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by jahboater
Sun Sep 29, 2019 8:59 pm
Forum: General discussion
Topic: SD Card power failure resilience ideas
Replies: 15
Views: 686

Re: SD Card power failure resilience ideas

Even if you provide a mechanism to ensure the current block write completes successfully, it doesn't solve the problem that the operating system probably has a huge amount of cached filesystem changes that won't be written to SD card. While the card may be logically intact following a loss of power...
by jahboater
Sun Sep 29, 2019 8:44 pm
Forum: Other programming languages
Topic: The Rust debate.
Replies: 151
Views: 3747

Re: The Rust debate.

I don't think Rust allows you to turn off array bounds checking, at least you couldn't the last time I fought with rustc. There is significant overhead to checking every indexed access. Compare a Rust coded 2-D FFT with one coded in C. I believe there is a space overhead too - needed in some cases ...
by jahboater
Sun Sep 29, 2019 7:50 pm
Forum: Other programming languages
Topic: The Rust debate.
Replies: 151
Views: 3747

Re: The Rust debate.

Traditionally languages did not use the same compiler. ALGOL was compiled by an ALGOL compiler, Fortran by a Fortran compiler. Same for PL/M, Coral and a ton of others. Yes. Long ago Fortran was popular for running benchmarks and comparing mainframes. So the manufacturers made sure their Fortran co...
by jahboater
Sun Sep 29, 2019 10:53 am
Forum: Other programming languages
Topic: The Rust debate.
Replies: 151
Views: 3747

Re: The Rust debate.

Of course the extra strict compile time checking of Rust would make such changes immediately apparent and prevent undefined behaviors. Yes. And that's fine, the safe option. Better than Python 2/3. New features in C are introduced in such a way that existing code will still compile. Starting with C...
by jahboater
Sun Sep 29, 2019 10:43 am
Forum: Other programming languages
Topic: The Rust debate.
Replies: 151
Views: 3747

Re: The Rust debate.

But, they can have been "enhanced" to the point where they have diverged from their original roots (Yes, I'm looking at you C++ :-) ) Take a look at "modern" Fortran. If you grew up with Fortran IV like I did, you wont see much that is familiar. C seems to be ultra stable, presumably because of the...
by jahboater
Sun Sep 29, 2019 10:32 am
Forum: Other programming languages
Topic: The Rust debate.
Replies: 151
Views: 3747

Re: The Rust debate.

It difficult to compare two languages for speed. Only if both languages are supported by the same compiler is it reasonable. I am skeptical about claims that xxx safe language is faster than C. Sure certain language features might allow static checks, but that is still no faster than C which by defa...
by jahboater
Sun Sep 29, 2019 10:11 am
Forum: Other programming languages
Topic: The Rust debate.
Replies: 151
Views: 3747

Re: The Rust debate.

Some general points.... I think it's important to remember that when you compare languages one key question to bear in mind is "How long have they existed?". It's unfair to judge a new language in the same way you would an mature one. New ones can change since they don't yet have the inertia of a l...
by jahboater
Sat Sep 28, 2019 9:25 pm
Forum: General discussion
Topic: Raspberry Pi 4 constantly crashes and is overheating
Replies: 14
Views: 697

Re: Raspberry Pi 4 constantly crashes and is overheating

pcmanbob wrote:
Sat Sep 28, 2019 9:22 pm
A common cause of rebooting like you are experiencing is a power supply that is not suitable for the pi, so what are you using as a power supply ?
+1

Sorry I didn't think of that.

Use the "official" Raspberry Pi PSU, they are well known to be problem free (and are cheap!)
by jahboater
Sat Sep 28, 2019 9:17 pm
Forum: General discussion
Topic: Raspberry Pi 4 constantly crashes and is overheating
Replies: 14
Views: 697

Re: Raspberry Pi 4 constantly crashes and is overheating

I then found instructions to install Raspbian Buster, which finally allowed me to boot into the desktop and start the browser. That's progress, well done. However, as soon as I try to perform any tasks other heavier than viewing the Google homepage (e.g. viewing a video on YouTube), it now simply r...
by jahboater
Sun Sep 22, 2019 10:11 pm
Forum: Advanced users
Topic: RaspberryPi 4: heatsink or fan
Replies: 83
Views: 27100

