Go to advanced search

by ejolson
Tue Jun 25, 2019 12:45 am
Forum: General discussion
Topic: Is the new Raspberry Pi 4 vulnerable to Meltdown and Spectre attacks?
Replies: 12
Views: 689

Re: Is the new Raspberry Pi 4 vulnerable to Meltdown and Spectre attacks?

There was an interesting note on how effective these attacks could be last year: In fact, I doubt we will ever see a lot of in-the-wild malware using the Meltdown or Spectre exploits. Memory-read attacks simply aren't that attractive to most attackers: they don't allow an attacker to run arbitrary ...
by ejolson
Mon Jun 24, 2019 10:42 pm
Forum: General discussion
Topic: Is the new Raspberry Pi 4 vulnerable to Meltdown and Spectre attacks?
Replies: 12
Views: 689

Re: Is the new Raspberry Pi 4 vulnerable to Meltdown and Spectre attacks?

It should be as it uses the A72, the OS or whatever may stop that. According to Wikipedia ARM has reported that the majority of their processors are not vulnerable, and published a list of the specific processors that are affected. The ARM Cortex-A75 core is affected directly by both Meltdown and S...
by ejolson
Mon Jun 24, 2019 6:28 pm
Forum: General programming discussion
Topic: Raspberry Pi Benchmarks
Replies: 128
Views: 81984

Re: Raspberry Pi Benchmarks

Raspberry Pi 4 Benchmarks I have run all of my relevant benchmarks and stress tests on the new Raspberry Pi 4. The early opportunity to run the programs was due to my acceptance of the request for me to become a volunteer, exercising the system prior to launch. I will be posting results here shortl...
by ejolson
Mon Jun 24, 2019 10:05 am
Forum: General discussion
Topic: Raspberry Pi 4 Thread - general discussion
Replies: 279
Views: 12451

Re: Raspberry Pi 4 Thread - general discussion

Mostly the same, but mo' better, just how we like it. Under the skin, much is different. This is the biggest HW change in Pi history. The new hardware seems pretty much what people have been asking for. A few questions: 1. Are all the USB ports behind an internal hub or can some of them function in...
by ejolson
Sun Jun 23, 2019 10:43 pm
Forum: General discussion
Topic: Colocation between users (the cheap way)
Replies: 10
Views: 315

Re: Colocation between users (the cheap way)

About the legal issues, as soon as I am aware (myself or via a third party) that some illicit activity is taking place, I would need to intervene and stop it. Then talking to the owner for its review and solution would suffice. Unfortunately, the way you might become aware of illicit activity is fo...
by ejolson
Sun Jun 23, 2019 9:58 pm
Forum: General discussion
Topic: Colocation between users (the cheap way)
Replies: 10
Views: 315

Re: Colocation between users (the cheap way)

Cheers! What you describe is technically possible and attractive due to the low power requirements of the Pi. However, the idea is also fraught with peril. For example, avoiding financial transactions may keep you within the contract for home internet service, but that same contract may also make y...
by ejolson
Sun Jun 23, 2019 12:14 pm
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

Suspecting it might be useful to be able to calculate Fibonacci numbers other than F(4784969) I added an input box to my online Fibonacci calculator. It's rough and ready and I suspect it has a memory leak, might hang up if you calculate big fibos too often without reloading. It breaks the challeng...
by ejolson
Sat Jun 22, 2019 9:52 pm
Forum: Networking and servers
Topic: rpi2 with 3 ethernet
Replies: 3
Views: 390

Re: rpi2 with 3 ethernet

Hello Guys can you point me towards how can I add 2 more ethernet ports to RPI 2 board? USB nics are not an option and we need an enclosure for this solution any help will be appreciated Since the built-in Ethernet port is connected through USB, I'm not sure why USB is not good for the other two. I...
by ejolson
Sat Jun 22, 2019 12:34 pm
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

ejolson, Any help getting Node.js installed on the Pi and where to find four different codes is welcome. I suggest not installing node.js using "apt-get". The node version installed by Debian/Raspbian is always ancient. My favorite way to install node is via the Node Version Manager (NVM) script: h...
by ejolson
Sat Jun 22, 2019 11:39 am
Forum: General discussion
Topic: My Raspberry Home Server
Replies: 7
Views: 435

Re: My Raspberry Home Server

I know Hackers are a real problem. But are they over emphasized. Untitled.png Since about the 1st of May there have been almost 2500 attempts to access my network with the use of ssh. This is not the complete truth because my fail2ban setup has no mercy and blocks forever at the first attempt. What...
by ejolson
Sat Jun 22, 2019 11:17 am
Forum: General discussion
Topic: Weird USB slowdown on 3B+
Replies: 2
Views: 440

Re: Weird USB slowdown on 3B+

I have 3.5" EXT4-formatted HD in an externally-powered USB enclosure attached to a Pi 3B+ running the latest Raspian Stretch Lite. If I flash a new SD card, I'll see a sustained large-file transfer rate of over 35MB/sec (280 Mbit/sec) to/from the hard drive.But after some hours or days, the best-ca...
by ejolson
Fri Jun 21, 2019 11:04 pm
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

