SCHED_RR, "SCHED_RR"}
27 static void show_min_max(int pol)
29 const char *fmt = "%s min/max priority\t: %u/%u\n";
32 max = sched_get_priority_max(pol);
33 min = sched_get_priority_min(pol);
35 fmt = "%s not supported\n";
36 printf(fmt, policies[pol].name, min, max);
45 int chrt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
46 int chrt_main(int argc UNUSED_PARAM, char **argv)
50 struct sched_param sp;
52 char *priority = priority; /* for compiler */
53 const char *current_new;
54 int policy = SCHED_RR;
56 /* at least 1 arg; only one policy accepted */
57 opt_complementary = "-1:r--fo:f--ro:r--fo";
58 opt = getopt32(argv, "+mprfo");
65 if (opt & OPT_m) { /* print min/max */
66 show_min_max(SCHED_FIFO);
67 show_min_max(SCHED_RR);
68 show_min_max(SCHED_OTHER);
69 fflush_stdout_and_exit(EXIT_SUCCESS);
75 if (*argv) { /* "-p <priority> <pid> [...]" */
79 /* else "-p <pid>", and *argv == NULL */
80 pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
87 current_new = "current\0new";
91 pol = sched_getscheduler(pid);
93 bb_perror_msg_and_die("can't %cet pid %d's policy", 'g', pid);
94 printf("pid %d's %s scheduling policy: %s\n",
95 pid, current_new, policies[pol].name);
96 if (sched_getparam(pid, &sp))
97 bb_perror_msg_and_die("can't get pid %d's attributes", pid);
98 printf("pid %d's %s scheduling priority: %d\n",
99 pid, current_new, sp.sched_priority);
101 /* Either it was just "-p <pid>",
102 * or it was "-p <priority> <pid>" and we came here
103 * for the second time (see goto below) */
110 /* from the manpage of sched_getscheduler:
111 [...] sched_priority can have a value in the range 0 to 99.
112 [...] SCHED_OTHER or SCHED_BATCH must be assigned static priority 0.
113 [...] SCHED_FIFO or SCHED_RR can have static priority in 1..99 range.
115 sp.sched_priority = xstrtou_range(priority, 0, policy != SCHED_OTHER ? 1 : 0, 99);
117 if (sched_setscheduler(pid, policy, &sp) < 0)
118 bb_perror_msg_and_die("can't %cet pid %d's policy", 's', pid);
120 if (!argv[0]) /* "-p <priority> <pid> [...]" */
123 BB_EXECVP_or_die(argv);