Do I need strong mathematical bases to work in the memory subsystem?

[Sahil Gupta]

Guys,
It would be more helpful if everybody states their own experience with
respect to kernel development.
It sounds more like a fight now.
:)
The question was originally asked by "CRISTIAN ANDRES".
He is nowhere in the conversation now.
Let's see if he has some specific query with respect to the ram memory
subsystem.

Cheers
Sahil Gupta


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On Thu, Oct 3, 2019 at 12:56 PM Valdis Klētnieks <valdis.kletnieks at vt.edu>
wrote:

> On Thu, 03 Oct 2019 06:55:50 -0400, Ruben Safir said:
>
> > I wouldn't call that C code basic.  Regardless, showing an example of a
> > driver that doesn't need math, and it might if you understood the high
> > level math, and your not aware of it, but predictive branching would
> > need it.
>
> See the kernel code that maintains statistical data on likely()/unlikely()
> under CONFIG_PROFILE_ANNOTATED_BRANCHES. Seems like "this likely() actually
> only triggers 3% of the time" isn't exactly higher math.
>
> There may be some magic going on in the chip hardware - but that's in the
> *hardware* and inaccessible to the programmer.  I'll also point out that
> speculative execution has *other* problems.....
>
> > You can not calculate simple interest efficiently without calculus.
>
> Simple interest is *easy*.  Amount * percent.  Done.  It's compound
> interest
> that only sort of needs calculus (and there only to understand the limiting
> case) - and even there I doubt any banks actually use calculus, just apply
> the
> iterative approach.
>
> //  yearly interest compounded monthly
> for (i=0;i<num_months;i++) { balance += (balance * percent) /12;}
>
> I'd like to see you do it more efficiently using calculus. Especially if
> you
> have to take into account rounding to the nearest penny 36 times for a 3
> year loan.  That stuff is why COBOL is still around. :)
>
> > calculus.  This repeadely ends up being an issue of "if I don't know it,
> > I don't need it", which is wrong.  More math helps you every time.  Math
>
> Somehow I doubt that the Taniyama-Shimura-Weil conjecture is ever
> going to have any relevance inside the kernel.
>
> > is advanced logic.  I can't tell you how many times I see folks brute
> > force their way to solutions that they should be using integration.
>
> Can you show an example of where the kernel needs to be using integration?
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