That should now reflect running AIR's fibo. 38 seconds on my RPi 3B. Unfortunately that version may leak too much memory to complete the fibench test run of computing 1000 big Fibonacci numbers without crashing. When I'm done traveling and back where I can reboot the Pi if necessary, I would be hap...
by ejolson
Fri Jun 21, 2019 9:43 pm
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

Did BASIC already have its turn? Because the original thread was called Why Avoid Basic, there have been lots of Fibonacci codes written in that language. In particular https://www.raspberrypi.org/forums/viewtopic.php?f=31&t=240287&start=25#p1472365 contains runs of two different line-numbered code...
by ejolson
Fri Jun 21, 2019 8:34 pm
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

After traveling I'm no longer in the high desert. There are no wild horses, only cows. I couldn't see due to clouds but suspect the phase of the moon may about be to change. Before a new title completely ruins this thread, I was looking to round up another herd of Fibonacci codes, this time in JavaS...
by ejolson
Thu Jun 20, 2019 11:06 pm
Forum: Teaching and learning resources
Topic: Scratch 3.0 please fix it NOW
Replies: 36
Views: 1137

Re: Scratch 3.0 please fix it NOW

It'll get done when it gets done, but as always, we do not announce when stuff will be done in advance. While offline is very good, especially in places where internet access is unavailable or slow, the online version of Scratch is popular. If the developers are not cooperative in making version 3 ...
by ejolson
Thu Jun 20, 2019 4:22 pm
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

Here is a plot showing the detail of the previous graph for n>1000000.

Image

All timings were performed using the Raspberry Pi Zero.

The red line again reminds me of the fifth title scheduled for this thread: The New Paper Tape Project.
by ejolson
Thu Jun 20, 2019 2:36 pm
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

Is AIR's newfibo the mystery while loop version? The exact C code appears as method4.c above. You can check for yourself how close it is to the newfibo ScriptBasic program. My intention was to make the codes comparable. To determine how the extension module affects performance, you could try the fo...
by ejolson
Thu Jun 20, 2019 1:43 pm
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

ejolson, Where is that red line going? Your graphs seem to show that the recursive doubling aka hfibo has a massive overhead compared to the others. It's 10 times slower for small n. But the the curve goes up at a lesser slope and is converging with the others for big n. I'm guessing that slope doe...
by ejolson
Thu Jun 20, 2019 1:31 am
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

This post is a continuation of the previous. Here is a table showing how long it takes to compute the 4784969th Fibonacci number for the previously described methods. Method T(4784969) -------------------------------- recursive doubling 13.487 sec mystery while loop 6.1586 sec golden ratio 5.4110 se...
by ejolson
Thu Jun 20, 2019 1:10 am
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

I just rounded up four distinctly different algorithms in C using the GNU Multi-precision Library. This post presents four different C codes implementing four different algorithms for quickly computing the n-th Fibonacci number. The codes are method1.c -- optimized doubling : The optimized form of ...
by ejolson
Thu Jun 20, 2019 12:01 am
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

Notice that the time taken by Javascript to print the result totally over shadows the fibo calculation time anyway, so this is all a bit moot. In a way similar to writing too many different Fibonacci codes in JavaScript, I just rounded up four distinctly different algorithms in C using the GNU Mult...
by ejolson
Wed Jun 19, 2019 5:54 pm
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

Well, there is only one WHILE loop in AIR's 1millfibo.sb, it loops around 4,784,969 times Are you sure? Theoretically the doubling formulas should take about 23 iterations when n=4784969 and the second case in that while loop adds no more than double that. For all algorithms it would be interesting...
by ejolson
Wed Jun 19, 2019 5:35 pm
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

ejolson, I thought we decided earlier that no memory leaks are possible in Linux because all user memory is freed by the operating system after the program crashes. Ha! Depends what you mean by memory leak. I took a look under my PC and did not find any memory puddles on the floor. I wonder whether...
by ejolson
Wed Jun 19, 2019 5:26 pm
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

To be accurate fibo() gets calls get nested to a recursion depth of 24 where as it actually gets called 7,472,783 times! And you don't see that as a problem? How many WHILE loops do you think AIR's Fibo takes to come up with an answer? Most of those calls are to compute Fibonacci numbers for small ...
by ejolson
Wed Jun 19, 2019 4:52 pm
Forum: General programming discussion
Topic: A Final Fibonacci Challenge
Replies: 601
Views: 18055

Re: A Final Fibonacci Challenge

No, the problem is managing the memory allocation of all those huge numbers and strings. (Unless of course one is trying to keep megabyte sized objects on the stack itself!) An example of code that keeps all those megabyte-sized big numbers on the stack would be parallel.c and fibompi.c. If nothing...

Go to advanced search