i386 version in future ?

[Michał Jędrzejczak]

Thanks everyone for answers, now I know lot of more what I wanted :)


Regards
Michał Jędrzejczak

2016-09-28 16:55 GMT+02:00 Valeri Galtsev <galtsev at kicp.uchicago.edu>:

> On Wed, September 28, 2016 3:54 am, Ralf Mardorf via freebsd-questions
> wrote:
> > On Wed, 28 Sep 2016 00:59:09 -0700, Mehmet Erol Sanliturk wrote:
> >>You are comparing different CPU brands with each other .
> >
> > It's unrealistic to compare 32 bit and 64 CPUs, produced with the same
> level of development. Could you provide some examples?
> >
> > Actually I'm comparing two CPUs from the same family. The CPU I'm using
> for my desktop computer today and the last 32 bit CPU I used for my
> desktop computer before I switched to 64 bit.
> >
> > My old 32 bit was an Athlon single core 800, 850 or 900 MHz, I don't
> remember exactly, Socket A, so the consumption was between >= 42.6 W and
> <= 49.7. My current, newer 64 bit dual core is an Athlon BE-2350, 2100
> MHz, Socket AM2, 45 W.
> >
> >>Assume that two CPUs are produced with the  SAME technology .
> >>A 64 bit CPU will contain more circuits than a 32 bit CPU , means more
> power it will use because amount of power will be proportional to number
> of circuit components and length of connection lines .
> >
> > But they are not produced with the same technology, the 32 bit
> > Athlon I mentioned requires 1.70 V or 1.75 V, the 64 bit Athlon I
> mentioned 1.25 V, they are anyway from the same family, they were just not
> produced with the same level of development.
>
> This is true: the power goes mostly into charging and discharging
> capacitances associated with FET gates (ans stray capacitances). Energy
> associated with charge is (C*(U)^2)/2. If we use half of voltage this
> energy drops 4 times! (hence consumed power drops 4 times). This is why
> the highest frequency part (core) works at lower voltage than the rest of
> CPU. Now, there is also capacitance C in that formulae, which roughly
> speaking is proportional to gate area (it is more sophisticated, yet...).
> So, the technology goes to twice as small nanometers (which are linear
> dimensions of elements), then the capacitance diminishes 4 times. That is
> why it only makes sense to compare "the same technology". Next, the CPUs
> are more sophisticated than just a width of arithmetic unit which for 64
> bit would be twice than for 32 bit if CPUs were trivial devices. Actually
> it is not quite so, thus processing some amount of 32 bit CPU work on 64
> bin CPU will (considering the rest equal) not require to spend twice the
> energy as compared to 32 bit CPU. You will spend more energy, this is
> correct, but not two times more. (Very crude analogy here is: powering off
> unused CPU cores; somewhat parallel utilization of components of 64 bit
> CPU when processing 32 bit stuff probably is less crude way of saying it).
>
> Anyway, thanks, everybody for refreshing and very insightful discussion!
>
> Valeri
>
> >
> > The slower CPU, slower RAM, different hardware, IDE etc., made the old
> computer almost half as fast, so it needs to run almost double the time,
> to reach the same processing power.
> >
> > https://en.wikipedia.org/wiki/List_of_CPU_power_dissipation_
> figures#AMD_Athlon_64_X2_.2F_Athlon_X2
> http://www.anandtech.com/show/557/3
> >
> > Regards,
> > Ralf
> > _______________________________________________
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>
>
> ++++++++++++++++++++++++++++++++++++++++
> Valeri Galtsev
> Sr System Administrator
> Department of Astronomy and Astrophysics
> Kavli Institute for Cosmological Physics
> University of Chicago
> Phone: 773-702-4247
> ++++++++++++++++++++++++++++++++++++++++
>
>
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