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by ejolson
Fri Sep 20, 2019 7:51 pm
Forum: General discussion
Topic: Pi4 Sysbench results
Replies: 14
Views: 1959

Re: Pi4 Sysbench results

The speedup is very strange I've been building my own versions of gcc version 9.2 in an attempt to figure out what is going on. I made two builds: One with the flags ../gcc-9.2.0/configure -v --enable-languages=c,c++,fortran \ --prefix=/usr/local/gcc-9.2-v6 --enable-shared --disable-multilib \ --en...
by ejolson
Fri Sep 20, 2019 4:50 pm
Forum: General discussion
Topic: posting or replies blocked [SOLVED]
Replies: 13
Views: 260

Re: posting or replies blocked

I can't figure what you mean by that. Removed that comment to avoid confusion, although that will probably only add to it. Why would the variable name phValue be off limits but phvalue fine? Is there a well-known malware that measures hydrogen-ion concentrations? Was the filtering the result of a m...
by ejolson
Fri Sep 20, 2019 4:26 am
Forum: Troubleshooting
Topic: External drive won't mount automatically after reboot
Replies: 3
Views: 106

Re: External drive won't mount automatically after reboot

Why not automatically? It may be a problem with how systemd runs the init services. Someone else may understand things enough to fix them properly, but not me. I would place something like ( sleep 5 echo Mounting everything in fstab... mount -a echo ...done ) & in /etc/rc.local and then focus on mo...
by ejolson
Fri Sep 20, 2019 4:10 am
Forum: General discussion
Topic: Slurm: After reboot nodes are in state = down
Replies: 1
Views: 46

Re: Slurm: After reboot nodes are in state = down

Hi, I'm working with slurm-wlm 18.08.5-2 on Raspberry Pi Cluster: - 1 Pi 4 as manager - 4 Pi 4 nodes This work fine. But after every restart of the nodes I get this cluster@pi-manager:~ $ sinfo PARTITION   AVAIL  TIMELIMIT  NODES  STATE NODELIST devcluster*    up   infinite      4   down pi-4-node-...
by ejolson
Thu Sep 19, 2019 8:06 pm
Forum: General discussion
Topic: ARMv8 32-bit mode and 64-bit division
Replies: 11
Views: 535

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

64bits just encourages the compiler to use NEON more for 64-bit integer operations. This was considered costly in the past because of the long time required to move data to and from the NEON unit. Now that NEON is no longer a co-processor for armv8, that may not be the case any more. It doesn't see...
by ejolson
Thu Sep 19, 2019 5:08 pm
Forum: General discussion
Topic: ARMv8 32-bit mode and 64-bit division
Replies: 11
Views: 535

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

64bits just encourages the compiler to use NEON more for 64-bit integer operations. This was considered costly in the past because of the long time required to move data to and from the NEON unit. Now that NEON is no longer a co-processor for armv8, that may not be the case any more. It doesn't see...
by ejolson
Thu Sep 19, 2019 4:12 pm
Forum: General discussion
Topic: stuck in wifi - Debian wheezy
Replies: 11
Views: 343

Re: stuck in wifi - Debian wheezy

Thank you for your answer, I have purchased a new SD card. Would you recommend to buy a new raspberry also ? (I have a Rpi B+). Do you know the differences between B+ and newer version such as Pi 4 ? (in addition to embedded wifi) If the B+ was working well for what you want, I see no reason to cha...
by ejolson
Thu Sep 19, 2019 3:46 pm
Forum: Advanced users
Topic: Where can I hire a Raspberry Pi expert to solve random hang problems
Replies: 11
Views: 515

Re: Where can I hire a Raspberry Pi expert to solve random hang problems

"I would be suspicious first of all in the custom hardware you have attached to the Pi0, and perhaps the software that is driving it. Is there any way you can test without it?" I leave a RPi Zero disconnected from the hardware and it fails with the same problem (faulty reset with dirty bit and hang...
by ejolson
Thu Sep 19, 2019 3:41 am
Forum: Mathematica
Topic: A writing on the development of mathematical systems
Replies: 4
Views: 1724

