/* 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-$(CONFIG_CHRT) += chrt.o //usage:#define chrt_trivial_usage //usage: "[-prfom] [PRIO] [PID | PROG ARGS]" //usage:#define chrt_full_usage "\n\n" //usage: "Change scheduling priority and class for a process\n" //usage: "\n -p Operate on PID" //usage: "\n -r Set SCHED_RR class" //usage: "\n -f Set SCHED_FIFO class" //usage: "\n -o Set SCHED_OTHER class" //usage: "\n -m Show min/max priorities" //usage: //usage:#define chrt_example_usage //usage: "$ 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"} }; //TODO: add // -b, SCHED_BATCH // -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) 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, "^+" "mprfo" "\0" "r--fo:f--ro:o--rf"); if (opt & OPT_m) { /* print min/max and exit */ show_min_max(SCHED_FIFO); show_min_max(SCHED_RR); show_min_max(SCHED_OTHER); 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; 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 ? 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); }