dd: improve malloc perf

[oech3]

No description provided.

[codspeed-hq]

Merging this PR will improve performance by ×7.8

⚡ 8 improved benchmarks
✅ 301 untouched benchmarks
⏩ 46 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	dd_copy_partial	320 µs	269.8 µs	+18.59%
⚡	Simulation	dd_copy_4k_blocks	1,078.7 µs	803.7 µs	+34.22%
⚡	Simulation	dd_copy_with_seek	2 ms	1.5 ms	+36.8%
⚡	Simulation	dd_copy_with_skip	2 ms	1.4 ms	+36.5%
⚡	Simulation	dd_copy_64k_blocks	366.2 µs	255.2 µs	+43.52%
⚡	Simulation	dd_copy_default	13.7 ms	10.9 ms	+25.93%
⚡	Simulation	dd_copy_8k_blocks	776.8 µs	588.3 µs	+32.03%
⚡	Simulation	dd_copy_1m_blocks	1,228.3 µs	157.2 µs	×7.8

---

_{Comparing oech3:dd-malloc-2 (736cf57) with main (56210f1)}

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. ↩

[ghost]

GNU testsuite comparison:

GNU test failed: tests/dd/misc. tests/dd/misc is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/dd/stats. tests/dd/stats is passing on 'main'. Maybe you have to rebase?
Skip an intermittent issue tests/tail/symlink (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)
Note: The gnu test tests/printf/printf-surprise is now being skipped but was previously passing.

[ghost]

GNU testsuite comparison:

GNU test failed: tests/cat/cat-buf. tests/cat/cat-buf is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/dd/misc. tests/dd/misc is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/dd/reblock. tests/dd/reblock is passing on 'main'. Maybe you have to rebase?
Skip an intermittent issue tests/tail/inotify-dir-recreate (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/tty/tty-eof (fails in this run but passes in the 'main' branch)

[ghost]

GNU testsuite comparison:

GNU test failed: tests/cat/cat-buf. tests/cat/cat-buf is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/dd/misc. tests/dd/misc is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/dd/reblock. tests/dd/reblock is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/dd/stats. tests/dd/stats is passing on 'main'. Maybe you have to rebase?
Skip an intermittent issue tests/pr/bounded-memory (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/tty/tty-eof (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)

[ghost]

GNU testsuite comparison:

GNU test failed: tests/cat/cat-buf. tests/cat/cat-buf is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/dd/misc. tests/dd/misc is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/dd/reblock. tests/dd/reblock is passing on 'main'. Maybe you have to rebase?
Skip an intermittent issue tests/pr/bounded-memory (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/tail/tail-n0f (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/tty/tty-eof (fails in this run but passes in the 'main' branch)

[ghost]

GNU testsuite comparison:

GNU test failed: tests/cat/cat-buf. tests/cat/cat-buf is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/dd/misc. tests/dd/misc is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/dd/reblock. tests/dd/reblock is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/dd/stats. tests/dd/stats is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/tail/retry. tests/tail/retry is passing on 'main'. Maybe you have to rebase?
Skip an intermittent issue tests/cut/bounded-memory (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/pr/bounded-memory (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/tty/tty-eof (fails in this run but passes in the 'main' branch)

[oech3]

@mattsu2020 Would you take this over?