source: branches/3.2/mindi-busybox/miscutils/chrt.c @ 3232

Last change on this file since 3232 was 3232, checked in by bruno, 5 years ago
  • Update mindi-busybox to 1.21.1
  • Property svn:eol-style set to native
File size: 3.8 KB
Line 
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 source tree.
7 */
8
9//usage:#define chrt_trivial_usage
10//usage:       "[-prfom] [PRIO] [PID | PROG ARGS]"
11//usage:#define chrt_full_usage "\n\n"
12//usage:       "Change scheduling priority and class for a process\n"
13//usage:     "\n    -p  Operate on PID"
14//usage:     "\n    -r  Set SCHED_RR class"
15//usage:     "\n    -f  Set SCHED_FIFO class"
16//usage:     "\n    -o  Set SCHED_OTHER class"
17//usage:     "\n    -m  Show min/max priorities"
18//usage:
19//usage:#define chrt_example_usage
20//usage:       "$ chrt -r 4 sleep 900; x=$!\n"
21//usage:       "$ chrt -f -p 3 $x\n"
22//usage:       "You need CAP_SYS_NICE privileges to set scheduling attributes of a process"
23
24#include <sched.h>
25#include "libbb.h"
26#ifndef _POSIX_PRIORITY_SCHEDULING
27#warning your system may be foobared
28#endif
29
30static const struct {
31    int policy;
32    char name[sizeof("SCHED_OTHER")];
33} policies[] = {
34    {SCHED_OTHER, "SCHED_OTHER"},
35    {SCHED_FIFO, "SCHED_FIFO"},
36    {SCHED_RR, "SCHED_RR"}
37};
38
39//TODO: add
40// -b, SCHED_BATCH
41// -i, SCHED_IDLE
42
43static void show_min_max(int pol)
44{
45    const char *fmt = "%s min/max priority\t: %u/%u\n";
46    int max, min;
47
48    max = sched_get_priority_max(pol);
49    min = sched_get_priority_min(pol);
50    if ((max|min) < 0)
51        fmt = "%s not supported\n";
52    printf(fmt, policies[pol].name, min, max);
53}
54
55#define OPT_m (1<<0)
56#define OPT_p (1<<1)
57#define OPT_r (1<<2)
58#define OPT_f (1<<3)
59#define OPT_o (1<<4)
60
61int chrt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
62int chrt_main(int argc UNUSED_PARAM, char **argv)
63{
64    pid_t pid = 0;
65    unsigned opt;
66    struct sched_param sp;
67    char *pid_str;
68    char *priority = priority; /* for compiler */
69    const char *current_new;
70    int policy = SCHED_RR;
71
72    /* only one policy accepted */
73    opt_complementary = "r--fo:f--ro:o--rf";
74    opt = getopt32(argv, "+mprfo");
75    if (opt & OPT_m) { /* print min/max and exit */
76        show_min_max(SCHED_FIFO);
77        show_min_max(SCHED_RR);
78        show_min_max(SCHED_OTHER);
79        fflush_stdout_and_exit(EXIT_SUCCESS);
80    }
81    if (opt & OPT_r)
82        policy = SCHED_RR;
83    if (opt & OPT_f)
84        policy = SCHED_FIFO;
85    if (opt & OPT_o)
86        policy = SCHED_OTHER;
87
88    argv += optind;
89    if (!argv[0])
90        bb_show_usage();
91    if (opt & OPT_p) {
92        pid_str = *argv++;
93        if (*argv) { /* "-p <priority> <pid> [...]" */
94            priority = pid_str;
95            pid_str = *argv;
96        }
97        /* else "-p <pid>", and *argv == NULL */
98        pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
99    } else {
100        priority = *argv++;
101        if (!*argv)
102            bb_show_usage();
103    }
104
105    current_new = "current\0new";
106    if (opt & OPT_p) {
107        int pol;
108 print_rt_info:
109        pol = sched_getscheduler(pid);
110        if (pol < 0)
111            bb_perror_msg_and_die("can't %cet pid %d's policy", 'g', (int)pid);
112        printf("pid %d's %s scheduling policy: %s\n",
113                pid, current_new, policies[pol].name);
114        if (sched_getparam(pid, &sp))
115            bb_perror_msg_and_die("can't get pid %d's attributes", (int)pid);
116        printf("pid %d's %s scheduling priority: %d\n",
117                (int)pid, current_new, sp.sched_priority);
118        if (!*argv) {
119            /* Either it was just "-p <pid>",
120             * or it was "-p <priority> <pid>" and we came here
121             * for the second time (see goto below) */
122            return EXIT_SUCCESS;
123        }
124        *argv = NULL;
125        current_new += 8;
126    }
127
128    /* from the manpage of sched_getscheduler:
129    [...] sched_priority can have a value in the range 0 to 99.
130    [...] SCHED_OTHER or SCHED_BATCH must be assigned static priority 0.
131    [...] SCHED_FIFO or SCHED_RR can have static priority in 1..99 range.
132    */
133    sp.sched_priority = xstrtou_range(priority, 0, policy != SCHED_OTHER ? 1 : 0, 99);
134
135    if (sched_setscheduler(pid, policy, &sp) < 0)
136        bb_perror_msg_and_die("can't %cet pid %d's policy", 's', (int)pid);
137
138    if (!argv[0]) /* "-p <priority> <pid> [...]" */
139        goto print_rt_info;
140
141    BB_EXECVP_or_die(argv);
142}
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