/*
* chrt.c - manipulate a task's real-time attributes
*
* 27-Apr-2002: initial version - Robert Love <rml@tech9.net>
* 04-May-2011: make it thread-aware - Davidlohr Bueso <dave@gnu.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2, as
* published by the Free Software Foundation
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Copyright (C) 2004 Robert Love
*/
#include <stdio.h>
#include <stdlib.h>
#include <sched.h>
#include <unistd.h>
#include <getopt.h>
#include <errno.h>
#include "c.h"
#include "nls.h"
#include "closestream.h"
#include "strutils.h"
#include "procutils.h"
/* the SCHED_BATCH is supported since Linux 2.6.16
* -- temporary workaround for people with old glibc headers
*/
#if defined (__linux__) && !defined(SCHED_BATCH)
# define SCHED_BATCH 3
#endif
/* the SCHED_IDLE is supported since Linux 2.6.23
* commit id 0e6aca43e08a62a48d6770e9a159dbec167bf4c6
* -- temporary workaround for people with old glibc headers
*/
#if defined (__linux__) && !defined(SCHED_IDLE)
# define SCHED_IDLE 5
#endif
#if defined(__linux__) && !defined(SCHED_RESET_ON_FORK)
#define SCHED_RESET_ON_FORK 0x40000000
#endif
/* control struct */
struct chrt_ctl {
pid_t pid;
int policy; /* SCHED_* */
int priority;
unsigned int all_tasks : 1, /* all threads of the PID */
reset_on_fork : 1, /* SCHED_RESET_ON_FORK */
altered : 1, /* sched_set**() used */
verbose : 1; /* verbose output */
};
static void __attribute__((__noreturn__)) show_usage(int rc)
{
FILE *out = rc == EXIT_SUCCESS ? stdout : stderr;
fputs(_("Show or change the real-time scheduling attributes of a process.\n"), out);
fputs(USAGE_SEPARATOR, out);
fputs(_("Set policy:\n"
" chrt [options] <priority> <command> [<arg>...]\n"
" chrt [options] -p <priority> <pid>\n"), out);
fputs(USAGE_SEPARATOR, out);
fputs(_("Get policy:\n"
" chrt [options] -p <pid>\n"), out);
fputs(USAGE_SEPARATOR, out);
fputs(_("Policy options:\n"), out);
fputs(_(" -b, --batch set policy to SCHED_BATCH\n"), out);
fputs(_(" -f, --fifo set policy to SCHED_FIFO\n"), out);
fputs(_(" -i, --idle set policy to SCHED_IDLE\n"), out);
fputs(_(" -o, --other set policy to SCHED_OTHER\n"), out);
fputs(_(" -r, --rr set policy to SCHED_RR (default)\n"), out);
#ifdef SCHED_RESET_ON_FORK
fputs(USAGE_SEPARATOR, out);
fputs(_("Scheduling flag:\n"), out);
fputs(_(" -R, --reset-on-fork set SCHED_RESET_ON_FORK for FIFO or RR\n"), out);
#endif
fputs(USAGE_SEPARATOR, out);
fputs(_("Other options:\n"), out);
fputs(_(" -a, --all-tasks operate on all the tasks (threads) for a given pid\n"), out);
fputs(_(" -m, --max show min and max valid priorities\n"), out);
fputs(_(" -p, --pid operate on existing given pid\n"), out);
fputs(_(" -v, --verbose display status information\n"), out);
fputs(USAGE_SEPARATOR, out);
fputs(USAGE_HELP, out);
fputs(USAGE_VERSION, out);
fprintf(out, USAGE_MAN_TAIL("chrt(1)"));
exit(rc);
}
static void show_sched_pid_info(struct chrt_ctl *ctl, pid_t pid)
{
struct sched_param sp;
int policy;
/* don't display "pid 0" as that is confusing */
if (!pid)
pid = getpid();
policy = sched_getscheduler(pid);
if (policy == -1)
err(EXIT_FAILURE, _("failed to get pid %d's policy"), pid);
if (ctl->altered)
printf(_("pid %d's new scheduling policy: "), pid);
else
printf(_("pid %d's current scheduling policy: "), pid);
switch (policy) {
case SCHED_OTHER:
printf("SCHED_OTHER\n");
break;
case SCHED_FIFO:
printf("SCHED_FIFO\n");
break;
#ifdef SCHED_RESET_ON_FORK
case SCHED_FIFO | SCHED_RESET_ON_FORK:
printf("SCHED_FIFO|SCHED_RESET_ON_FORK\n");
break;
#endif
#ifdef SCHED_IDLE
case SCHED_IDLE:
printf("SCHED_IDLE\n");
break;
#endif
case SCHED_RR:
printf("SCHED_RR\n");
break;
#ifdef SCHED_RESET_ON_FORK
case SCHED_RR | SCHED_RESET_ON_FORK:
printf("SCHED_RR|SCHED_RESET_ON_FORK\n");
break;
#endif
#ifdef SCHED_BATCH
case SCHED_BATCH:
printf("SCHED_BATCH\n");
break;
#endif
default:
warnx(_("unknown scheduling policy"));
}
if (sched_getparam(pid, &sp))
