| /* 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 (4.7 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-$(CONFIG_CHRT) += chrt.o |
| |
| //usage:#define chrt_trivial_usage |
| //usage: "-m | -p [PRIO] PID | [-rfobi] PRIO PROG ARGS" |
| //usage:#define chrt_full_usage "\n\n" |
| //usage: "Change scheduling priority and class for a process\n" |
| //usage: "\n -m Show min/max priorities" |
| //usage: "\n -p Operate on PID" |
| //usage: "\n -r Set SCHED_RR class" |
| //usage: "\n -f Set SCHED_FIFO class" |
| //usage: "\n -o Set SCHED_OTHER class" |
| //usage: "\n -b Set SCHED_BATCH class" |
| //usage: "\n -i Set SCHED_IDLE class" |
| //usage: |
| //usage:#define chrt_example_usage |
| //usage: "$ 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" |
| #ifndef SCHED_IDLE |
| # define SCHED_IDLE 5 |
| #endif |
| |
| //musl has no __MUSL__ or similar define to check for, |
| //but its <sys/types.h> has these lines: |
| // #define __NEED_fsblkcnt_t |
| // #define __NEED_fsfilcnt_t |
| #if defined(__linux__) && defined(__NEED_fsblkcnt_t) && defined(__NEED_fsfilcnt_t) |
| # define LIBC_IS_MUSL 1 |
| # include <sys/syscall.h> |
| #else |
| # define LIBC_IS_MUSL 0 |
| #endif |
| |
| static const char *policy_name(int pol) |
| { |
| if (pol > 6) |
| return utoa(pol); |
| return nth_string( |
| "OTHER" "\0" /* 0:SCHED_OTHER */ |
| "FIFO" "\0" /* 1:SCHED_FIFO */ |
| "RR" "\0" /* 2:SCHED_RR */ |
| "BATCH" "\0" /* 3:SCHED_BATCH */ |
| "ISO" "\0" /* 4:SCHED_ISO */ |
| "IDLE" "\0" /* 5:SCHED_IDLE */ |
| "DEADLINE", /* 6:SCHED_DEADLINE */ |
| pol |
| ); |
| } |
| |
| static void show_min_max(int pol) |
| { |
| const char *fmt = "SCHED_%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 = "SCHED_%s not supported\n"; |
| printf(fmt, policy_name(pol), 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) |
| #define OPT_i (1<<6) |
| |
| 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; |
| int ret; |
| |
| opt = getopt32(argv, "^" |
| "+" "mprfobi" |
| "\0" |
| /* only one policy accepted: */ |
| "r--fobi:f--robi:o--rfbi:b--rfoi:i--rfob" |
| ); |
| if (opt & OPT_m) { /* print min/max and exit */ |
| show_min_max(SCHED_OTHER); |
| show_min_max(SCHED_FIFO); |
| show_min_max(SCHED_RR); |
| show_min_max(SCHED_BATCH); |
| show_min_max(SCHED_IDLE); |
| fflush_stdout_and_exit(EXIT_SUCCESS); |
| } |
| //if (opt & OPT_r) |
| // policy = SCHED_RR; - default, already set |
| if (opt & OPT_f) |
| policy = SCHED_FIFO; |
| if (opt & OPT_o) |
| policy = SCHED_OTHER; |
| if (opt & OPT_b) |
| policy = SCHED_BATCH; |
| if (opt & OPT_i) |
| policy = SCHED_IDLE; |
| |
| argv += optind; |
| if (!argv[0]) |
| bb_show_usage(); |
| if (opt & OPT_p) { |
| pid_str = *argv++; |
| if (*argv) { /* "-p PRIO 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: |
| #if LIBC_IS_MUSL |
| /* musl libc returns ENOSYS for its sched_getscheduler library |
| * function, because the sched_getscheduler Linux kernel system call |
| * does not conform to Posix; so we use the system call directly |
| */ |
| pol = syscall(SYS_sched_getscheduler, pid); |
| #else |
| pol = sched_getscheduler(pid); |
| #endif |
| if (pol < 0) |
| bb_perror_msg_and_die("can't %cet pid %u's policy", 'g', (int)pid); |
| #ifdef SCHED_RESET_ON_FORK |
| /* "Since Linux 2.6.32, the SCHED_RESET_ON_FORK flag |
| * can be ORed in policy when calling sched_setscheduler(). |
| * As a result of including this flag, children created by |
| * fork(2) do not inherit privileged scheduling policies" |
| * |
| * This bit is also returned by sched_getscheduler()! |
| * (TODO: do we want to show it?) |
| */ |
| pol &= ~SCHED_RESET_ON_FORK; |
| #endif |
| printf("pid %u's %s scheduling policy: SCHED_%s\n", |
| pid, current_new, policy_name(pol) |
| ); |
| #if LIBC_IS_MUSL |
| ret = syscall(SYS_sched_getparam, pid, &sp); |
| #else |
| ret = sched_getparam(pid, &sp); |
| #endif |
| if (ret) |
| bb_perror_msg_and_die("can't get pid %u's attributes", (int)pid); |
| printf("pid %u'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 PRIO PID" and we came here |
| * for the second time (see goto below) */ |
| return EXIT_SUCCESS; |
| } |
| *argv = NULL; |
| current_new += 8; |
| } |
| |
| sp.sched_priority = xstrtou_range(priority, 0, |
| sched_get_priority_min(policy), sched_get_priority_max(policy) |
| ); |
| |
| #if LIBC_IS_MUSL |
| ret = syscall(SYS_sched_setscheduler, pid, policy, &sp); |
| #else |
| ret = sched_setscheduler(pid, policy, &sp); |
| #endif |
| if (ret) |
| bb_perror_msg_and_die("can't %cet pid %u's policy", 's', (int)pid); |
| |
| if (!argv[0]) /* "-p PRIO PID [...]" */ |
| goto print_rt_info; |
| |
| BB_EXECVP_or_die(argv); |
| } |