#ifndef IOPRIO_H #define IOPRIO_H /* This is minimal version of Linux' linux/ioprio.h header file, which * is licensed GPL2 */ #include <sys/syscall.h> #include <unistd.h> /* * Gives us 8 prio classes with 13-bits of data for each class */ #define IOPRIO_BITS (16) #define IOPRIO_CLASS_SHIFT (13) #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) #define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT) #define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK) #define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data) #define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE) /* * These are the io priority groups as implemented by CFQ. RT is the realtime * class, it always gets premium service. BE is the best-effort scheduling * class, the default for any process. IDLE is the idle scheduling class, it * is only served when no one else is using the disk. */ enum { IOPRIO_CLASS_NONE, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE, }; /* * 8 best effort priority levels are supported */ #define IOPRIO_BE_NR (8) enum { IOPRIO_WHO_PROCESS = 1, IOPRIO_WHO_PGRP, IOPRIO_WHO_USER, }; static inline int ioprio_set(int which, int who, int ioprio) { return syscall(__NR_ioprio_set, which, who, ioprio); } static inline int ioprio_get(int which, int who) { return syscall(__NR_ioprio_get, which, who); } #endif