[TUHS] Re: Clever code

[Warner Losh <imp@bsdimp.com>]

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On Mon, Dec 12, 2022, 8:32 PM Rudi Blom <rudi.j.blom@gmail.com> wrote:

>
> I vaguely remember having read here about 'clever code' which took into
> account the time a magnetic drum needed to rotate in order to optimise
> access.
>

Yes. Many ways this was done. Biggest ones were interleaving and striding.
Interleaving allowed one a little processing time for each sector while the
disk fpu. So the next logical sector isn't the next physical... and the
sectors are numbered in adjacent tracks to take into account rotation and
seek times.... there is a lot of research here...

Warner

Similarly I can imagine that with resource restraints you sometimes need to
> be clever in order to get your program to fit. Of course, any such
> cleverness needs extra documentation.
>
> I only ever programmed in user space but even then without lots of comment
> in my code I may already start wondering what I did after only a few months
> past.
>
> Cheers,
> uncle rubl
> --
> The more I learn the better I understand I know nothing.
>
>

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