skyler0x
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Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 5:27 pm

Hi everyone. I was wondering how much the Raspberry pi 4 would cost theoretically, if it had two of the same CPUs?

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rpdom
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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 5:37 pm

skyler0x wrote:
Sat Sep 26, 2020 5:27 pm
Hi everyone. I was wondering how much the Raspberry pi 4 would cost theoretically, if it had two of the same CPUs?
I'm not sure that's possible. That would mean removing two of the existing CPUs. If you really want that you can disable two of the four CPUs.
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Heater
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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 5:44 pm

A million dollars or so.

I guess the Pi Foundation could put two of the current Pi SoCs on a board.

It would be a massive development effort. A lot of time an money sunk. It would result in a much bigger board that is more expensive to make.

They would never sell in quantity. Because the board is two big and expensive and the performance would be poor. There are much cheaper ways to get more performance. Heck, just buy two Pi boards if that does what you want.

As a failed product idea it would have cost a million or so.
Memory in C++ is a leaky abstraction .

fruitoftheloom
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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 5:46 pm

skyler0x wrote:
Sat Sep 26, 2020 5:27 pm
Hi everyone. I was wondering how much the Raspberry pi 4 would cost theoretically, if it had two of the same CPUs?

The ARM CPU is an integral part of the SoC..
Thinking outside the box is better than burying your head in the sand...

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jahboater
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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 5:49 pm

fruitoftheloom wrote:
Sat Sep 26, 2020 5:46 pm
skyler0x wrote:
Sat Sep 26, 2020 5:27 pm
Hi everyone. I was wondering how much the Raspberry pi 4 would cost theoretically, if it had two of the same CPUs?

The ARM CPU is an integral part of the SoC..
And there are already four of them.
Four Cortex-A72 CPU cores.
Pi4 8GB running PIOS64 Lite

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kerry_s
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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 6:01 pm

jahboater wrote:
Sat Sep 26, 2020 5:49 pm
fruitoftheloom wrote:
Sat Sep 26, 2020 5:46 pm
skyler0x wrote:
Sat Sep 26, 2020 5:27 pm
Hi everyone. I was wondering how much the Raspberry pi 4 would cost theoretically, if it had two of the same CPUs?

The ARM CPU is an integral part of the SoC..
And there are already four of them.
Four Cortex-A72 CPU cores.
stack it up higher, make it thick, lets have 16 on the 8 gb ram model :lol:

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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 6:21 pm

kerry_s wrote:
Sat Sep 26, 2020 6:01 pm
jahboater wrote:
Sat Sep 26, 2020 5:49 pm
fruitoftheloom wrote:
Sat Sep 26, 2020 5:46 pm



The ARM CPU is an integral part of the SoC..
And there are already four of them.
Four Cortex-A72 CPU cores.
stack it up higher, make it thick, lets have 16 on the 8 gb ram model :lol:
Too much heat. We are already close to the thermal capacity of the board. Adding more heat would necessitate heatsinks and fans.
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kerry_s
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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 6:43 pm

jamesh wrote:
Sat Sep 26, 2020 6:21 pm
kerry_s wrote:
Sat Sep 26, 2020 6:01 pm
jahboater wrote:
Sat Sep 26, 2020 5:49 pm
And there are already four of them.
Four Cortex-A72 CPU cores.
stack it up higher, make it thick, lets have 16 on the 8 gb ram model :lol:
Too much heat. We are already close to the thermal capacity of the board. Adding more heat would necessitate heatsinks and fans.
i'm already using heatsinks & fan so i don't see that as a issue.
come on man, next meeting throw it out there, get'er done. :lol:

(i hope you know i'm only joking. times they are now, were lucky to have what we have)

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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 7:27 pm

The COVID virus doesn't like heat. Hot Pi could make a real contribution to controlling the virus. :ugeek: :lol: :idea:
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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 7:36 pm

kerry_s wrote:
Sat Sep 26, 2020 6:01 pm

stack it up higher, make it thick, lets have 16 on the 8 gb ram model :lol:
Go away and study Amdahl's Law.
Adding one more core doesn't give a whole core extra due to the interconnect between cores.
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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 7:42 pm

I suspect the OP overlooked the fact that all Pis starting with the Pi2Bv1.1 (but not including any Pi0 variant...yet) have had 4 CPU cores in the SoC.

It would be interesting to hear what the OP thinks more CPU cores, let alone a second SoC would provide that (a) the current design does not, and (b) would be beneficial to any use to which a Pi might be put. All of that said, I would not personally rule out that some future Pi might not have more than 4 CPU cores, but it is reasonable to rule out having a second, full, SoC.

(Note: I say all of this from the perspective of having assembled a dual-Opteron system nearly 20 years ago.)

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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 7:49 pm

.
There are a few Octa-Core ARM CPUs available over the last 5 years, but not used by Broadcom yet:

https://en.wikichip.org/wiki/octa-core
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kerry_s
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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 7:59 pm

DougieLawson wrote:
Sat Sep 26, 2020 7:36 pm
kerry_s wrote:
Sat Sep 26, 2020 6:01 pm

stack it up higher, make it thick, lets have 16 on the 8 gb ram model :lol:
Go away and study Amdahl's Law.
Adding one more core doesn't give a whole core extra due to the interconnect between cores.
did u miss the joke. nothing about that was serious.
come on man, drink some coffee & wake up. :lol:

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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 8:09 pm

W. H. Heydt wrote:
Sat Sep 26, 2020 7:42 pm
.... I would not personally rule out that some future Pi might not have more than 4 CPU cores ...
I suspect that actually says the opposite of what was intended.
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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 8:15 pm

drgeoff wrote:
Sat Sep 26, 2020 8:09 pm
W. H. Heydt wrote:
Sat Sep 26, 2020 7:42 pm
.... I would not personally rule out that some future Pi might not have more than 4 CPU cores ...
I suspect that actually says the opposite of what was intended.
You don't like triple negatives?

