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