Greg Kroah-Hartman
598cf27219
Link: https://lore.kernel.org/r/20260217200002.683975158@linuxfoundation.org Tested-by: Florian Fainelli <florian.fainelli@broadcom.com> Tested-by: Takeshi Ogasawara <takeshi.ogasawara@futuring-girl.com> Tested-by: Peter Schneider <pschneider1968@googlemail.com> Tested-by: Jon Hunter <jonathanh@nvidia.com> Tested-by: Salvatore Bonaccorso <carnil@debian.org> Tested-by: Brett A C Sheffield <bacs@librecast.net> Tested-by: Mark Brown <broonie@kernel.org> Tested-by: Luna Jernberg <droidbittin@gmail.com> Tested-by: Ronald Warsow <rwarsow@gmx.de> Tested-by: Justin M. Forbes <jforbes@fedoraproject.org> Tested-by: Ron Economos <re@w6rz.net> Tested-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
55 lines
1.6 KiB
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55 lines
1.6 KiB
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========
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dm-delay
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========
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Device-Mapper's "delay" target delays reads and/or writes
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and/or flushes and optionally maps them to different devices.
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Arguments::
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<device> <offset> <delay> [<write_device> <write_offset> <write_delay>
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[<flush_device> <flush_offset> <flush_delay>]]
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Table line has to either have 3, 6 or 9 arguments:
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3: apply offset and delay to read, write and flush operations on device
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6: apply offset and delay to device, also apply write_offset and write_delay
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to write and flush operations on optionally different write_device with
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optionally different sector offset
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9: same as 6 arguments plus define flush_offset and flush_delay explicitly
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on/with optionally different flush_device/flush_offset.
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Offsets are specified in sectors.
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Delays are specified in milliseconds.
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Example scripts
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===============
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::
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#!/bin/sh
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#
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# Create mapped device named "delayed" delaying read, write and flush operations for 500ms.
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#
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dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 0 500"
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::
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#!/bin/sh
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#
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# Create mapped device delaying write and flush operations for 400ms and
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# splitting reads to device $1 but writes and flushes to different device $2
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# to different offsets of 2048 and 4096 sectors respectively.
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#
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dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 2048 0 $2 4096 400"
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::
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#!/bin/sh
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#
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# Create mapped device delaying reads for 50ms, writes for 100ms and flushes for 333ms
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# onto the same backing device at offset 0 sectors.
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#
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dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 0 50 $2 0 100 $1 0 333"
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