Re: RaspberryPi 4: heatsink or fan

alphanumeric wrote:
Sun Sep 22, 2019 10:00 pm
Define normal usage? My 4B routinely hit 80c with just a browser window open to one of my surveillance camera network feeds. Heatsink no fan Pibow coupe case . Room temperature was around 24c.
Is that your PiBow case perhaps?
My 4B is at 50C just using the browser.
About 20C ambient.
by jahboater
Sun Sep 22, 2019 8:03 pm
Forum: C/C++
Topic: memory mapping and access via (mmap)
Replies: 17
Views: 783

Re: memory mapping and access via (mmap)

I am sooo close. Since imitation is the sincerest form of flattery (and I thought it would work!) I took your code and molded around what I am trying to do. And Voila, If I map 0xFE20B000 it actually compiles and runs and I can use the registers I have defined in the struct. If I tried 0xFE20B880, ...
by jahboater
Sun Sep 22, 2019 3:44 pm
Forum: Advanced users
Topic: RaspberryPi 4: heatsink or fan
Replies: 83
Views: 27100

Re: RaspberryPi 4: heatsink or fan

I was simply referring to my own experience, and the experience was the same with every other Pi, But the Pi4 is different - the first with a reduced 28nm node size. You have no relevant experience. I never have to worry about throttling, not even for an instant, and I can get the max performance o...
by jahboater
Sun Sep 22, 2019 2:24 pm
Forum: Advanced users
Topic: RaspberryPi 4: heatsink or fan
Replies: 83
Views: 27100

Re: RaspberryPi 4: heatsink or fan

but I gotta say I find it very hard to believe that the Pi 4 will handle heavy desktop use without any throttling and without any type of cooling or heatsink. As said above, the pi4 is a different chip from the pi3, with a smaller node size, you cannot compare them. There seems to be lot of people ...
by jahboater
Sun Sep 22, 2019 8:41 am
Forum: Advanced users
Topic: RaspberryPi 4: heatsink or fan
Replies: 83
Views: 27100

Re: RaspberryPi 4: heatsink or fan

From my experience of using my Raspberry Pi 3 B+ as a Desktop PC, the only thing that would completely eliminate throttling I suggest you try a Pi4 (which is also the topic of this thread). The Pi3B+ was pushing the limits of the old 40nm node size. The new Pi4 has had a die shrink to 28nm and so r...
by jahboater
Sun Sep 22, 2019 7:24 am
Forum: General discussion
Topic: Ideal SD Card Size for Raspberry PI 4
Replies: 3
Views: 244

Re: Ideal SD Card Size for Raspberry PI 4

32GB cards are now cheaper than 16GB cards .... https://www.amazon.co.uk/SanDisk-microSDHC-Memory-Adapter-Performance/dp/B073S8LQSL/ref=sr_1_3?crid=2BO877DW9VQRM&keywords=sandisk+ultra+32+gb+microsdhc+memory+card+%2B+sd+adapter+with+a1+app&qid=1568927532&sprefix=sandisk+a1+app%2Caps%2C162&sr=8-3 If ...
by jahboater
Sat Sep 21, 2019 6:00 pm
Forum: C/C++
Topic: Raspberry Pi project in c++ build on Windows
Replies: 4
Views: 272

Re: Raspberry Pi project in c++ build on Windows

I am building an C++ application for RPi but the problem is tha compiling takes too long and it is slowing me down. I am using a RPi 1. My RPi 2 is reserved for another project. The simplest answer perhaps is just to look at getting the new Pi4 model. Compiling is fast on the Pi4 for any sized prog...
by jahboater
Sat Sep 21, 2019 7:31 am
Forum: Advanced users
Topic: RaspberryPi 4: heatsink or fan
Replies: 83
Views: 27100

Re: RaspberryPi 4: heatsink or fan

To my way of thinking, why run it any hotter than you have too? I'm a lot happier knowing my temps stay at 40c instead of climbing to 80c. Cooler is better Yes definitely, cooler is better - it might last for 35 years instead of 30 years :) Mine idles in the upper 40C's. I just did a largish compil...
by jahboater
Fri Sep 20, 2019 8:26 pm
Forum: Advanced users
Topic: RaspberryPi 4: heatsink or fan
Replies: 83
Views: 27100

