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Diffstat (limited to 'include/uapi/linux/ioprio.h')
-rw-r--r-- | include/uapi/linux/ioprio.h | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/include/uapi/linux/ioprio.h b/include/uapi/linux/ioprio.h new file mode 100644 index 000000000..bee2bdb0e --- /dev/null +++ b/include/uapi/linux/ioprio.h @@ -0,0 +1,127 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef _UAPI_LINUX_IOPRIO_H +#define _UAPI_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 /* _UAPI_LINUX_IOPRIO_H */ |