* Re: Do I need strong mathematical bases to work in the memory subsystem?
2019-10-03 3:42 ` Ruben Safir
@ 2019-10-03 7:00 ` Greg KH
2019-10-03 10:55 ` Ruben Safir
2019-10-06 1:49 ` Grant Taylor
2019-10-16 15:18 ` Cindy Sue Causey
2 siblings, 1 reply; 11+ messages in thread
From: Greg KH @ 2019-10-03 7:00 UTC (permalink / raw)
To: Ruben Safir; +Cc: kernelnewbies
On Wed, Oct 02, 2019 at 11:42:04PM -0400, Ruben Safir wrote:
> On 10/2/19 11:35 PM, Valdis Klētnieks wrote:
> >> If you hope to do anything that is not elementry, you need serious math
> >> for the algorithms, not to mention to complete the jobs being done.
> >>
> >> Knowing math is the real key to unlocking to potential of the power of
> >> computational mathmatics.
> >
> > If you're doing that sort of mathematics *inside the kernel*, there's probably something
> > wrong with your overall design.
> >
>
> Maybe, but I don't think so. And the hardware is getting more exotic.
"more complex" does not mean "needs more math. Look at the new USB4
spec, and the patches posted to start adding support for that to the
kernel. No "math" in there at all other than very simple stuff.
And no one can say that USB for is not "serious", so I agree with
Vladis, a deep mathmatical background is not needed for almost all of
the kernel. It's just simple C code, nothing to be afraid of.
greg k-h
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* Re: Do I need strong mathematical bases to work in the memory subsystem?
2019-10-03 7:00 ` Greg KH
@ 2019-10-03 10:55 ` Ruben Safir
2019-10-03 16:51 ` Valdis Klētnieks
0 siblings, 1 reply; 11+ messages in thread
From: Ruben Safir @ 2019-10-03 10:55 UTC (permalink / raw)
To: kernelnewbies
On 10/3/19 3:00 AM, Greg KH wrote:
> USB4
> spec, and the patches posted to start adding support for that to the
> kernel. No "math" in there at all other than very simple stuff.
>
> And no one can say that USB for is not "serious", so I agree with
> Vladis, a deep mathmatical background is not needed for almost all of
> the kernel. It's just simple C code, nothing to be afraid of.
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. You can not calculate simple interest efficiently without
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
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.
--
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that Brooklyn, like Atlantis, reaches mythological
proportions in the mind of the world - RI Safir 1998
http://www.mrbrklyn.com
DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002
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* Re: Do I need strong mathematical bases to work in the memory subsystem?
2019-10-03 10:55 ` Ruben Safir
@ 2019-10-03 16:51 ` Valdis Klētnieks
2019-10-03 17:21 ` Sahil Gupta
0 siblings, 1 reply; 11+ messages in thread
From: Valdis Klētnieks @ 2019-10-03 16:51 UTC (permalink / raw)
To: Ruben Safir; +Cc: kernelnewbies
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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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^ permalink raw reply [flat|nested] 11+ messages in thread* Re: Do I need strong mathematical bases to work in the memory subsystem?
2019-10-03 16:51 ` Valdis Klētnieks
@ 2019-10-03 17:21 ` Sahil Gupta
0 siblings, 0 replies; 11+ messages in thread
From: Sahil Gupta @ 2019-10-03 17:21 UTC (permalink / raw)
To: Valdis Klētnieks; +Cc: Ruben Safir, kernelnewbies
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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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01:20:58 PM
On Thu, Oct 3, 2019 at 12:56 PM Valdis Klētnieks <valdis.kletnieks@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?
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies@kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
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* Re: Do I need strong mathematical bases to work in the memory subsystem?
2019-10-03 3:42 ` Ruben Safir
2019-10-03 7:00 ` Greg KH
@ 2019-10-06 1:49 ` Grant Taylor
2019-10-16 15:18 ` Cindy Sue Causey
2 siblings, 0 replies; 11+ messages in thread
From: Grant Taylor @ 2019-10-06 1:49 UTC (permalink / raw)
To: kernelnewbies
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On 10/2/19 9:42 PM, Ruben Safir wrote:
> General plumbing is not needed, but predictive trees, and crypto
> certainly do and some hardware problems need calc, or even integration.
Those sound like hyper specific things and decidedly specif subsets of
the kernel.
I believe that there is a LOT of room for kernel development that does
not need advanced mathematics.
> The harder the job, the more math is needed.
math ≠ advanced mathematics
I concede that quite a bit of math is used in the kernel. But advanced
mathematics is a ⊂ of mathematics.
> Maybe, but I don't think so. And the hardware is getting more exotic.
IMHO the eccentricity of the hardware has no direct correlation to the
complexity of the device driver controlling said hardware.
Driving an external serial attached modem does not require advanced
mathematics. Creating a software based modem, be it kernel space and /
or user space, does require advanced mathematics. Notice how the
simpler hardware requires more math conversely the more complex hardware
does more of the work, thus needing simpler drivers.
--
Grant. . . .
unix || die
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* Re: Do I need strong mathematical bases to work in the memory subsystem?
2019-10-03 3:42 ` Ruben Safir
2019-10-03 7:00 ` Greg KH
2019-10-06 1:49 ` Grant Taylor
@ 2019-10-16 15:18 ` Cindy Sue Causey
2 siblings, 0 replies; 11+ messages in thread
From: Cindy Sue Causey @ 2019-10-16 15:18 UTC (permalink / raw)
To: Kernel Newbies
On 10/2/19, Ruben Safir <ruben@mrbrklyn.com> wrote:
> On 10/2/19 11:35 PM, Valdis Klētnieks wrote:
>> On Wed, 02 Oct 2019 21:47:42 -0400, Ruben Safir said:
>>
>> I'm willing to bet that there's very few PhD's in CS listed in
>> MAINTAINERS. And
>> those that are, are probably coincidental...
>
> I can't testify to that, but there are ton of Master Degree coders and a
> lot of mathamaticians.
Speaking from my own set of Shoes, some part of it is about being
attracted to something with discernible patterns.. predictable
patterns.. I don't know, words aren't quite pulling together this
morning, but..
Math and computers..
Maybe "logical" is the word I'm looking for.. If one has followed a
[building block] type of learning path for either Math or computers,
they're both actually... fun because they *can be* predictably
logical..
That is, if one has taken the logical path of learning either subject
via a [building block] type of education rather than trying to jump
off into the very deepest end first. *shakes head at self*
PS Linux From Scratch.. LFS.. I WISH I had found that first 20 years
ago before all others. It would have made a lot less sense (to me) in
that order, but all others after that would have made A LOT MORE sense
in its shadow. I think I learned about LFS from Kernel Newbies, from a
suggested further readings list or something, now that i think about
it, too. #ThankYou! :)
Cindy :)
--
* runs with birdseed *
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