6by9
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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 12:20 am

Heater wrote:6by9,
The ONLY thing that architecture decision really affects is the boot process...
Technically I believe you are right.

However the happenstance that Eben found work at Broadcom and could co-opt the Video Core for his Raspberry Pi vision set the "genetics" of what we have now.

Had Eben found work elsewhere the Pi may never have happened, or at least been a very different machine.

Now, is it really so that an ARM core with 2, 4, 8, whatever, gigabytes of RAM can be used with the current Video Core? The way I have read things is "no".
Had Eben been working elsewhere then it is highly unlikely that Pi would be using the Broadcom chip - they wouldn't have entertained the predicted numbers.

There were phones shipped which used a Broadcom chip with full VC4 IP and had more than 1GB of ram (1.5GB iirc). They had funny memory management arrangements which were a pain in the neck to handle any shared Gpu resources. Not possible on the 2835/6/7, but not precluded totally by VC4.
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Gavinmc42
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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 12:26 am

It was a useful test.
If you want to compile large stuff on a Pi you need to know it's limits.
Just watch the memory get gobbled on a Pi3 when you start using Chromium and have lots of tabs open.

Is the RPF going to stick forever with the BCM2837?

I have vision of guardians at the gate of Pi House with sticks beating off chip manufacturers.
Who will get their chip in the Pi 4?

What sort of numbers would they be interested in selling, 10million? done already, 100milllion chips, 1Billion?
Those are reasonably large numbers.

There is a still a few years of life left in the BCM2837, but what if Broadcom change processes?
Will Broadcom still want to make an old chip?
RPF have made the target price clear, who can meet that price?
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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 12:35 am

Heater wrote:Don't forget to do a "make clean" first. Or perhaps delete everything and start from scratch. Jusr to be sure the same work gets done again.
./configure takes 17 min with -j1, i'm trying make now.
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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 1:20 am

wildfire wrote:What extremes? My first computer had 4K of ram
Raspbian is based on GNU software that is currently developed on machines with more than 1GB of RAM. While programmers naturally optimize software for the capabilities of computers in common use, the GNU project has a history of preferring to use more memory in order to simplify algorithms.
Richard Stallman wrote:In addition, we rejected the Unix focus on small memory size
While he is talking about 16-bit versus 32-bit architectures in that early essay, the guiding principle seems to have carried over to the question of 32-bit versus 64-bit architectures. In particular, it comes as no surprise that a full GNU/Linux system is currently happier with more than 1GB RAM. Other operating systems, for example RiscOS and probably Plan 9, may not need as much RAM to run.

It would have been interesting if, instead of putting all that effort into Raspbian, the foundation worked to make RiscOS run on SMP hardware.

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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 2:46 am

DougieLawson wrote:
ric96 wrote:
DougieLawson wrote:... you're not going to make a difference, so why bother.
never wanted to, just showing the kinds of extremes one has to go before requiring to have more than a gig of ram.
Stop it. The code folks write these days will expand to fill the space available because they never learned the lessons from the old fogies with beard and sandals who've been beating computers into submission for nearly forty years.
Well...in reality, we were filling all available memory 40 years ago, too. There was just a lot less of it to fill up (and no virtual memory to fake it being bigger). Since the S/360 was mentioned already, note that the maximum possible memory for any S/360 was 16MB...and at one time that cost $75K per megabyte.

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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 3:40 am

So now we know Dougie's real age. Next he will tell us how he used his teeth to rip the bark off reeds to make papyrus tape. :D

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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 3:45 am

My biggest project ran to 0.56 GB. 2 GB would let me start the program using cinnamon instead of LXDE. I could use KDE to start the program if I had 16 terabytes.

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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 9:35 am

peterlite wrote:So now we know Dougie's real age. Next he will tell us how he used his teeth to rip the bark off reeds to make papyrus tape. :D
My age is in my forum profile. Why shouldn't folks know that I was born in April 1963 about 15 minutes before my twin brother?
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dasmanul
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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 10:29 am

Out of curiosity: Have you tried the ./configure with swap disabled? I'd be interested to see how long that takes.

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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 1:06 pm

@peterlite,
So now we know Dougie's real age. Next he will tell us how he used his teeth to rip the bark off reeds to make papyrus tape.
Nah, that would be me. Dougie, the young whippersnapper that he is, is not old enough to have cut his teeth by punching paper tape :)

@dasmanul,

If the Qt build does not need more memory than is physically available then turning off swap should not make any difference. (Assuming nothing else is eating your RAM at the time).

If it does need more memory then turning off swap will cause it to fail.

When I built Qt5 I had to put up quite a large swap file. I put it on a NFS share on my PC so as to save SD wear and get a bit more speed.

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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 1:15 pm

@Heater: I can't imagine that the mere configure actually *needs* more than 1 GB of RAM. What I could imagine, however, is that it somehow grabs as much RAM as it can get - which might make sense if what it got really was RAM instead of swap space on an SD card. I'll happily admit that that is pure guessing on my part, that's why I'm curious to find out what effect it actually has.

