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/* vi: set sw=4 ts=4: */
/*
* chrt - manipulate real-time attributes of a process
* Copyright (c) 2006-2007 Bernhard Reutner-Fischer
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//config:config CHRT
//config: bool "chrt (4.4 kb)"
//config: default y
//config: help
//config: manipulate real-time attributes of a process.
//config: This requires sched_{g,s}etparam support in your libc.
//applet:IF_CHRT(APPLET_NOEXEC(chrt, chrt, BB_DIR_USR_BIN, BB_SUID_DROP, chrt))
//kbuild:lib-$(CONFIG_CHRT) += chrt.o
//usage:#define chrt_trivial_usage
//usage: "[-prfomb] [PRIO] [PID | PROG ARGS]"
//usage:#define chrt_full_usage "\n\n"
//usage: "Change scheduling priority and class for a process\n"
//usage: "\n -p Operate on PID"
//usage: "\n -r Set SCHED_RR class"
//usage: "\n -f Set SCHED_FIFO class"
//usage: "\n -o Set SCHED_OTHER class"
//usage: "\n -b Set SCHED_BATCH class"
//usage: "\n -m Show min/max priorities"
//usage:
//usage:#define chrt_example_usage
//usage: "$ chrt -r 4 sleep 900; x=$!\n"
//usage: "$ chrt -f -p 3 $x\n"
//usage: "You need CAP_SYS_NICE privileges to set scheduling attributes of a process"
#include <sched.h>
#include "libbb.h"
static const struct {
int policy;
char name[sizeof("SCHED_OTHER")];
} policies[] = {
{SCHED_OTHER, "SCHED_OTHER"},
{SCHED_FIFO, "SCHED_FIFO"},
{SCHED_RR, "SCHED_RR"},
{SCHED_BATCH, "SCHED_BATCH"}
};
//TODO: add
// -i, SCHED_IDLE
static void show_min_max(int pol)
{
const char *fmt = "%s min/max priority\t: %u/%u\n";
int max, min;
max = sched_get_priority_max(pol);
min = sched_get_priority_min(pol);
if ((max|min) < 0)
fmt = "%s not supported\n";
printf(fmt, policies[pol].name, min, max);
}
#define OPT_m (1<<0)
#define OPT_p (1<<1)
#define OPT_r (1<<2)
#define OPT_f (1<<3)
#define OPT_o (1<<4)
#define OPT_b (1<<5)
int chrt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int chrt_main(int argc UNUSED_PARAM, char **argv)
{
pid_t pid = 0;
unsigned opt;
struct sched_param sp;
char *pid_str;
char *priority = priority; /* for compiler */
const char *current_new;
int policy = SCHED_RR;
/* only one policy accepted */
opt = getopt32(argv, "^+" "mprfob" "\0" "r--fob:f--rob:o--rfb:b--rfo");
if (opt & OPT_m) { /* print min/max and exit */
show_min_max(SCHED_FIFO);
show_min_max(SCHED_RR);
show_min_max(SCHED_OTHER);
show_min_max(SCHED_BATCH);
fflush_stdout_and_exit(EXIT_SUCCESS);
}
if (opt & OPT_r)
policy = SCHED_RR;
if (opt & OPT_f)
policy = SCHED_FIFO;
if (opt & OPT_o)
policy = SCHED_OTHER;
if (opt & OPT_b)
policy = SCHED_BATCH;
argv += optind;
if (!argv[0])
bb_show_usage();
if (opt & OPT_p) {
pid_str = *argv++;
if (*argv) { /* "-p <priority> <pid> [...]" */
priority = pid_str;
pid_str = *argv;
}
/* else "-p <pid>", and *argv == NULL */
pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
} else {
priority = *argv++;
if (!*argv)
bb_show_usage();
}
current_new = "current\0new";
if (opt & OPT_p) {
int pol;
print_rt_info:
pol = sched_getscheduler(pid);
if (pol < 0)
bb_perror_msg_and_die("can't %cet pid %d's policy", 'g', (int)pid);
printf("pid %d's %s scheduling policy: %s\n",
pid, current_new, policies[pol].name);
if (sched_getparam(pid, &sp))
bb_perror_msg_and_die("can't get pid %d's attributes", (int)pid);
printf("pid %d's %s scheduling priority: %d\n",
(int)pid, current_new, sp.sched_priority);
if (!*argv) {
/* Either it was just "-p <pid>",
* or it was "-p <priority> <pid>" and we came here
* for the second time (see goto below) */
return EXIT_SUCCESS;
}
*argv = NULL;
current_new += 8;
}
/* from the manpage of sched_getscheduler:
[...] sched_priority can have a value in the range 0 to 99.
[...] SCHED_OTHER or SCHED_BATCH must be assigned static priority 0.
[...] SCHED_FIFO or SCHED_RR can have static priority in 1..99 range.
*/
sp.sched_priority = xstrtou_range(priority, 0,
(policy != SCHED_OTHER && policy != SCHED_BATCH) ? 1 : 0, 99);
if (sched_setscheduler(pid, policy, &sp) < 0)
bb_perror_msg_and_die("can't %cet pid %d's policy", 's', (int)pid);
if (!argv[0]) /* "-p <priority> <pid> [...]" */
goto print_rt_info;
BB_EXECVP_or_die(argv);
}
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