schedutils/ionice.c

   1 /*
   2  * ionice: set or get process io scheduling class and priority
   3  *
   4  * Copyright (C) 2005 Jens Axboe <axboe@suse.de> SUSE Labs
   5  *
   6  * Released under the terms of the GNU General Public License version 2
   7  *
   8  */
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <errno.h>
  12 #include <getopt.h>
  13 #include <unistd.h>
  14 #include <sys/ptrace.h>
  15 #include <sys/syscall.h>
  16 #include <asm/unistd.h>
  17 #include <err.h>
  18
  19 #include "nls.h"
  20
  21 static inline int ioprio_set(int which, int who, int ioprio)
  22 {
  23         return syscall(SYS_ioprio_set, which, who, ioprio);
  24 }
  25
  26 static inline int ioprio_get(int which, int who)
  27 {
  28         return syscall(SYS_ioprio_get, which, who);
  29 }
  30
  31 enum {
  32         IOPRIO_CLASS_NONE,
  33         IOPRIO_CLASS_RT,
  34         IOPRIO_CLASS_BE,
  35         IOPRIO_CLASS_IDLE,
  36 };
  37
  38 enum {
  39         IOPRIO_WHO_PROCESS = 1,
  40         IOPRIO_WHO_PGRP,
  41         IOPRIO_WHO_USER,
  42 };
  43
  44 #define IOPRIO_CLASS_SHIFT      13
  45
  46 const char *to_prio[] = { "none", "realtime", "best-effort", "idle", };
  47
  48 static void usage(int rc)
  49 {
  50         fprintf(stdout, _(
  51         "\nionice - sets or gets process io scheduling class and priority.\n\n"
  52         "Usage: ionice [OPTIONS] [COMMAND [ARG]...]\n\n"
  53         "  -n <classdata>      class data (0-7, lower being higher prio)\n"
  54         "  -c <class>          scheduling class\n"
  55         "                      1: realtime, 2: best-effort, 3: idle\n"
  56         "  -p <pid>            process pid\n"
  57         "  -t                  ignore failures, run command unconditionally\n"
  58         "  -h                  this help\n\n"));
  59
  60         exit(rc);
  61 }
  62
  63 int main(int argc, char *argv[])
  64 {
  65         int ioprio = 4, set = 0, tolerant = 0, ioprio_class = IOPRIO_CLASS_BE;
  66         int c, pid = 0;
  67
  68         setlocale(LC_ALL, "");
  69         bindtextdomain(PACKAGE, LOCALEDIR);
  70         textdomain(PACKAGE);
  71
  72         while ((c = getopt(argc, argv, "+n:c:p:th")) != EOF) {
  73                 switch (c) {
  74                 case 'n':
  75                         ioprio = strtol(optarg, NULL, 10);
  76                         set |= 1;
  77                         break;
  78                 case 'c':
  79                         ioprio_class = strtol(optarg, NULL, 10);
  80                         set |= 2;
  81                         break;
  82                 case 'p':
  83                         pid = strtol(optarg, NULL, 10);
  84                         break;
  85                 case 't':
  86                         tolerant = 1;
  87                         break;
  88                 case 'h':
  89                         usage(EXIT_SUCCESS);
  90                 default:
  91                         usage(EXIT_FAILURE);
  92                 }
  93         }
  94
  95         switch (ioprio_class) {
  96                 case IOPRIO_CLASS_NONE:
  97                         ioprio_class = IOPRIO_CLASS_BE;
  98                         break;
  99                 case IOPRIO_CLASS_RT:
 100                 case IOPRIO_CLASS_BE:
 101                         break;
 102                 case IOPRIO_CLASS_IDLE:
 103                         if (set & 1)
 104                                 warnx(_("ignoring given class data for idle class"));
 105                         ioprio = 7;
 106                         break;
 107                 default:
 108                         errx(EXIT_FAILURE, _("bad prio class %d"), ioprio_class);
 109         }
 110
 111         if (!set) {
 112                 if (!pid && argv[optind])
 113                         pid = strtol(argv[optind], NULL, 10);
 114
 115                 ioprio = ioprio_get(IOPRIO_WHO_PROCESS, pid);
 116
 117                 if (ioprio == -1)
 118                         err(EXIT_FAILURE, _("ioprio_get failed"));
 119                 else {
 120                         ioprio_class = ioprio >> IOPRIO_CLASS_SHIFT;
 121                         if (ioprio_class != IOPRIO_CLASS_IDLE) {
 122                                 ioprio = ioprio & 0xff;
 123                                 printf("%s: prio %d\n", to_prio[ioprio_class], ioprio);
 124                         } else
 125                                 printf("%s\n", to_prio[ioprio_class]);
 126                 }
 127         } else {
 128                 if (ioprio_set(IOPRIO_WHO_PROCESS, pid, ioprio | ioprio_class << IOPRIO_CLASS_SHIFT) == -1) {
 129                         if (!tolerant)
 130                                 err(EXIT_FAILURE, _("ioprio_set failed"));
 131                 }
 132
 133                 if (argv[optind]) {
 134                         execvp(argv[optind], &argv[optind]);
 135                         /* execvp should never return */
 136                         err(EXIT_FAILURE, _("execvp failed"));
 137                 }
 138         }
 139
 140         exit(EXIT_SUCCESS);
 141 }