glue/ioprio-glue.c

   1 /*
   2  * ioprio-glue.c - I/O priority wrappers for the big dog
   3  *
   4  * Robert Love  <rml@novell.com>
   5  *
   6  * Copyright (C) 2005 Novell, Inc.
   7  */
   8
   9 #if defined(__i386__)
  10 #define __NR_ioprio_set         289
  11 #define __NR_ioprio_get         290
  12 #elif defined(__powerpc__) || defined(__powerpc64__)
  13 #define __NR_ioprio_set         273
  14 #define __NR_ioprio_get         274
  15 #elif defined(__x86_64__)
  16 #define __NR_ioprio_set         251
  17 #define __NR_ioprio_get         252
  18 #elif defined(__ia64__)
  19 #define __NR_ioprio_set         1274
  20 #define __NR_ioprio_get         1275
  21 #elif defined(__alpha__)
  22 #define __NR_ioprio_set         442
  23 #define __NR_ioprio_get         443
  24 #elif defined(__s390x__) || defined(__s390__)
  25 #define __NR_ioprio_set         282
  26 #define __NR_ioprio_get         283
  27 #elif defined(__SH4__)
  28 #define __NR_ioprio_set         288
  29 #define __NR_ioprio_get         289
  30 #elif defined(__SH5__)
  31 #define __NR_ioprio_set         316
  32 #define __NR_ioprio_get         317
  33 #elif defined(__sparc__) || defined(__sparc64__)
  34 #define __NR_ioprio_set         196
  35 #define __NR_ioprio_get         218
  36 #elif defined(__arm__)
  37 #define __NR_ioprio_set         314
  38 #define __NR_ioprio_get         315
  39 #else
  40 #error "Unsupported architecture!"
  41 #endif
  42
  43 static inline int ioprio_set (int which, int who, int ioprio)
  44 {
  45         return syscall (__NR_ioprio_set, which, who, ioprio);
  46 }
  47
  48 static inline int ioprio_get (int which, int who)
  49 {
  50         return syscall (__NR_ioprio_get, which, who);
  51 }
  52
  53 enum {
  54         IOPRIO_CLASS_NONE,
  55         IOPRIO_CLASS_RT,
  56         IOPRIO_CLASS_BE,
  57         IOPRIO_CLASS_IDLE,
  58 };
  59
  60 enum {
  61         IOPRIO_WHO_PROCESS = 1,
  62         IOPRIO_WHO_PGRP,
  63         IOPRIO_WHO_USER,
  64 };
  65
  66 #define IOPRIO_CLASS_SHIFT      13
  67 #define IOPRIO_PRIO_MASK        0xff
  68
  69 int set_io_priority_idle (void)
  70 {
  71         int ioprio, ioclass;
  72
  73         ioprio = 7; /* priority is ignored with idle class */
  74         ioclass = IOPRIO_CLASS_IDLE << IOPRIO_CLASS_SHIFT;
  75
  76         return ioprio_set (IOPRIO_WHO_PROCESS, 0, ioprio | ioclass);
  77 }