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 #include <sys/syscall.h>
  10 #include <unistd.h>
  11
  12 #if defined(__i386__)
  13 #define __NR_ioprio_set         289
  14 #define __NR_ioprio_get         290
  15 #elif defined(__powerpc__) || defined(__powerpc64__)
  16 #define __NR_ioprio_set         273
  17 #define __NR_ioprio_get         274
  18 #elif defined(__x86_64__)
  19 #define __NR_ioprio_set         251
  20 #define __NR_ioprio_get         252
  21 #elif defined(__ia64__)
  22 #define __NR_ioprio_set         1274
  23 #define __NR_ioprio_get         1275
  24 #elif defined(__alpha__)
  25 #define __NR_ioprio_set         442
  26 #define __NR_ioprio_get         443
  27 #elif defined(__s390x__) || defined(__s390__)
  28 #define __NR_ioprio_set         282
  29 #define __NR_ioprio_get         283
  30 #elif defined(__SH4__)
  31 #define __NR_ioprio_set         288
  32 #define __NR_ioprio_get         289
  33 #elif defined(__SH5__)
  34 #define __NR_ioprio_set         316
  35 #define __NR_ioprio_get         317
  36 #elif defined(__sparc__) || defined(__sparc64__)
  37 #define __NR_ioprio_set         196
  38 #define __NR_ioprio_get         218
  39 #elif defined(__arm__)
  40 #define __NR_ioprio_set         314
  41 #define __NR_ioprio_get         315
  42 #else
  43 #error "Unsupported architecture!"
  44 #endif
  45
  46 static inline int ioprio_set (int which, int who, int ioprio)
  47 {
  48         return syscall (__NR_ioprio_set, which, who, ioprio);
  49 }
  50
  51 static inline int ioprio_get (int which, int who)
  52 {
  53         return syscall (__NR_ioprio_get, which, who);
  54 }
  55
  56 enum {
  57         IOPRIO_CLASS_NONE,
  58         IOPRIO_CLASS_RT,
  59         IOPRIO_CLASS_BE,
  60         IOPRIO_CLASS_IDLE,
  61 };
  62
  63 enum {
  64         IOPRIO_WHO_PROCESS = 1,
  65         IOPRIO_WHO_PGRP,
  66         IOPRIO_WHO_USER,
  67 };
  68
  69 #define IOPRIO_CLASS_SHIFT      13
  70 #define IOPRIO_PRIO_MASK        0xff
  71
  72 int set_io_priority_idle (void)
  73 {
  74         int ioprio, ioclass;
  75
  76         ioprio = 7; /* priority is ignored with idle class */
  77         ioclass = IOPRIO_CLASS_IDLE << IOPRIO_CLASS_SHIFT;
  78
  79         return ioprio_set (IOPRIO_WHO_PROCESS, 0, ioprio | ioclass);
  80 }
  81
  82 int set_io_priority_best_effort (int ioprio)
  83 {
  84         int ioclass;
  85
  86         ioclass = IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT;
  87
  88         return ioprio_set (IOPRIO_WHO_PROCESS, 0, ioprio | ioclass);
  89 }