Viewing file:  ioprio.h (4.08 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
/* 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 */
|