Summary: | Handbook, section 2.3.1.1: dd(1) command uses "bs=1M" (slow), should be "bs=4k" (/much/ faster) | ||
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Product: | Documentation | Reporter: | Walter von Entferndt <walter.von.entferndt> |
Component: | Books & Articles | Assignee: | Gordon Bergling <gbe> |
Status: | Closed Not A Bug | ||
Severity: | Affects Many People | CC: | andrew, gbe, jamie |
Priority: | --- | ||
Version: | Latest | ||
Hardware: | Any | ||
OS: | Any |
Description
Walter von Entferndt
2020-06-10 07:22:01 UTC
My experience and benchmarks differ - from a freebsd stable/11 system to a random USB2 thumb drive, I get a slowdown on the order of 8x from using 4k rather than 64k block size. Block sizes of 64k, 128k, 256k, 1m give me indistinguishable speeds (note, there is basically no reason to ever use a blocksize greater than MAXPHYS when writing to a raw device, and that is 128k in standard builds). All block sizes below 64k are slower for me. status=progress is not needed on freebsd since you can always just use control-T. After internal discussions the blocksize of 1M should be the better option for most systems, because there's a lot more system calls for example. |