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:       help
  13//config:       Set/set program io scheduling class and priority
  14//config:       Requires kernel >= 2.6.13
  15
  16//applet:IF_IONICE(APPLET_NOEXEC(ionice, ionice, BB_DIR_BIN, BB_SUID_DROP, ionice))
  17
  18//kbuild:lib-$(CONFIG_IONICE) += ionice.o
  19
  20//usage:#define ionice_trivial_usage
  21//usage:        "[-c 1-3] [-n 0-7] [-t] { -p PID | PROG ARGS }"
  22//TODO: | -P PGID | -u UID; also -pPu can take _list of_ IDs
  23//usage:#define ionice_full_usage "\n\n"
  24//usage:       "Change I/O priority and class\n"
  25//usage:     "\n        -c N    Class. 1:realtime 2:best-effort 3:idle"
  26//usage:     "\n        -n N    Priority"
  27//usage:     "\n        -t      Ignore errors"
  28
  29#include <sys/syscall.h>
  30#include <asm/unistd.h>
  31#include "libbb.h"
  32
  33static int ioprio_set(int which, int who, int ioprio)
  34{
  35        return syscall(SYS_ioprio_set, which, who, ioprio);
  36}
  37
  38static int ioprio_get(int which, int who)
  39{
  40        return syscall(SYS_ioprio_get, which, who);
  41}
  42
  43enum {
  44        IOPRIO_WHO_PROCESS = 1,
  45        IOPRIO_WHO_PGRP,
  46        IOPRIO_WHO_USER
  47};
  48
  49enum {
  50        IOPRIO_CLASS_NONE,
  51        IOPRIO_CLASS_RT,
  52        IOPRIO_CLASS_BE,
  53        IOPRIO_CLASS_IDLE
  54};
  55
  56static const char to_prio[] ALIGN1 = "none\0realtime\0best-effort\0idle";
  57
  58#define IOPRIO_CLASS_SHIFT      13
  59
  60int ionice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  61int ionice_main(int argc UNUSED_PARAM, char **argv)
  62{
  63        /* Defaults */
  64        int ioclass = 0;
  65        int pri = 0;
  66        int pid = 0; /* affect own process */
  67        int opt;
  68        enum {
  69                OPT_n = 1 << 0,
  70                OPT_c = 1 << 1,
  71                OPT_p = 1 << 2,
  72                OPT_t = 1 << 3,
  73        };
  74
  75        /* '+': stop at first non-option */
  76        /* numeric params for -n -c -p */
  77        opt = getopt32(argv, "+""n:+c:+p:+t", &pri, &ioclass, &pid);
  78        argv += optind;
  79
  80        if (opt & OPT_c) {
  81                if (ioclass > 3)
  82                        bb_error_msg_and_die("bad class %d", ioclass);
  83// Do we need this (compat?)?
  84//              if (ioclass == IOPRIO_CLASS_NONE)
  85//                      ioclass = IOPRIO_CLASS_BE;
  86//              if (ioclass == IOPRIO_CLASS_IDLE) {
  87//                      //if (opt & OPT_n)
  88//                      //      bb_error_msg("ignoring priority for idle class");
  89//                      pri = 7;
  90//              }
  91        }
  92
  93        if (!(opt & (OPT_n|OPT_c))) {
  94                if (!(opt & OPT_p) && *argv)
  95                        pid = xatoi_positive(*argv);
  96
  97                pri = ioprio_get(IOPRIO_WHO_PROCESS, pid);
  98                if (pri == -1)
  99                        bb_perror_msg_and_die("ioprio_%cet", 'g');
 100
 101                ioclass = (pri >> IOPRIO_CLASS_SHIFT) & 0x3;
 102                pri &= 0xff;
 103                printf((ioclass == IOPRIO_CLASS_IDLE) ? "%s\n" : "%s: prio %d\n",
 104                                nth_string(to_prio, ioclass), pri);
 105        } else {
 106//printf("pri=%d class=%d val=%x\n",
 107//pri, ioclass, pri | (ioclass << IOPRIO_CLASS_SHIFT));
 108                pri |= (ioclass << IOPRIO_CLASS_SHIFT);
 109                if (ioprio_set(IOPRIO_WHO_PROCESS, pid, pri) == -1)
 110                        if (!(opt & OPT_t))
 111                                bb_perror_msg_and_die("ioprio_%cet", 's');
 112                if (argv[0]) {
 113                        BB_EXECVP_or_die(argv);
 114                }
 115        }
 116
 117        return EXIT_SUCCESS;
 118}
 119