Re: A writing on the development of mathematical systems

In the DOS days there also was the ingenious "Derive", which used amazingly few resources and probably would fly on the Pi. Comprehensive list here: https://en.wikipedia.org/wiki/List_of_computer_algebra_systems Amazingly there still seems to be an active Derive users group at http://www.austromath...
by ejolson
Thu Sep 19, 2019 3:16 am
Forum: General discussion
Topic: Pi 4 - Buster: openCV 4.1.1 stuck at 100% for like 3 hours
Replies: 2
Views: 100

Re: Pi 4 - Buster: openCV 4.1.1 stuck at 100% for like 3 hours

I rebooted my pi, deleted the contents of build and used make this time instead of make -j4 . it completely skipped the part where I was stuck last time and I was able to install openCV 4.1.1 Hopefully this will help someone else who follows that guide and faces the same issue. That's good to know....
by ejolson
Thu Sep 19, 2019 2:28 am
Forum: Other programming languages
Topic: ScriptBasic
Replies: 1368
Views: 54351

Re: ScriptBasic

I ended up installing Raspian 32 bit on my new RPI 4B 4GB. With the RPI 4B I'm getting full use with my screen. pi@raspberrypi:~ $ free -h total used free shared buff/cache available Mem: 3.8Gi 291Mi 3.1Gi 79Mi 479Mi 3.3Gi Swap: 99Mi 0B 99Mi pi@raspberrypi:~ $ df -h Filesystem Size Used Avail Use% ...
by ejolson
Thu Sep 19, 2019 1:35 am
Forum: General discussion
Topic: stuck in wifi - Debian wheezy
Replies: 11
Views: 343

Re: stuck in wifi - Debian wheezy

Thanks for your answer. I have installed Wheezy in 2014, and my raspberry was very usefull for power energy meter and plug distance control. I had some trouble to set up all these softwares as I am not a programming expert. I understand that I have to upgrade Raspbian from Wheezy to Buster (and not...
by ejolson
Wed Sep 18, 2019 5:35 pm
Forum: General discussion
Topic: Power over Ethernet and Fan
Replies: 9
Views: 183

Re: Power over Ethernet headed

"Someone" already has. "Someone" is RPT, and it's called the Raspberry Pi PoE HAT. :lol: :roll: I was aware the POE hat has a inbuilt fan. That's why I wondered whether those pins could be used more simply just for the sake of powering a fan. I took a look at the PoE HAT that I have. I don't think ...
by ejolson
Wed Sep 18, 2019 4:16 pm
Forum: General discussion
Topic: stuck in wifi - Debian wheezy
Replies: 11
Views: 343

Re: stuck in wifi - Debian wheezy

To the person making the original post, is it possible you are trying to run two copies of wpa_supplicant? I think the reason some people are still using Raspbian Wheezy is because they were following tutorials that broke when systemd was made default. I recently installed 32-bit antiX Linux on a nu...
by ejolson
Wed Sep 18, 2019 3:48 pm
Forum: General discussion
Topic: Power over Ethernet and Fan
Replies: 9
Views: 183

Re: Power over Ethernet headed

I suppose someone could design a HAT or other add-on board that would take power from those pins and convert it to something a fan could run on, but it would still only work if the Pi was connected to a PoE switch. "Someone" already has. "Someone" is RPT, and it's called the Raspberry Pi PoE HAT. :...
by ejolson
Wed Sep 18, 2019 3:33 pm
Forum: General discussion
Topic: Power over Ethernet and Fan
Replies: 9
Views: 183

Power over Ethernet and Fan

I was reading the thread

https://www.raspberrypi.org/forums/view ... 2&t=251977

and wondered if it is possible to power a fan by connecting it to the POE header. Does anyone know?
by ejolson
Wed Sep 18, 2019 4:42 am
Forum: General discussion
Topic: VPN
Replies: 6
Views: 164

Re: VPN

Which one is free lol Both are free. I would use WireGuard or IPsec for hardening a local area network and either OpenVPN or an ssh tunnel to connect remote through the Internet. I recently tested WireGuard on a number of different Raspberry Pi models and was favorably impressed. Details are at htt...
by ejolson
Wed Sep 18, 2019 3:59 am
Forum: Mathematica
Topic: Bugs in Mathematica on Raspberry Pi 3?
Replies: 2
Views: 9347

Re: Bugs in Mathematica on Raspberry Pi 3?

