release/src/router/busybox/miscutils/ionice.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * ionice implementation for busybox based on linux-utils-ng 2.14
   4  *
   5  * Copyright (C) 2008 by  <u173034@informatik.uni-oldenburg.de>
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  */
   9
  10 //usage:#define ionice_trivial_usage
  11 //usage:        "[-c 1-3] [-n 0-7] [-p PID] [PROG]"
  12 //usage:#define ionice_full_usage "\n\n"
  13 //usage:       "Change I/O priority and class\n"
  14 //usage:     "\n        -c      Class. 1:realtime 2:best-effort 3:idle"
  15 //usage:     "\n        -n      Priority"
  16
  17 #include <sys/syscall.h>
  18 #include <asm/unistd.h>
  19 #include "libbb.h"
  20
  21 static int ioprio_set(int which, int who, int ioprio)
  22 {
  23         return syscall(SYS_ioprio_set, which, who, ioprio);
  24 }
  25
  26 static int ioprio_get(int which, int who)
  27 {
  28         return syscall(SYS_ioprio_get, which, who);
  29 }
  30
  31 enum {
  32         IOPRIO_WHO_PROCESS = 1,
  33         IOPRIO_WHO_PGRP,
  34         IOPRIO_WHO_USER
  35 };
  36
  37 enum {
  38         IOPRIO_CLASS_NONE,
  39         IOPRIO_CLASS_RT,
  40         IOPRIO_CLASS_BE,
  41         IOPRIO_CLASS_IDLE
  42 };
  43
  44 static const char to_prio[] = "none\0realtime\0best-effort\0idle";
  45
  46 #define IOPRIO_CLASS_SHIFT      13
  47
  48 int ionice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  49 int ionice_main(int argc UNUSED_PARAM, char **argv)
  50 {
  51         /* Defaults */
  52         int ioclass = 0;
  53         int pri = 0;
  54         int pid = 0; /* affect own porcess */
  55         int opt;
  56         enum {
  57                 OPT_n = 1,
  58                 OPT_c = 2,
  59                 OPT_p = 4,
  60         };
  61
  62         /* Numeric params */
  63         opt_complementary = "n+:c+:p+";
  64         /* '+': stop at first non-option */
  65         opt = getopt32(argv, "+n:c:p:", &pri, &ioclass, &pid);
  66         argv += optind;
  67
  68         if (opt & OPT_c) {
  69                 if (ioclass > 3)
  70                         bb_error_msg_and_die("bad class %d", ioclass);
  71 // Do we need this (compat?)?
  72 //              if (ioclass == IOPRIO_CLASS_NONE)
  73 //                      ioclass = IOPRIO_CLASS_BE;
  74 //              if (ioclass == IOPRIO_CLASS_IDLE) {
  75 //                      //if (opt & OPT_n)
  76 //                      //      bb_error_msg("ignoring priority for idle class");
  77 //                      pri = 7;
  78 //              }
  79         }
  80
  81         if (!(opt & (OPT_n|OPT_c))) {
  82                 if (!(opt & OPT_p) && *argv)
  83                         pid = xatoi_positive(*argv);
  84
  85                 pri = ioprio_get(IOPRIO_WHO_PROCESS, pid);
  86                 if (pri == -1)
  87                         bb_perror_msg_and_die("ioprio_%cet", 'g');
  88
  89                 ioclass = (pri >> IOPRIO_CLASS_SHIFT) & 0x3;
  90                 pri &= 0xff;
  91                 printf((ioclass == IOPRIO_CLASS_IDLE) ? "%s\n" : "%s: prio %d\n",
  92                                 nth_string(to_prio, ioclass), pri);
  93         } else {
  94 //printf("pri=%d class=%d val=%x\n",
  95 //pri, ioclass, pri | (ioclass << IOPRIO_CLASS_SHIFT));
  96                 pri |= (ioclass << IOPRIO_CLASS_SHIFT);
  97                 if (ioprio_set(IOPRIO_WHO_PROCESS, pid, pri) == -1)
  98                         bb_perror_msg_and_die("ioprio_%cet", 's');
  99                 if (argv[0]) {
 100                         BB_EXECVP_or_die(argv);
 101                 }
 102         }
 103
 104         return EXIT_SUCCESS;
 105 }