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
  18 static inline int ioprio_set(int which, int who, int ioprio)
  19 {
  20         return syscall(SYS_ioprio_set, which, who, ioprio);
  21 }
  22
  23 static inline int ioprio_get(int which, int who)
  24 {
  25         return syscall(SYS_ioprio_get, which, who);
  26 }
  27
  28 enum {
  29         IOPRIO_CLASS_NONE,
  30         IOPRIO_CLASS_RT,
  31         IOPRIO_CLASS_BE,
  32         IOPRIO_CLASS_IDLE,
  33 };
  34
  35 enum {
  36         IOPRIO_WHO_PROCESS = 1,
  37         IOPRIO_WHO_PGRP,
  38         IOPRIO_WHO_USER,
  39 };
  40
  41 #define IOPRIO_CLASS_SHIFT      13
  42
  43 const char *to_prio[] = { "none", "realtime", "best-effort", "idle", };
  44
  45 static void usage(void)
  46 {
  47         printf("Usage: ionice [OPTIONS] [COMMAND [ARG]...]\n");
  48         printf("Sets or gets process io scheduling class and priority.\n");
  49         printf("\n\t-n\tClass data (typically 0-7, lower being higher prio)\n");
  50         printf("\t-c\tScheduling class\n");
  51         printf("\t\t\t1: realtime, 2: best-effort, 3: idle\n");
  52         printf("\t-p\tProcess pid\n");
  53         printf("\t-t\tIgnore failures to set priority, run command unconditionally\n");
  54         printf("\t-h\tThis help page\n");
  55         printf("\nJens Axboe <axboe@suse.de> (C) 2005\n");
  56 }
  57
  58 int main(int argc, char *argv[])
  59 {
  60         int ioprio = 4, set = 0, tolerant = 0, ioprio_class = IOPRIO_CLASS_BE;
  61         int c, pid = 0;
  62
  63         while ((c = getopt(argc, argv, "+n:c:p:th")) != EOF) {
  64                 switch (c) {
  65                 case 'n':
  66                         ioprio = strtol(optarg, NULL, 10);
  67                         set |= 1;
  68                         break;
  69                 case 'c':
  70                         ioprio_class = strtol(optarg, NULL, 10);
  71                         set |= 2;
  72                         break;
  73                 case 'p':
  74                         pid = strtol(optarg, NULL, 10);
  75                         break;
  76                 case 't':
  77                         tolerant = 1;
  78                         break;
  79                 case 'h':
  80                 default:
  81                         usage();
  82                         exit(EXIT_SUCCESS);
  83                 }
  84         }
  85
  86         switch (ioprio_class) {
  87                 case IOPRIO_CLASS_NONE:
  88                         ioprio_class = IOPRIO_CLASS_BE;
  89                         break;
  90                 case IOPRIO_CLASS_RT:
  91                 case IOPRIO_CLASS_BE:
  92                         break;
  93                 case IOPRIO_CLASS_IDLE:
  94                         if (set & 1)
  95                                 printf("Ignoring given class data for idle class\n");
  96                         ioprio = 7;
  97                         break;
  98                 default:
  99                         printf("bad prio class %d\n", ioprio_class);
 100                         exit(EXIT_FAILURE);
 101         }
 102
 103         if (!set) {
 104                 if (!pid && argv[optind])
 105                         pid = strtol(argv[optind], NULL, 10);
 106
 107                 ioprio = ioprio_get(IOPRIO_WHO_PROCESS, pid);
 108
 109                 if (ioprio == -1) {
 110                         perror("ioprio_get");
 111                         exit(EXIT_FAILURE);
 112                 } else {
 113                         ioprio_class = ioprio >> IOPRIO_CLASS_SHIFT;
 114                         if (ioprio_class != IOPRIO_CLASS_IDLE) {
 115                                 ioprio = ioprio & 0xff;
 116                                 printf("%s: prio %d\n", to_prio[ioprio_class], ioprio);
 117                         } else
 118                                 printf("%s\n", to_prio[ioprio_class]);
 119                 }
 120         } else {
 121                 if (ioprio_set(IOPRIO_WHO_PROCESS, pid, ioprio | ioprio_class << IOPRIO_CLASS_SHIFT) == -1) {
 122                         if (!tolerant) {
 123                                 perror("ioprio_set");
 124                                 exit(EXIT_FAILURE);
 125                         }
 126                 }
 127
 128                 if (argv[optind]) {
 129                         execvp(argv[optind], &argv[optind]);
 130                         /* execvp should never return */
 131                         perror("execvp");
 132                         exit(EXIT_FAILURE);
 133                 }
 134         }
 135
 136         exit(EXIT_SUCCESS);
 137 }