threeeye
bc1d038eac
Squashed backup commit (no shallow-clone history issues) of xiaomi-mt6833-dev/kernel_xiaomi_mt6833 (lineage-23.2 branch, upstream commit 9eece662e) plus all fixes applied to get everpal_defconfig building clean against a modern (GCC 15.2.0) toolchain -- see the previous commit message on the lineage-23.2 branch (also in this repo history is not available here since this is a squashed snapshot; full incremental history lives in the local DL380 checkout and the upstream GitHub remote). Upstream: https://github.com/xiaomi-mt6833-dev/kernel_xiaomi_mt6833 (lineage-23.2)
40 lines
1.2 KiB
Plaintext
40 lines
1.2 KiB
Plaintext
dm-queue-length
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===============
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dm-queue-length is a path selector module for device-mapper targets,
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which selects a path with the least number of in-flight I/Os.
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The path selector name is 'queue-length'.
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Table parameters for each path: [<repeat_count>]
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<repeat_count>: The number of I/Os to dispatch using the selected
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path before switching to the next path.
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If not given, internal default is used. To check
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the default value, see the activated table.
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Status for each path: <status> <fail-count> <in-flight>
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<status>: 'A' if the path is active, 'F' if the path is failed.
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<fail-count>: The number of path failures.
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<in-flight>: The number of in-flight I/Os on the path.
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Algorithm
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=========
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dm-queue-length increments/decrements 'in-flight' when an I/O is
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dispatched/completed respectively.
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dm-queue-length selects a path with the minimum 'in-flight'.
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Examples
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========
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In case that 2 paths (sda and sdb) are used with repeat_count == 128.
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# echo "0 10 multipath 0 0 1 1 queue-length 0 2 1 8:0 128 8:16 128" \
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dmsetup create test
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#
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# dmsetup table
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test: 0 10 multipath 0 0 1 1 queue-length 0 2 1 8:0 128 8:16 128
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#
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# dmsetup status
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test: 0 10 multipath 2 0 0 0 1 1 E 0 2 1 8:0 A 0 0 8:16 A 0 0
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