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dd: avoid 0-filling buf at read_and_discard - #11583

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sylvestre merged 1 commit into
uutils:mainfrom
oech3:dd-bufreader
Apr 3, 2026
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dd: avoid 0-filling buf at read_and_discard#11583
sylvestre merged 1 commit into
uutils:mainfrom
oech3:dd-bufreader

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@oech3

@oech3 oech3 commented Apr 1, 2026 •
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$ truncate -s 64GB huge
$ cat huge |target/release/dd-avoid of=/dev/null bs=128M skip=64GB
0+0 records in
0+0 records out
0 bytes copied, 0.0173446 s, 0.0 B/s
$ cat huge |target/release/dd of=/dev/null bs=128M skip=64GB
0+0 records in
0+0 records out
0 bytes copied, 0.0178161 s, 0.0 B/s

@oech3
oech3 force-pushed the dd-bufreader branch 2 times, most recently from 732f02d to 8f671c7 Compare April 1, 2026 17:45
@github-actions

github-actions Bot commented Apr 1, 2026

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GNU testsuite comparison:

Skip an intermittent issue tests/date/resolution (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/date/date-locale-hour (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/tty/tty-eof (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/unexpand/bounded-memory is now being skipped but was previously passing.

@codspeed-hq

codspeed-hq Bot commented Apr 1, 2026 •
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Merging this PR will not alter performance

✅ 303 untouched benchmarks
⏩ 46 skipped benchmarks1

Comparing oech3:dd-bufreader (4c21774) with main (1e81775)

Open in CodSpeed

Footnotes

  1. 46 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

@oech3
oech3 marked this pull request as ready for review April 1, 2026 18:22
@sylvestre
sylvestre merged commit dfc08b2 into uutils:main Apr 3, 2026
165 checks passed
@oech3
oech3 deleted the dd-bufreader branch April 3, 2026 07:18
@oech3

oech3 commented Apr 6, 2026 •
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I have no idea why do I see serious perf drop with fn fill_consecutive() by avoiding 0-filling.

kevinburkesegment pushed a commit to kevinburkesegment/coreutils that referenced this pull request Apr 6, 2026
@oech3 @kevinburkesegment
dd: avoid 0-filling buf at read_and_discard (uutils#11583)
89a2dda
@moonfruit moonfruit mentioned this pull request Apr 7, 2026
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2 participants

@oech3 @sylvestre