LXR busybox/miscutils/chrt.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * chrt - manipulate real-time attributes of a process
   4 * Copyright (c) 2006-2007 Bernhard Reutner-Fischer
   5 *
   6 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   7 */
   8
   9#include <sched.h>
  10#include "libbb.h"
  11#ifndef _POSIX_PRIORITY_SCHEDULING
  12#warning your system may be foobared
  13#endif
  14static const struct {
  15        int policy;
  16        char name[12];
  17} policies[] = {
  18        {SCHED_OTHER, "SCHED_OTHER"},
  19        {SCHED_FIFO, "SCHED_FIFO"},
  20        {SCHED_RR, "SCHED_RR"}
  21};
  22
  23static void show_min_max(int pol)
  24{
  25        const char *fmt = "%s min/max priority\t: %d/%d\n\0%s not supported?\n";
  26        int max, min;
  27        max = sched_get_priority_max(pol);
  28        min = sched_get_priority_min(pol);
  29        if (max >= 0 && min >= 0)
  30                printf(fmt, policies[pol].name, min, max);
  31        else {
  32                fmt += 29;
  33                printf(fmt, policies[pol].name);
  34        }
  35}
  36
  37#define OPT_m (1<<0)
  38#define OPT_p (1<<1)
  39#define OPT_r (1<<2)
  40#define OPT_f (1<<3)
  41#define OPT_o (1<<4)
  42
  43int chrt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  44int chrt_main(int argc UNUSED_PARAM, char **argv)
  45{
  46        pid_t pid = 0;
  47        unsigned opt;
  48        struct sched_param sp;
  49        char *pid_str;
  50        char *priority = priority; /* for compiler */
  51        const char *current_new;
  52        int policy = SCHED_RR;
  53
  54        /* at least 1 arg; only one policy accepted */
  55        opt_complementary = "-1:r--fo:f--ro:r--fo";
  56        opt = getopt32(argv, "+mprfo");
  57        if (opt & OPT_r)
  58                policy = SCHED_RR;
  59        if (opt & OPT_f)
  60                policy = SCHED_FIFO;
  61        if (opt & OPT_o)
  62                policy = SCHED_OTHER;
  63        if (opt & OPT_m) { /* print min/max */
  64                show_min_max(SCHED_FIFO);
  65                show_min_max(SCHED_RR);
  66                show_min_max(SCHED_OTHER);
  67                fflush_stdout_and_exit(EXIT_SUCCESS);
  68        }
  69
  70        argv += optind;
  71        if (opt & OPT_p) {
  72                pid_str = *argv++;
  73                if (*argv) { /* "-p <priority> <pid> [...]" */
  74                        priority = pid_str;
  75                        pid_str = *argv;
  76                }
  77                /* else "-p <pid>", and *argv == NULL */
  78                pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
  79        } else {
  80                priority = *argv++;
  81                if (!*argv)
  82                        bb_show_usage();
  83        }
  84
  85        current_new = "current\0new";
  86        if (opt & OPT_p) {
  87                int pol;
  88 print_rt_info:
  89                pol = sched_getscheduler(pid);
  90                if (pol < 0)
  91                        bb_perror_msg_and_die("can't %cet pid %d's policy", 'g', pid);
  92                printf("pid %d's %s scheduling policy: %s\n",
  93                                pid, current_new, policies[pol].name);
  94                if (sched_getparam(pid, &sp))
  95                        bb_perror_msg_and_die("can't get pid %d's attributes", pid);
  96                printf("pid %d's %s scheduling priority: %d\n",
  97                                pid, current_new, sp.sched_priority);
  98                if (!*argv) {
  99                        /* Either it was just "-p <pid>",
 100                         * or it was "-p <priority> <pid>" and we came here
 101                         * for the second time (see goto below) */
 102                        return EXIT_SUCCESS;
 103                }
 104                *argv = NULL;
 105                current_new += 8;
 106        }
 107
 108        /* from the manpage of sched_getscheduler:
 109        [...] sched_priority can have a value in the range 0 to 99.
 110        [...] SCHED_OTHER or SCHED_BATCH must be assigned static priority 0.
 111        [...] SCHED_FIFO or SCHED_RR can have static priority in 1..99 range.
 112        */
 113        sp.sched_priority = xstrtou_range(priority, 0, policy != SCHED_OTHER ? 1 : 0, 99);
 114
 115        if (sched_setscheduler(pid, policy, &sp) < 0)
 116                bb_perror_msg_and_die("can't %cet pid %d's policy", 's', pid);
 117
 118        if (!*argv) /* "-p <priority> <pid> [...]" */
 119                goto print_rt_info;
 120
 121        BB_EXECVP(*argv, argv);
 122        bb_simple_perror_msg_and_die(*argv);
 123}
 124