LXR toybox/toys/other/ionice.c

   1/* ionice.c - set or get process I/O scheduling class and priority
   2 *
   3 * Copyright 2015 Rob Landley <rob@landley.net>
   4 *
   5 * It would be really nice if there was a standard, but no. There is
   6 * Documentation/block/ioprio.txt in the linux source.
   7
   8USE_IONICE(NEWTOY(ionice, "^tc#<0>3=2n#<0>7=5p#", TOYFLAG_USR|TOYFLAG_BIN))
   9USE_IORENICE(NEWTOY(iorenice, "<1>3", TOYFLAG_USR|TOYFLAG_BIN))
  10
  11config IONICE
  12  bool "ionice"
  13  default y
  14  help
  15    usage: ionice [-t] [-c CLASS] [-n LEVEL] [COMMAND...|-p PID]
  16
  17    Change the I/O scheduling priority of a process. With no arguments
  18    (or just -p), display process' existing I/O class/priority.
  19
  20    -c  CLASS = 1-3: 1(realtime), 2(best-effort, default), 3(when-idle)
  21    -n  LEVEL = 0-7: (0 is highest priority, default = 5)
  22    -p  Affect existing PID instead of spawning new child
  23    -t  Ignore failure to set I/O priority
  24
  25    System default iopriority is generally -c 2 -n 4.
  26
  27config IORENICE
  28  bool "iorenice"
  29  default y
  30  help
  31    usage: iorenice PID [CLASS] [PRIORITY]
  32
  33    Display or change I/O priority of existing process. CLASS can be
  34    "rt" for realtime, "be" for best effort, "idle" for only when idle, or
  35    "none" to leave it alone. PRIORITY can be 0-7 (0 is highest, default 4).
  36*/
  37
  38#define FOR_ionice
  39#include "toys.h"
  40
  41GLOBALS(
  42  long p, n, c;
  43)
  44
  45static int ioprio_get(void)
  46{
  47  return syscall(__NR_ioprio_get, 1, (int)TT.p);
  48}
  49
  50static int ioprio_set(void)
  51{
  52  int prio = ((int)TT.c << 13) | (int)TT.n;
  53
  54  return syscall(__NR_ioprio_set, 1, (int)TT.p, prio);
  55}
  56
  57void ionice_main(void)
  58{
  59  if (!TT.p && !toys.optc) error_exit("Need -p or COMMAND");
  60  if (toys.optflags == FLAG_p) {
  61    int p = ioprio_get();
  62
  63    xprintf("%s: prio %d\n",
  64      (char *[]){"unknown", "Realtime", "Best-effort", "Idle"}[(p>>13)&3],
  65      p&7);
  66  } else {
  67    if (-1 == ioprio_set() && !FLAG(t)) perror_exit("set");
  68    if (!TT.p) xexec(toys.optargs);
  69  }
  70}
  71
  72void iorenice_main(void)
  73{
  74  char *classes[] = {"none", "rt", "be", "idle"};
  75
  76  TT.p = atolx(*toys.optargs);
  77  if (toys.optc == 1) {
  78    int p = ioprio_get();
  79
  80    if (p == -1) perror_exit("read priority");
  81    TT.c = (p>>13)&3;
  82    p &= 7;
  83    xprintf("Pid %ld, class %s (%ld), prio %d\n", TT.p, classes[TT.c], TT.c, p);
  84    return;
  85  }
  86
  87  for (TT.c = 0; TT.c<4; TT.c++)
  88    if (!strcmp(toys.optargs[toys.optc-1], classes[TT.c])) break;
  89  if (toys.optc == 3 || TT.c == 4) TT.n = atolx(toys.optargs[1]);
  90  else TT.n = 4;
  91  TT.c &= 3;
  92
  93  if (-1 == ioprio_set()) perror_exit("set");
  94}
  95