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ioprio.h
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/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ #ifndef _LINUX_IOPRIO_H #define _LINUX_IOPRIO_H #include <linux/stddef.h> #include <linux/types.h> /* * Gives us 8 prio classes with 13-bits of data for each class */ #define IOPRIO_CLASS_SHIFT 13 #define IOPRIO_NR_CLASSES 8 #define IOPRIO_CLASS_MASK (IOPRIO_NR_CLASSES - 1) #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) #define IOPRIO_PRIO_CLASS(ioprio) \ (((ioprio) >> IOPRIO_CLASS_SHIFT) & IOPRIO_CLASS_MASK) #define IOPRIO_PRIO_DATA(ioprio) ((ioprio) & IOPRIO_PRIO_MASK) /* * These are the io priority classes as implemented by the BFQ and mq-deadline * schedulers. RT is the realtime class, it always gets premium service. For * ATA disks supporting NCQ IO priority, RT class IOs will be processed using * high priority NCQ commands. 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 = 0, IOPRIO_CLASS_RT = 1, IOPRIO_CLASS_BE = 2, IOPRIO_CLASS_IDLE = 3, /* Special class to indicate an invalid ioprio value */ IOPRIO_CLASS_INVALID = 7, }; /* * The RT and BE priority classes both support up to 8 priority levels that * can be specified using the lower 3-bits of the priority data. */ #define IOPRIO_LEVEL_NR_BITS 3 #define IOPRIO_NR_LEVELS (1 << IOPRIO_LEVEL_NR_BITS) #define IOPRIO_LEVEL_MASK (IOPRIO_NR_LEVELS - 1) #define IOPRIO_PRIO_LEVEL(ioprio) ((ioprio) & IOPRIO_LEVEL_MASK) #define IOPRIO_BE_NR IOPRIO_NR_LEVELS /* * Possible values for the "which" argument of the ioprio_get() and * ioprio_set() system calls (see "man ioprio_set"). */ enum { IOPRIO_WHO_PROCESS = 1, IOPRIO_WHO_PGRP, IOPRIO_WHO_USER, }; /* * Fallback BE class priority level. */ #define IOPRIO_NORM 4 #define IOPRIO_BE_NORM IOPRIO_NORM /* * The 10 bits between the priority class and the priority level are used to * optionally define I/O hints for any combination of I/O priority class and * level. Depending on the kernel configuration, I/O scheduler being used and * the target I/O device being used, hints can influence how I/Os are processed * without affecting the I/O scheduling ordering defined by the I/O priority * class and level. */ #define IOPRIO_HINT_SHIFT IOPRIO_LEVEL_NR_BITS #define IOPRIO_HINT_NR_BITS 10 #define IOPRIO_NR_HINTS (1 << IOPRIO_HINT_NR_BITS) #define IOPRIO_HINT_MASK (IOPRIO_NR_HINTS - 1) #define IOPRIO_PRIO_HINT(ioprio) \ (((ioprio) >> IOPRIO_HINT_SHIFT) & IOPRIO_HINT_MASK) /* * I/O hints. */ enum { /* No hint */ IOPRIO_HINT_NONE = 0, /* * Device command duration limits: indicate to the device a desired * duration limit for the commands that will be used to process an I/O. * These will currently only be effective for SCSI and ATA devices that * support the command duration limits feature. If this feature is * enabled, then the commands issued to the device to process an I/O with * one of these hints set will have the duration limit index (dld field) * set to the value of the hint. */ IOPRIO_HINT_DEV_DURATION_LIMIT_1 = 1, IOPRIO_HINT_DEV_DURATION_LIMIT_2 = 2, IOPRIO_HINT_DEV_DURATION_LIMIT_3 = 3, IOPRIO_HINT_DEV_DURATION_LIMIT_4 = 4, IOPRIO_HINT_DEV_DURATION_LIMIT_5 = 5, IOPRIO_HINT_DEV_DURATION_LIMIT_6 = 6, IOPRIO_HINT_DEV_DURATION_LIMIT_7 = 7, }; #define IOPRIO_BAD_VALUE(val, max) ((val) < 0 || (val) >= (max)) /* * Return an I/O priority value based on a class, a level and a hint. */ static __always_inline __u16 ioprio_value(int prioclass, int priolevel, int priohint) { if (IOPRIO_BAD_VALUE(prioclass, IOPRIO_NR_CLASSES) || IOPRIO_BAD_VALUE(priolevel, IOPRIO_NR_LEVELS) || IOPRIO_BAD_VALUE(priohint, IOPRIO_NR_HINTS)) return IOPRIO_CLASS_INVALID << IOPRIO_CLASS_SHIFT; return (prioclass << IOPRIO_CLASS_SHIFT) | (priohint << IOPRIO_HINT_SHIFT) | priolevel; } #define IOPRIO_PRIO_VALUE(prioclass, priolevel) \ ioprio_value(prioclass, priolevel, IOPRIO_HINT_NONE) #define IOPRIO_PRIO_VALUE_HINT(prioclass, priolevel, priohint) \ ioprio_value(prioclass, priolevel, priohint) #endif /* _LINUX_IOPRIO_H */