LXR busybox/util-linux/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//config:config IONICE
  10//config:       bool "ionice (3.8 kb)"
  11//config:       default y
  12//config:       select PLATFORM_LINUX
  13//config:       help
  14//config:       Set/set program io scheduling class and priority
  15//config:       Requires kernel >= 2.6.13
  16
  17//applet:IF_IONICE(APPLET_NOEXEC(ionice, ionice, BB_DIR_BIN, BB_SUID_DROP, ionice))
  18
  19//kbuild:lib-$(CONFIG_IONICE) += ionice.o
  20
  21//usage:#define ionice_trivial_usage
  22//usage:        "[-c 1-3] [-n 0-7] [-p PID] [PROG]"
  23//usage:#define ionice_full_usage "\n\n"
  24//usage:       "Change I/O priority and class\n"
  25//usage:     "\n        -c      Class. 1:realtime 2:best-effort 3:idle"
  26//usage:     "\n        -n      Priority"
  27
  28#include <sys/syscall.h>
  29#include <asm/unistd.h>
  30#include "libbb.h"
  31
  32static int ioprio_set(int which, int who, int ioprio)
  33{
  34        return syscall(SYS_ioprio_set, which, who, ioprio);
  35}
  36
  37static int ioprio_get(int which, int who)
  38{
  39        return syscall(SYS_ioprio_get, which, who);
  40}
  41
  42enum {
  43        IOPRIO_WHO_PROCESS = 1,
  44        IOPRIO_WHO_PGRP,
  45        IOPRIO_WHO_USER
  46};
  47
  48enum {
  49        IOPRIO_CLASS_NONE,
  50        IOPRIO_CLASS_RT,
  51        IOPRIO_CLASS_BE,
  52        IOPRIO_CLASS_IDLE
  53};
  54
  55static const char to_prio[] ALIGN1 = "none\0realtime\0best-effort\0idle";
  56
  57#define IOPRIO_CLASS_SHIFT      13
  58
  59int ionice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  60int ionice_main(int argc UNUSED_PARAM, char **argv)
  61{
  62        /* Defaults */
  63        int ioclass = 0;
  64        int pri = 0;
  65        int pid = 0; /* affect own porcess */
  66        int opt;
  67        enum {
  68                OPT_n = 1,
  69                OPT_c = 2,
  70                OPT_p = 4,
  71        };
  72
  73        /* Numeric params */
  74        /* '+': stop at first non-option */
  75        opt = getopt32(argv, "+n:+c:+p:+", &pri, &ioclass, &pid);
  76        argv += optind;
  77
  78        if (opt & OPT_c) {
  79                if (ioclass > 3)
  80                        bb_error_msg_and_die("bad class %d", ioclass);
  81// Do we need this (compat?)?
  82//              if (ioclass == IOPRIO_CLASS_NONE)
  83//                      ioclass = IOPRIO_CLASS_BE;
  84//              if (ioclass == IOPRIO_CLASS_IDLE) {
  85//                      //if (opt & OPT_n)
  86//                      //      bb_error_msg("ignoring priority for idle class");
  87//                      pri = 7;
  88//              }
  89        }
  90
  91        if (!(opt & (OPT_n|OPT_c))) {
  92                if (!(opt & OPT_p) && *argv)
  93                        pid = xatoi_positive(*argv);
  94
  95                pri = ioprio_get(IOPRIO_WHO_PROCESS, pid);
  96                if (pri == -1)
  97                        bb_perror_msg_and_die("ioprio_%cet", 'g');
  98
  99                ioclass = (pri >> IOPRIO_CLASS_SHIFT) & 0x3;
 100                pri &= 0xff;
 101                printf((ioclass == IOPRIO_CLASS_IDLE) ? "%s\n" : "%s: prio %d\n",
 102                                nth_string(to_prio, ioclass), pri);
 103        } else {
 104//printf("pri=%d class=%d val=%x\n",
 105//pri, ioclass, pri | (ioclass << IOPRIO_CLASS_SHIFT));
 106                pri |= (ioclass << IOPRIO_CLASS_SHIFT);
 107                if (ioprio_set(IOPRIO_WHO_PROCESS, pid, pri) == -1)
 108                        bb_perror_msg_and_die("ioprio_%cet", 's');
 109                if (argv[0]) {
 110                        BB_EXECVP_or_die(argv);
 111                }
 112        }
 113
 114        return EXIT_SUCCESS;
 115}
 116