To put it simply: Perhaps a future Pi will have more than 4 CPU cores.

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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sat Sep 26, 2020 11:19 pm

How much money you can invest on getting two Compute modules to interact?
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W. H. Heydt
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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sun Sep 27, 2020 12:25 am

Imperf3kt wrote:
Sat Sep 26, 2020 11:19 pm
How much money you can invest on getting two Compute modules to interact?
Good point. I can't think of any reason why one couldn't make a carrier board that took two CMs. Not sure what interface(s) one would use between them... On the other hand, this is getting towards the territory of another poster who wants to mount CMs on PCI cards.

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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sun Sep 27, 2020 2:15 am

W. H. Heydt wrote:
Sun Sep 27, 2020 12:25 am
Imperf3kt wrote:
Sat Sep 26, 2020 11:19 pm
How much money you can invest on getting two Compute modules to interact?
Good point. I can't think of any reason why one couldn't make a carrier board that took two CMs. Not sure what interface(s) one would use between them... On the other hand, this is getting towards the territory of another poster who wants to mount CMs on PCI cards.
https://www.youtube.com/watch?v=xNndbfxMCLo

this would be a CM host board, with slots for 7 compute modules!
each CM gets its own usb-ethernet chip, and all of them are wired into an on-board ethernet switch, with an extra ethernet jack for outside access

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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sun Sep 27, 2020 3:46 am

Heater wrote:
Sat Sep 26, 2020 5:44 pm
A million dollars or so.

I guess the Pi Foundation could put two of the current Pi SoCs on a board.

It would be a massive development effort. A lot of time an money sunk. It would result in a much bigger board that is more expensive to make.

They would never sell in quantity. Because the board is two big and expensive and the performance would be poor. There are much cheaper ways to get more performance. Heck, just buy two Pi boards if that does what you want.

As a failed product idea it would have cost a million or so.
Or.. you could order a 8-core SoC from broadcom and use that, but that would still take alot of effort setting up raspbian, drivers, new VideoCore gpus to work on, and getting a deal with Broadcom. Generally it would be a mostly useless / not needed for what the raspberry pi is supposed to do. You really don't need a Octa-core CPU to use scratch. It would generally be a waste of time and effort for the Raspberry Pi Foundation
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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sun Sep 27, 2020 4:20 am

UbuntuWizard wrote:
Sun Sep 27, 2020 3:46 am
Or.. you could order a 8-core SoC from broadcom and use that, but that would still take alot of effort setting up raspbian, drivers, new VideoCore gpus to work on, and getting a deal with Broadcom. Generally it would be a mostly useless / not needed for what the raspberry pi is supposed to do. You really don't need a Octa-core CPU to use scratch. It would generally be a waste of time and effort for the Raspberry Pi Foundation
That brings to mind the joke about the patron of a specialty restaurant who orders an elephant cutlet.

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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sun Sep 27, 2020 5:12 pm

How about writing more efficient code... Use what we have, now, more efficient.

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jahboater
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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sun Sep 27, 2020 5:34 pm

Puffergas wrote:
Sun Sep 27, 2020 5:12 pm
How about writing more efficient code... Use what we have, now, more efficient.
The OP is asking for less CPU's than the Pi4 already has :)
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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sun Sep 27, 2020 5:50 pm

jahboater wrote:
Sun Sep 27, 2020 5:34 pm
Puffergas wrote:
Sun Sep 27, 2020 5:12 pm
How about writing more efficient code... Use what we have, now, more efficient.
The OP is asking for less CPU's than the Pi4 already has :)
I'll give you a solid "maybe" on that. It's not entirely clear what he means by "CPU" or that he understands that the "cores" that get talked about are CPUs. One could read the OP as meaning "two SoCs", and I think that's what several of the replies take it to be. I rather suspect that a fair number of people take SoC and CPU as synonymous...which feeds into my tendency to be picky about terminology and usage of technical terms.

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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sun Sep 27, 2020 6:03 pm

W. H. Heydt wrote:
Sun Sep 27, 2020 5:50 pm
jahboater wrote:
Sun Sep 27, 2020 5:34 pm
Puffergas wrote:
Sun Sep 27, 2020 5:12 pm
How about writing more efficient code... Use what we have, now, more efficient.
The OP is asking for less CPU's than the Pi4 already has :)
I'll give you a solid "maybe" on that. It's not entirely clear what he means by "CPU" or that he understands that the "cores" that get talked about are CPUs. One could read the OP as meaning "two SoCs", and I think that's what several of the replies take it to be. I rather suspect that a fair number of people take SoC and CPU as synonymous...which feeds into my tendency to be picky about terminology and usage of technical terms.
there is also the complication of how many cores the pi even has, its a lot higher then you think

there is 1-4 arm cores (based on model)
2 vpu cores
there are ~192 qpu cores (less on pi4, but higher clock), that run opengl shaders
there are the ISP and VCE cores (basically a black-box), that handle camera image processing and video decoding
and the pi4 also has the ddr4 and vl805 controller which have firmware to manage those parts

of those, i can see arm/vpu/qpu/isp/vce being useful to user compuation, but only arm/qpu are commonly used

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Re: Q: How much would a Raspberry pi 4 costed with two CPUs

Sun Sep 27, 2020 6:09 pm

Wait up a minute.

Our OP was asking about two CPU's.

That is "Central Processing Units". As far as I know.

The keyword here for me is "central".

Clearly there can only be one "central" thing. If there were more than one it would not be central anymore now would it.

Which is likely why we talk about "cores" now a days.
Memory in C++ is a leaky abstraction .

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