err(EXIT_FAILURE, _("failed to get pid %d's attributes"), pid);
if (ctl->altered)
printf(_("pid %d's new scheduling priority: %d\n"),
pid, sp.sched_priority);
else
printf(_("pid %d's current scheduling priority: %d\n"),
pid, sp.sched_priority);
}
static void show_sched_info(struct chrt_ctl *ctl)
{
if (ctl->all_tasks) {
pid_t tid;
struct proc_tasks *ts = proc_open_tasks(ctl->pid);
if (!ts)
err(EXIT_FAILURE, _("cannot obtain the list of tasks"));
while (!proc_next_tid(ts, &tid))
show_sched_pid_info(ctl, tid);
proc_close_tasks(ts);
} else
show_sched_pid_info(ctl, ctl->pid);
}
static void show_min_max(void)
{
unsigned long i;
int policies[] = {
SCHED_OTHER,
SCHED_FIFO,
SCHED_RR,
#ifdef SCHED_BATCH
SCHED_BATCH,
#endif
#ifdef SCHED_IDLE
SCHED_IDLE,
#endif
};
const char *names[] = {
"OTHER",
"FIFO",
"RR",
#ifdef SCHED_BATCH
"BATCH",
#endif
#ifdef SCHED_IDLE
"IDLE",
#endif
};
for (i = 0; i < ARRAY_SIZE(policies); i++) {
int max = sched_get_priority_max(policies[i]);
int min = sched_get_priority_min(policies[i]);
if (max >= 0 && min >= 0)
printf(_("SCHED_%s min/max priority\t: %d/%d\n"),
names[i], min, max);
else
printf(_("SCHED_%s not supported?\n"), names[i]);
}
}
static void set_sched(struct chrt_ctl *ctl)
{
struct sched_param sp = { .sched_priority = ctl->priority };
if (ctl->all_tasks) {
pid_t tid;
struct proc_tasks *ts = proc_open_tasks(ctl->pid);
if (!ts)
err(EXIT_FAILURE, _("cannot obtain the list of tasks"));
while (!proc_next_tid(ts, &tid))
if (sched_setscheduler(tid, ctl->policy, &sp) == -1)
err(EXIT_FAILURE, _("failed to set tid %d's policy"), tid);
proc_close_tasks(ts);
} else if (sched_setscheduler(ctl->pid, ctl->policy, &sp) == -1)
err(EXIT_FAILURE, _("failed to set pid %d's policy"), ctl->pid);
ctl->altered = 1;
}
int main(int argc, char **argv)
{
struct chrt_ctl _ctl = { .pid = -1 }, *ctl = &_ctl;
int c;
static const struct option longopts[] = {
{ "all-tasks", 0, NULL, 'a' },
{ "batch", 0, NULL, 'b' },
{ "fifo", 0, NULL, 'f' },
{ "idle", 0, NULL, 'i' },
{ "pid", 0, NULL, 'p' },
{ "help", 0, NULL, 'h' },
{ "max", 0, NULL, 'm' },
{ "other", 0, NULL, 'o' },
{ "rr", 0, NULL, 'r' },
{ "reset-on-fork", 0, NULL, 'R' },
{ "verbose", 0, NULL, 'v' },
{ "version", 0, NULL, 'V' },
{ NULL, 0, NULL, 0 }
};
setlocale(LC_ALL, "");
bindtextdomain(PACKAGE, LOCALEDIR);
textdomain(PACKAGE);
atexit(close_stdout);
while((c = getopt_long(argc, argv, "+abfiphmoRrvV", longopts, NULL)) != -1)
{
int ret = EXIT_FAILURE;
switch (c) {
case 'a':
ctl->all_tasks = 1;
break;
case 'b':
#ifdef SCHED_BATCH
ctl->policy = SCHED_BATCH;
#endif
break;
case 'f':
ctl->policy = SCHED_FIFO;
break;
case 'R':
ctl->reset_on_fork = 1;
break;
case 'i':
#ifdef SCHED_IDLE
ctl->policy = SCHED_IDLE;
#endif
break;
case 'm':
show_min_max();
return EXIT_SUCCESS;
case 'o':
ctl->policy = SCHED_OTHER;
break;
case 'p':
errno = 0;
ctl->pid = strtos32_or_err(argv[argc - 1], _("invalid PID argument"));
break;
case 'r':
ctl->policy = SCHED_RR;
break;
case 'v':
ctl->verbose = 1;
break;
case 'V':
printf(UTIL_LINUX_VERSION);
return EXIT_SUCCESS;
case 'h':
ret = EXIT_SUCCESS;
/* fallthrough */
default:
show_usage(ret);
}
}
if (((ctl->pid > -1) && argc - optind < 1) ||
((ctl->pid == -1) && argc - optind < 2))
show_usage(EXIT_FAILURE);
if ((ctl->pid > -1) && (ctl->verbose || argc - optind == 1)) {
show_sched_info(ctl);
if (argc - optind == 1)
return EXIT_SUCCESS;
}
errno = 0;
ctl->priority = strtos32_or_err(argv[optind], _("invalid priority argument"));
#ifdef SCHED_RESET_ON_FORK
if (ctl->reset_on_fork) {
if (ctl->policy != SCHED_FIFO && ctl->policy != SCHED_RR)
errx(EXIT_FAILURE, _("SCHED_RESET_ON_FORK flag is supported for "
"SCHED_FIFO and SCHED_RR policies only"));
ctl->policy |= SCHED_RESET_ON_FORK;
}
#endif
if (ctl->pid == -1)
ctl->pid = 0;
set_sched(ctl);
if (ctl->verbose)
show_sched_info(ctl);
if (!ctl->pid) {
argv += optind + 1;
execvp(argv[0], argv);
err(EXIT_FAILURE, _("failed to execute %s"), argv[0]);
}
return EXIT_SUCCESS;
}
