/*
* chrt.c - chrt
* Command-line utility for manipulating a task's real-time attributes
*
* Robert Love <rml@tech9.net>
* 27-Apr-2002: initial version
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, v2, 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Copyright (C) 2004 Robert Love
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <sched.h>
#include <unistd.h>
#include <getopt.h>
#include <errno.h>
static void show_usage(const char *cmd)
{
fprintf(stderr, "chrt (%s)\n", PACKAGE_STRING);
fprintf(stderr, "usage: %s [options] [prio] [pid | cmd [args...]]\n",
cmd);
fprintf(stderr, "manipulate real-time attributes of a process\n");
fprintf(stderr, " -b, --batch "
"set policy to SCHED_BATCH\n");
fprintf(stderr, " -f, --fifo "
"set policy to SCHED_FF\n");
fprintf(stderr, " -p, --pid "
"operate on existing given pid\n");
fprintf(stderr, " -m, --max "
"show min and max valid priorities\n");
fprintf(stderr, " -o, --other "
"set policy to SCHED_OTHER\n");
fprintf(stderr, " -r, --rr "
"set policy to SCHED_RR (default)\n");
fprintf(stderr, " -h, --help "
"display this help\n");
fprintf(stderr, " -v, --verbose "
"display status information\n");
fprintf(stderr, " -V, --version "
"output version information\n\n");
fprintf(stderr, "You must give a priority if changing policy.\n\n");
fprintf(stderr, "Report bugs and send patches to <rml@tech9.net>\n");
}
static void show_rt_info(const char *what, 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) {
perror("sched_getscheduler");
fprintf(stderr, "failed to get pid %d's policy\n", pid);
exit(1);
}
printf("pid %d's %s scheduling policy: ", pid, what);
switch (policy) {
case SCHED_OTHER:
printf("SCHED_OTHER\n");
break;
case SCHED_FIFO:
printf("SCHED_FIFO\n");
break;
case SCHED_RR:
printf("SCHED_RR\n");
break;
case SCHED_BATCH:
printf("SCHED_BATCH\n");
break;
default:
printf("unknown\n");
}
if (sched_getparam(pid, &sp)) {
perror("sched_getparam");
fprintf(stderr, "failed to get pid %d's attributes\n", pid);
exit(1);
}
printf("pid %d's %s scheduling priority: %d\n",
pid, what, sp.sched_priority);
}
static void show_min_max(void)
{
int max, min;
max = sched_get_priority_max(SCHED_OTHER);
min = sched_get_priority_min(SCHED_OTHER);
if (max >= 0 && min >= 0)
printf("SCHED_OTHER min/max priority\t: %d/%d\n", min, max);
else
printf("SCHED_OTHER not supported?\n");
max = sched_get_priority_max(SCHED_FIFO);
min = sched_get_priority_min(SCHED_FIFO);
if (max >= 0 && min >= 0)
printf("SCHED_FIFO min/max priority\t: %d/%d\n", min, max);
else
printf("SCHED_FIFO not supported?\n");
max = sched_get_priority_max(SCHED_RR);
min = sched_get_priority_min(SCHED_RR);
if (max >= 0 && min >= 0)
printf("SCHED_RR min/max priority\t: %d/%d\n", min, max);
else
printf("SCHED_RR not supported?\n");
max = sched_get_priority_max(SCHED_BATCH);
min = sched_get_priority_min(SCHED_BATCH);
if (max >= 0 && min >= 0)
printf("SCHED_BATCH min/max priority\t: %d/%d\n", min, max);
else
printf("SCHED_BATCH not supported?\n");
}
int main(int argc, char *argv[])
{
int i, policy = SCHED_RR, priority = 0, verbose = 0;
struct sched_param sp;
pid_t pid = 0;
struct option longopts[] = {
{ "batch", 0, NULL, 'b' },
{ "fifo", 0, NULL, 'f' },
{ "pid", 0, NULL, 'p' },
{ "help", 0, NULL, 'h' },
{ "max", 0, NULL, 'm' },
{ "other", 0, NULL, 'o' },
{ "rr", 0, NULL, 'r' },
{ "verbose", 0, NULL, 'v' },
{ "version", 0, NULL, 'V' },
{ NULL, 0, NULL, 0 }
};
while((i = getopt_long(argc, argv, "+bfphmorvV", longopts, NULL)) != -1)
{
int ret = 1;
switch (i) {
case 'b':
policy = SCHED_BATCH;
break;
case 'f':
policy = SCHED_FIFO;
break;
case 'm':
show_min_max();
return 0;
case 'o':
policy = SCHED_OTHER;
break;
case 'p':
errno = 0;
pid = strtol(argv[argc - 1], NULL, 10);
if (errno) {
perror("strtol");
fprintf(stderr, "failed to parse pid!\n");
return 1;
}
break;
case 'r':
policy = SCHED_RR;
break;
case 'v':
verbose = 1;
break;
case 'V':
printf("chrt (%s)\n", PACKAGE_STRING);
return 0;
case 'h':
ret = 0;
default:
show_usage(argv[0]);
return ret;
}
}
if ((pid && argc - optind < 1) || (!pid && argc - optind < 2)) {
show_usage(argv[0]);
return 1;
}
if (pid && (verbose || argc - optind == 1)) {
show_rt_info("current", pid);
if (argc - optind == 1)
return 0;
}
errno = 0;
priority = strtol(argv[optind], NULL, 10);
if (errno) {
perror("strtol");
fprintf(stderr, "failed to parse priority!\n");
return 1;
}
sp.sched_priority = priority;
if (sched_setscheduler(pid, policy, &sp) == -1) {
perror("sched_setscheduler");
fprintf(stderr, "failed to set pid %d's policy\n", pid);
return 1;
}
if (verbose)
show_rt_info("new", pid);
if (!pid) {
argv += optind + 1;
execvp(argv[0], argv);
perror("execvp");
fprintf(stderr, "failed to execute %s\n", argv[0]);
return 1;
}
return 0;
}
