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by jahboater
Tue Mar 15, 2016 5:03 pm
Forum: General discussion
Topic: Pi3 incorrect results under load (possibly heat related)
Replies: 105
Views: 55255

Re: Pi3 incorrect results under load (possibly heat related)

Just a quick consideration but could compile flags have a influence on the calculations and / or checks ? Possibly, but only after a re-compilation. The problem here is related to over heating and the effectiveness of the throttling mechanism. UPDATE: With very aggressive cooling (80mm fan blowing ...
by jahboater
Mon Mar 14, 2016 11:35 pm
Forum: General discussion
Topic: Pi3 incorrect results under load (possibly heat related)
Replies: 105
Views: 55255

Re: Pi3 incorrect results under load (possibly heat related)

I looked at the code but unfortunately don't know ARM assembler very well. It appears to be an infinite loop that doesn't compute any residual to detect errors. If this understanding is correct, then this test provides no way to know whether computational errors were made in the cases when the syst...
by jahboater
Mon Mar 14, 2016 8:27 pm
Forum: General discussion
Topic: Pi3 incorrect results under load (possibly heat related)
Replies: 105
Views: 55255

Re: Pi3 incorrect results under load (possibly heat related)

This stress test code is all NEON and uses all four cores. On a Pi3 with no heatsink it either crashes the system within a few seconds (and about 75C) or carries on and throttles back. The Pi3 is at stock frequency settings. With a heatsink it always successfully throttles. wget https://raw.githubus...
by jahboater
Mon Mar 14, 2016 1:54 pm
Forum: Raspbian
Topic: Raspbian's new insanely bad design decision: DHCP Static IPs
Replies: 76
Views: 18429

Re: Raspbian's new insanely bad design decision: DHCP Static

I object to the new system because dhcpcd is hard to pronounce :-) Having to specify "manual" to get the new fully automated DHCP setup is weird. Having to set configure a static IP address in a DHCP conf file is just crazy. The "manual" bit is set by default nowadays, I only ever edit dhcpcd.conf t...
by jahboater
Sun Mar 13, 2016 2:33 pm
Forum: General discussion
Topic: Pi 3 Power Supply
Replies: 11
Views: 2264

Re: Pi 3 Power Supply

I think the voltage was deliberately set to 5.1V instead of 5.2V for compatibility with older Pi's. There are various other improvements in the Pi3 supply - lower ripple and noise, improved efficiency, thicker wire in the cable. It is well engineered. Yes, but none of the changes make it less suita...
by jahboater
Sun Mar 13, 2016 2:05 pm
Forum: General discussion
Topic: Pi 3 Power Supply
Replies: 11
Views: 2264

Re: Pi 3 Power Supply

klricks wrote:nonsense......
I think the voltage was deliberately set to 5.1V instead of 5.2V for compatibility with older Pi's.

There are various other improvements in the Pi3 supply - lower ripple and noise, improved efficiency, thicker wire in the cable. It is well engineered.
by jahboater
Sun Mar 13, 2016 11:25 am
Forum: Advanced users
Topic: Overclocking
Replies: 1125
Views: 605844

Re: Overclocking

AIUI 2.5A allows for a full set of peripherals. In my current (pun intended) experience the cable gauge (thickness) is the limiting factor, thin cables lose too much voltage way before reaching 2A. I see the Official Pi3 supply uses very thick cable (18AWG) up from 20AWG for the old 2A official sup...
by jahboater
Sun Mar 13, 2016 10:57 am
Forum: General discussion
Topic: Setup static ip is not working
Replies: 4
Views: 1394

Re: Setup static ip is not working

In Jessie its in /etc/dhcpcd.conf
Add something like this to the end:

Code: Select all

interface eth0
static ip_address=192.168.1.101/24
static routers=192.168.1.1
static domain_name_servers=8.8.8.8 192.168.1.1 8.8.4.4
by jahboater
Sat Mar 12, 2016 7:17 pm
Forum: Beginners
Topic: Copy img 4gb to 8gb
Replies: 20
Views: 2368

Re: Copy img 4gb to 8gb

It lists all the packages installed, their version number, and a brief description.
Try it and see if it does what you want!

In particular try: "dpkg -l | grep xmbc" to just detail the package of interest.
by jahboater
Sat Mar 12, 2016 7:01 pm
Forum: Beginners
Topic: Copy img 4gb to 8gb
Replies: 20
Views: 2368

Re: Copy img 4gb to 8gb

Try

Code: Select all

dpkg -l
by jahboater
Thu Mar 10, 2016 11:46 pm
Forum: General discussion
Topic: RPi 3 SoC at nearly 100 °C, reporting 80 °C
Replies: 238
Views: 99981

Re: RPi 3 SoC at nearly 100 °C, reporting 80 °C

I saw this somewhere, its nearly all NEON instructions and it heats up the SoC very rapidly until it throttles back - even with a heatsink.

