ioprio.h (4175B)
- /* 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 */