58 lines
1.8 KiB
Markdown
58 lines
1.8 KiB
Markdown
# Test Case: LZ4 Sequential Read Correctness
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**Test ID**: TC086-lz4-sequential-read
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**G5 fixture contract**: Use [G5-MANUAL-SETUP.md](G5-MANUAL-SETUP.md).
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Its generated paths, source comparisons, structured corruption offsets, and
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cleanup rules supersede placeholder examples in this file.
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**Category**: Compression
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**Priority**: High
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## Objective
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Verify complete sequential reads of an LZ4-compressed file with two request
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sizes against the original source bytes. Record timings only; repo22 exposes no
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filesystem-specific DTrace provider and this test has no fixed throughput
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threshold.
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## Fixture
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```sh
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work=$(mktemp -d /tmp/repo22-tc086.XXXXXX)
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tests/prepare_error_fixtures.sh "$work/fixtures"
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dump.erofs -s "$work/fixtures/valid-lz4.erofs"
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dump.erofs --path=/compressed.bin -e "$work/fixtures/valid-lz4.erofs"
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```
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The dump must identify `/compressed.bin` as compressed LZ4 data with real
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physical extents.
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## FreeBSD Procedure
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```sh
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mkdir "$work/mnt"
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unit=$(mdconfig -a -t vnode -f "$work/fixtures/valid-lz4.erofs")
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mount -t erofs -o ro "/dev/$unit" "$work/mnt"
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expected=$(sha256 -q "$work/fixtures/source/compressed.bin")
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actual=$(sha256 -q "$work/mnt/compressed.bin")
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test "$actual" = "$expected"
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/usr/bin/time -p dd if="$work/mnt/compressed.bin" \
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of="$work/read-4k.bin" bs=4096 2>"$work/time-4k.txt"
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cmp "$work/fixtures/source/compressed.bin" "$work/read-4k.bin"
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/usr/bin/time -p dd if="$work/mnt/compressed.bin" \
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of="$work/read-1m.bin" bs=1048576 2>"$work/time-1m.txt"
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cmp "$work/fixtures/source/compressed.bin" "$work/read-1m.bin"
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cat "$work/time-4k.txt" "$work/time-1m.txt"
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umount "$work/mnt"
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mdconfig -d -u "${unit#md}"
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```
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## Expected Results
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Both complete outputs compare byte-for-byte with the source and both hashes
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match. Timing values are recorded with guest CPU, VM, and storage context; one
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buffer size is not required to outperform the other.
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