I wrote some Mathematica code reading data fast from a TCP device. It works reliably under 10.3.1 but not version 11 or 12. Any idea idea how to install version 10.3 now? "sudo apt-get install wolfram-engine" installs version 12.0.1 and "apt-cache madison wolfram-engine" only shows that version as ...
by ejolson
Tue Sep 17, 2019 5:35 pm
Forum: General discussion
Topic: trying to buy more than 1 pi zero
Replies: 18
Views: 497

Re: trying to buy more than 1 pi zero

You can go to places like micro center, you can keep buying one for $5 but you have to go around and get back in line. if the cashier is nice they will ring up to 2 separate. or if you have multiple accounts you can buy one for 2 separate accounts etc work/home. Over all I think @ $5 each... they a...
by ejolson
Tue Sep 17, 2019 4:46 pm
Forum: General discussion
Topic: trying to buy more than 1 pi zero
Replies: 18
Views: 497

Re: trying to buy more than 1 pi zero

I didn't understand. Sorry if I have offended anyone. Unfortunately, the rationing of Pi Zero computers is frustrating for many. As with bread in former communist countries, when anything is produced to be sold below market equilibrium prices, shortages and rationing follow. What I find strange is ...
by ejolson
Tue Sep 17, 2019 2:34 pm
Forum: General discussion
Topic: Looking for a mounting solution for RPi (in case)
Replies: 12
Views: 457

Re: Looking for a mounting solution for RPi (in case)

Each individual Pi will be deployed to a different customer location. We're pretty locked in with the modular case we're using now because it allows us to block access to everything but the ethernet & power ports so that customers aren't tempted to mess with them. At my desk, I assemble them, insta...
by ejolson
Tue Sep 17, 2019 4:07 am
Forum: Advanced users
Topic: Raspberry Pi distributed computer project
Replies: 8
Views: 439

Re: Raspberry Pi distributed computer project

RedPanther wrote:
Mon Sep 16, 2019 4:34 pm
If you've made it this far into my build, I recently went through some system upgrades.
It looks like things are coming together. Are you are making your own case? What is the case made of? Is it made from wood? Or is it made with some special type of plastic?
by ejolson
Tue Sep 17, 2019 2:06 am
Forum: Networking and servers
Topic: Generic storage benchmark on RPI
Replies: 2
Views: 107

Re: Generic storage benchmark on RPI

Hi Folks, There's a lot of disk benchmarking done for SSD / SD etc and other storage using CrystalDiskMark which runs on PC. Is there an equivalent running natively on RPI raspian? It will be a better 'whole-system' test for storage performance that just testing the media on a PC without taking int...
by ejolson
Tue Sep 17, 2019 1:39 am
Forum: General discussion
Topic: A Pi Pie Chart
Replies: 112
Views: 11621

Re: A Pi Pie Chart

I'm somewhat disappointed that switching to 64-bit didn't solve the performance problems with newer compilers and merge sort. I clicked with my mouse and created an Amazon EC2 instance with 4 Graviton processors running 64-bit ARM Ubuntu Linux. For reference this is an a1.xlarge instance with 8GB R...
by ejolson
Tue Sep 17, 2019 12:09 am
Forum: General discussion
Topic: Why moving to 64bit?
Replies: 259
Views: 18187

Re: Why moving to 64bit?

Once I added -mcpu=cortex-a72, sysbench gets 10x faster in the 32-bit case to become on par with aarch64. I have tried to reproduce this result here but was unable. My understanding is that the Cortex-A72 running in 32-bit mode does not have any 64-bit registers and so can't perform any 64-bit divi...

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