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In include/usapi/linux/ioprio.h, change the ioprio class enum comment to remove the outdated reference to CFQ and mention BFQ and mq-deadline instead. Also document the high priority NCQ command use for RT class IOs directed at ATA drives that support NCQ priority. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Link: https://lore.kernel.org/r/20210811033702.368488-3-damien.lemoal@wdc.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
49 lines
1.3 KiB
C
49 lines
1.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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#ifndef _UAPI_LINUX_IOPRIO_H
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#define _UAPI_LINUX_IOPRIO_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_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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/*
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* These are the io priority groups as implemented by the BFQ and mq-deadline
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* schedulers. RT is the realtime class, it always gets premium service. For
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* ATA disks supporting NCQ IO priority, RT class IOs will be processed using
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* high priority NCQ commands. BE is the best-effort scheduling class, the
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* default for any process. IDLE is the idle scheduling class, it is only
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* 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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#define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
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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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/*
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* Fallback BE priority
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*/
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#define IOPRIO_NORM (4)
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#endif /* _UAPI_LINUX_IOPRIO_H */
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