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ric96
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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 1:20 pm

dasmanul wrote:@Heater: I can't imagine that the mere configure actually *needs* more than 1 GB of RAM. What I could imagine, however, is that it somehow grabs as much RAM as it can get - which might make sense if what it got really was RAM instead of swap space on an SD card. I'll happily admit that that is pure guessing on my part, that's why I'm curious to find out what effect it actually has.
Configure also builds qmake and that is what takes up the ram.
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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 1:54 pm

Thanks, I wasn't aware of that. I'd still be curious to know whether it actually *needs* more than 1GB of RAM - but not enough to try it out admittedly. ;)

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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 2:01 pm

dasmanul wrote:Thanks, I wasn't aware of that. I'd still be curious to know whether it actually *needs* more than 1GB of RAM - but not enough to try it out admittedly. ;)
I explicitly exported makeflag as -j4, it doesn't matter in single core builds.
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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 2:26 pm

Ah, to be so young. I was born in '44, and I cut my computing teeth on an NCR500, 400 words of ferrite core each of 12 BCD digits, 4 address instructions, ( 1st operand address, 2nd operand address, result address, next instruction address )
Roger
DougieLawson wrote:
peterlite wrote:So now we know Dougie's real age. Next he will tell us how he used his teeth to rip the bark off reeds to make papyrus tape. :D
My age is in my forum profile. Why shouldn't folks know that I was born in April 1963 about 15 minutes before my twin brother?

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Michiel O.
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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 3:48 pm

rotwang wrote:400 words of ferrite core each of 12 BCD digits
Luxury. In my day we had to do with 20 abacus beads on a snapped string, and we had to calculate M_PI to 5 million digits with only two hours of sleep per day and no food, if we were lucky! But you try and tell the young people today that... and they won't believe you.

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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 4:10 pm

Ey, when I were a lad, we had t' recite Python sketches, backwards, in klingon, 40 hours per day. Tell kids today, 'eck dozy buggers 'ill believe anything.

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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 10:30 pm

Heater wrote:@peterlite,
So now we know Dougie's real age. Next he will tell us how he used his teeth to rip the bark off reeds to make papyrus tape.
I am old enough to have used an IBM 029 card punch to create input used in production programs. I messed up a bank base rate with a badly punched card one day.
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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 10:51 pm

DougieLawson wrote:
Heater wrote:@peterlite,
So now we know Dougie's real age. Next he will tell us how he used his teeth to rip the bark off reeds to make papyrus tape.
I am old enough to have used an IBM 029 card punch to create input used in production programs. I messed up a bank base rate with a badly punched card one day.
Ah... You were using *modern* gear. I cut my teeth on 024 and 026 keypunches, with an 011 for occasional, near emergency, use. (Quick...what's the difference between an 024 and an 026?)

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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Fri Dec 30, 2016 11:45 pm

Any of you guys remember what the "HERE IS" key was for on 1970's vintage teletypes?

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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Sat Dec 31, 2016 1:01 am

Heater wrote:Any of you guys remember what the "HERE IS" key was for on 1970's vintage teletypes?
From https://en.wikipedia.org/wiki/Teleprint ... _is.22_key

BeginQuote. Some teleprinters had a "Here is" key, which transmitted a fixed sequence 20 or 22 characters, programmable by breaking tabs off a drum. This sequence could also be transmitted automatically upon receipt of an ENQ (control E) signal, if enabled. This was commonly used to identify a station; the operator could press the key to send the station identifier to the other end, or the remote station could trigger its transmission by sending the ENQ character, essentially asking "who are you?" EndQuote

AFAIK if you had the printout of a message with the other end's identifier at the beginning and end, it would stand up in UK courts as proof of the communication.

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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Sat Dec 31, 2016 8:56 am

That's right.

We had a teletype in technical college back in '74. Used for our programming classes. It had a "HERE IS" key. Nobody knew what it was for. It did nothing when you pressed it.

The "HERE IS" key seemed like some mysteriously deep philosophical thing. Like "I think therefor I am" or "To be or not to be". I became totally mesmerized, fascinated by it.

For years later when I arrived at interesting places or happy moments in life I would find myself thinking "HERE IS". And a vision of that key would come to mind.

It's only a year of so ago I thought of "HERE IS" again and, of course, found it on wikipedia. What a disappointment. So mundane.

It occurs to me now that I have to build myself a "HERE IS" key. When pressed it could emit GPS coordinates or some such....
Last edited by Heater on Sat Dec 31, 2016 10:37 am, edited 1 time in total.

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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Sat Dec 31, 2016 10:10 am

What I have taken away from this thread is that Dougie has a twin brother - that means THERE ARE TWO OF THEM!
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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Sat Dec 31, 2016 10:18 am

jamesh wrote:What I have taken away from this thread is that Dougie has a twin brother - that means THERE ARE TWO OF THEM!
Oh no!

This could explain how he manages to post so often :lol:

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Re: Raspberry Pi 3 with 2GB RAM playing the devil's advocate

Sat Dec 31, 2016 10:52 am

rpdom wrote:
jamesh wrote:What I have taken away from this thread is that Dougie has a twin brother - that means THERE ARE TWO OF THEM!
Oh no!

This could explain how he manages to post so often :lol:
One of them only reading posts and the other one only posting replies would explain a lot. :)

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