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