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#include <sched.h>
   9#include "libbb.h"
  10#ifndef _POSIX_PRIORITY_SCHEDULING
  11#warning your system may be foobared
  12#endif
  13
  14static const struct {
  15        int policy;
  16        char name[sizeof("SCHED_OTHER")];
  17} policies[] = {
  18        {SCHED_OTHER, "SCHED_OTHER"},
  19        {SCHED_FIFO, "SCHED_FIFO"},
  20        {SCHED_RR, "SCHED_RR"}
  21};
  22
  23//TODO: add
  24// -b, SCHED_BATCH
  25// -i, SCHED_IDLE
  26
  27static void show_min_max(int pol)
  28{
  29        const char *fmt = "%s min/max priority\t: %u/%u\n";
  30        int max, min;
  31
  32        max = sched_get_priority_max(pol);
  33        min = sched_get_priority_min(pol);
  34        if ((max|min) < 0)
  35                fmt = "%s not supported\n";
  36        printf(fmt, policies[pol].name, min, max);
  37}
  38
  39#define OPT_m (1<<0)
  40#define OPT_p (1<<1)
  41#define OPT_r (1<<2)
  42#define OPT_f (1<<3)
  43#define OPT_o (1<<4)
  44
  45int chrt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  46int chrt_main(int argc UNUSED_PARAM, char **argv)
  47{
  48        pid_t pid = 0;
  49        unsigned opt;
  50        struct sched_param sp;
  51        char *pid_str;
  52        char *priority = priority; /* for compiler */
  53        const char *current_new;
  54        int policy = SCHED_RR;
  55
  56        /* at least 1 arg; only one policy accepted */
  57        opt_complementary = "-1:r--fo:f--ro:r--fo";
  58        opt = getopt32(argv, "+mprfo");
  59        if (opt & OPT_r)
  60                policy = SCHED_RR;
  61        if (opt & OPT_f)
  62                policy = SCHED_FIFO;
  63        if (opt & OPT_o)
  64                policy = SCHED_OTHER;
  65        if (opt & OPT_m) { /* print min/max */
  66                show_min_max(SCHED_FIFO);
  67                show_min_max(SCHED_RR);
  68                show_min_max(SCHED_OTHER);
  69                fflush_stdout_and_exit(EXIT_SUCCESS);
  70        }
  71
  72        argv += optind;
  73        if (opt & OPT_p) {
  74                pid_str = *argv++;
  75                if (*argv) { /* "-p <priority> <pid> [...]" */
  76                        priority = pid_str;
  77                        pid_str = *argv;
  78                }
  79                /* else "-p <pid>", and *argv == NULL */
  80                pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
  81        } else {
  82                priority = *argv++;
  83                if (!*argv)
  84                        bb_show_usage();
  85        }
  86
  87        current_new = "current\0new";
  88        if (opt & OPT_p) {
  89                int pol;
  90 print_rt_info:
  91                pol = sched_getscheduler(pid);
  92                if (pol < 0)
  93                        bb_perror_msg_and_die("can't %cet pid %d's policy", 'g', pid);
  94                printf("pid %d's %s scheduling policy: %s\n",
  95                                pid, current_new, policies[pol].name);
  96                if (sched_getparam(pid, &sp))
  97                        bb_perror_msg_and_die("can't get pid %d's attributes", pid);
  98                printf("pid %d's %s scheduling priority: %d\n",
  99                                pid, current_new, sp.sched_priority);
 100                if (!*argv) {
 101                        /* Either it was just "-p <pid>",
 102                         * or it was "-p <priority> <pid>" and we came here
 103                         * for the second time (see goto below) */
 104                        return EXIT_SUCCESS;
 105                }
 106                *argv = NULL;
 107                current_new += 8;
 108        }
 109
 110        /* from the manpage of sched_getscheduler:
 111        [...] sched_priority can have a value in the range 0 to 99.
 112        [...] SCHED_OTHER or SCHED_BATCH must be assigned static priority 0.
 113        [...] SCHED_FIFO or SCHED_RR can have static priority in 1..99 range.
 114        */
 115        sp.sched_priority = xstrtou_range(priority, 0, policy != SCHED_OTHER ? 1 : 0, 99);
 116
 117        if (sched_setscheduler(pid, policy, &sp) < 0)
 118                bb_perror_msg_and_die("can't %cet pid %d's policy", 's', pid);
 119
 120        if (!argv[0]) /* "-p <priority> <pid> [...]" */
 121                goto print_rt_info;
 122
 123        BB_EXECVP_or_die(argv);
 124}
 125