Re: RaspberryPi 4: heatsink or fan

If you can live with it naked, and ambient temps are not too high, mounting it vertically may work. @Jamesh reports good results running that way and I suspect he logs lots of hours with a Pi. It does work. My Pi4 will not throttle under any load, even stress tests like cpuburn. No fan is required ...
by jahboater
Thu Sep 19, 2019 9:16 pm
Forum: General discussion
Topic: ARMv8 32-bit mode and 64-bit division
Replies: 11
Views: 662

Re: ARMv8 32-bit mode and 64-bit division

Are 32GB cards now recommended or have I done something strange to make Raspbian take more storage than in should? I don't know, cards are so cheap now that I only use 64GB or 128GB. and 32GB cards are now cheaper than 16GB cards !!!!!! https://www.amazon.co.uk/SanDisk-microSDHC-Memory-Adapter-Perf...
by jahboater
Thu Sep 19, 2019 10:45 am
Forum: General discussion
Topic: ARMv8 32-bit mode and 64-bit division
Replies: 11
Views: 662

Re: ARMv8 32-bit mode and 64-bit division

Are you sure your original reported Pi 3B+ run times were accurate? Since Raspbian Buster includes gcc-4.9, gcc-5.5, gcc-6.5 and gcc-7.3 I installed and tried them all. Using variations of -mcpu=cortex-a53 -mfpu=neon-fp-armv8 -mfloat-abi=hard -mneon-for-64bits all run times are greater than 30 seco...
by jahboater
Thu Sep 19, 2019 9:57 am
Forum: Other programming languages
Topic: ScriptBasic
Replies: 1398
Views: 59839

Re: ScriptBasic

If I can't find a stable 64 bit OS, will the standard Raspian 32 OS for the RPi 4B access all 4 GB of system memory? Yes, 32-bit Raspbian can use all of the 4GB memory. It uses a special LPAE kernel. pi@pi4:~ $ free total used free shared buff/cache available Mem: 3.8Gi 334Mi 2.4Gi 97Mi 1.0Gi 3.2Gi...
by jahboater
Wed Sep 18, 2019 12:40 pm
Forum: Beginners
Topic: Can you turn off the pi 4 pwr and Ethernet lights?
Replies: 2
Views: 115

Re: Can you turn off the pi 4 pwr and Ethernet lights?

I turn the power led off by adding this to /etc/crontab

Code: Select all

@reboot root echo 0 > /sys/class/leds/led1/brightness
works on the Pi3 and the Pi4.
There must be a better way .....
by jahboater
Wed Sep 18, 2019 12:32 pm
Forum: Networking and servers
Topic: creat UDP connection
Replies: 6
Views: 198

Re: creat UDP connection

Heater wrote:
Wed Sep 18, 2019 12:31 pm
There are a million ways to do what you want.
Indeed!
Heater wrote:
Wed Sep 18, 2019 12:31 pm
Firstly, what programming language would you like to use?
The OP said Python on both sides.
by jahboater
Wed Sep 18, 2019 12:19 pm
Forum: Networking and servers
Topic: creat UDP connection
Replies: 6
Views: 198

Re: creat UDP connection

i want to create a UDP connection between two Raspberry pi, using python in both sides what i want to do. You cannot create a UDP "connection", that's not how it works. You probably want TCP (a Connection Oriented Transport Service). UDP is individual, unrelated, datagrams. Furthermore, there is no...
by jahboater
Mon Sep 16, 2019 6:07 pm
Forum: General discussion
Topic: ARMv8 32-bit mode and 64-bit division
Replies: 11
Views: 662

Re: ARMv8 32-bit mode and 64-bit division

From this post I was expecting 64-bit divisions done in 32-bit mode on the Pi 4B to be on par with 64-bit mode. What am I doing wrong? 32 bit mode has udiv and sdiv instructions from ARMv7 onwards, but they only work with 32 bit operands. In 32-bit mode, 64 bit division is done by a call to a libra...

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