ioprio.h

   1 #ifndef IOPRIO_H
   2 #define IOPRIO_H
   3
   4 /* This is minimal version of Linux' linux/ioprio.h header file, which
   5  * is licensed GPL2 */
   6
   7 #include <unistd.h>
   8 #include <sys/syscall.h>
   9
  10 /*
  11  * Gives us 8 prio classes with 13-bits of data for each class
  12  */
  13 #define IOPRIO_BITS             (16)
  14 #define IOPRIO_CLASS_SHIFT      (13)
  15 #define IOPRIO_PRIO_MASK        ((1UL << IOPRIO_CLASS_SHIFT) - 1)
  16
  17 #define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT)
  18 #define IOPRIO_PRIO_DATA(mask)  ((mask) & IOPRIO_PRIO_MASK)
  19 #define IOPRIO_PRIO_VALUE(class, data)  (((class) << IOPRIO_CLASS_SHIFT) | data)
  20
  21 #define ioprio_valid(mask)      (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
  22
  23 /*
  24  * These are the io priority groups as implemented by CFQ. RT is the realtime
  25  * class, it always gets premium service. BE is the best-effort scheduling
  26  * class, the default for any process. IDLE is the idle scheduling class, it
  27  * is only served when no one else is using the disk.
  28  */
  29 enum {
  30         IOPRIO_CLASS_NONE,
  31         IOPRIO_CLASS_RT,
  32         IOPRIO_CLASS_BE,
  33         IOPRIO_CLASS_IDLE,
  34 };
  35
  36 /*
  37  * 8 best effort priority levels are supported
  38  */
  39 #define IOPRIO_BE_NR    (8)
  40
  41 enum {
  42         IOPRIO_WHO_PROCESS = 1,
  43         IOPRIO_WHO_PGRP,
  44         IOPRIO_WHO_USER,
  45 };
  46
  47 static inline int ioprio_set(int which, int who, int ioprio)
  48 {
  49         return syscall(__NR_ioprio_set, which, who, ioprio);
  50 }
  51
  52 static inline int ioprio_get(int which, int who)
  53 {
  54         return syscall(__NR_ioprio_get, which, who);
  55 }
  56
  57 #endif