Re: [bug] dd piped input truncates ~1% of values to %4096 on multi-core systems

John Thomson lists at johnthomson.fastmail.com.au
Mon Nov 30 09:00:22 UTC 2020


On Mon, 30 Nov 2020, at 08:39, Walter Harms wrote:
> did you play with the buffering (man stdbuf) ?
> I suspect the kernel has a more aggressive buffering these days.
> In one project i had to add fflush() to make sure that i really get all
> data. I never found a good explanation.

I will look into it. Thank you.

I have now found the fullblock iflag [1], which consistently gives me the expected result.
Guessing the issue I was seeing relates to my bs being greater than PIPE_BUF?

[1]: https://git.busybox.net/busybox/commit/coreutils/dd.c?id=77a6678c427db5ea15d6d0005a579f441277df06

Cheers,
-- 
  John Thomson


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