Code: Select all

wget https://raw.githubusercontent.com/ssvb/cpuburn-arm/master/cpuburn-a53.S
gcc -o cpuburn-a53 cpuburn-a53.S
./cpuburn-a53
by jahboater
Thu Mar 10, 2016 5:23 pm
Forum: Troubleshooting
Topic: Pi3 wifi dies - Solved
Replies: 15
Views: 6899

Re: Pi3 wifi dies - Solved

Mine said that (power management still on), but the problem appeared to be fixed.
by jahboater
Wed Mar 09, 2016 7:47 pm
Forum: Troubleshooting
Topic: RPi 3 - Very poor wifi performance
Replies: 77
Views: 121320

Re: RPi 3 - Very poor wifi performance

The latest rpi-update kernel now disables power saving by default. If you have had issues, the please remove any current workarounds and try the rpi-update firmware/kernel and report if it works for you. Hi Dom, I applied the update and it works for me. I had longish and erratic ping times (say 60-...
by jahboater
Wed Mar 09, 2016 5:31 pm
Forum: Troubleshooting
Topic: Pi3 wifi dies - Solved
Replies: 15
Views: 6899

Re: Pi3 wifi dies

You could try turning off power save

Code: Select all

iwconfig wlan0 power off
by jahboater
Wed Mar 09, 2016 8:19 am
Forum: Beginners
Topic: Underclocking my pi3 to 900mhz
Replies: 12
Views: 21791

Re: Underclocking my pi3 to 900mhz

Well i kinda liked wlan and bluetooth being integrated on the board for saving space in the case and i was told the armv8 processor also works a bit more efficient at the same clockspeed than the armv7 of the pi2 so i thought for heating issues ill clock it down to the speed of the pi2 and keep the...
by jahboater
Tue Mar 08, 2016 4:27 pm
Forum: Python
Topic: Music player that manipulates frequencies
Replies: 5
Views: 1002

Re: Music player that manipulates frequencies

Disk space is so cheap now, I just use flac.
by jahboater
Tue Mar 08, 2016 3:46 pm
Forum: Beginners
Topic: Underclocking my pi3 to 900mhz
Replies: 12
Views: 21791

Re: Underclocking my pi3 to 900mhz

ok so i schould not write something with overvolt -1? im asking because overvolt is common if overclocking to certain speeds and negative overvolt too i think? or is it just that i would have to underclock it further before starting to undervolt it? When I tried "over_voltage=-1" it failed to boot ...
by jahboater
Tue Mar 08, 2016 3:34 pm
Forum: Advanced users
Topic: Winging a Pi 3 overclock
Replies: 69
Views: 19112

Re: Winging a Pi 3 overclock

Have a look at bcmstat.sh as well.
https://raw.githubusercontent.com/Milho ... bcmstat.sh
Lots of info and in colour too.
by jahboater
Tue Mar 08, 2016 9:15 am
Forum: Beginners
Topic: Underclocking my pi3 to 900mhz
Replies: 12
Views: 21791

Re: Underclocking my pi3 to 900mhz

Well i kinda liked wlan and bloetooth being integrated on the board for saving space in the case and i was told the armv8 processor also works a bit more efficient at the same clockspeed than the armv7 of the pi2 so i thought for heating issues ill clock it down to the speed of the pi2 and keep the...
by jahboater
Mon Mar 07, 2016 8:42 am
Forum: General discussion
Topic: Benchmarking a raspberrypi compared to my own PC [obsolete and locked]
Replies: 51
Views: 19534

Re: Benchmarking a raspberrypi compared to my own PC

Result for i7-3770 using 32-bit "Integer" (gcc 5.3). Found a total of 664579 primes (32-bit) real 0m1.063s user 0m1.060s sys 0m0.000s Found a total of 664579 primes (32-bit) real 0m0.975s user 0m0.972s sys 0m0.000s Found a total of 664579 primes (32-bit) real 0m0.976s user 0m0.976s sys 0m0.000s Sadl...
by jahboater
Sun Mar 06, 2016 7:10 pm
Forum: Beginners
Topic: Raspberry Pi+ Ubuntu
Replies: 4
Views: 798

Re: Raspberry Pi+ Ubuntu

jamesh wrote:Might be worth trying Raspbian instead of Ubuntu - better support here.
Yes - and ssh is enabled by default on Raspbian.
Ubuntu is a derivative of Debian.
So is Raspbian (as its name suggests) but with special optimizations for the Pi hardware, and masses of community support.
by jahboater
Sun Mar 06, 2016 11:09 am
Forum: General discussion
Topic: Pi3 speed compared to Pi2
Replies: 91
Views: 17445

Re: Pi3 speed compared to Pi2

The results for the prime.c program show that adding the appropriate -mcpu and -mfpu options for the Pi 2B and Pi 3B result in respectively 3.8 and 4.9 times faster run times compared to the same program running on the same hardware compiled using only -O3 optimization and the default hardware targ...
by jahboater
Sun Mar 06, 2016 10:22 am
Forum: General discussion
Topic: Pi3 speed compared to Pi2
Replies: 91
Views: 17445

Re: Pi3 speed compared to Pi2

If I'm building for RPi2B I've got -mcpu=cortex-a7 -mfpu=neon-vfpv4 -mfloat-abi=hard -mtls-dialect=gnu2 what options should I use to build and optimise the code for an RPI3B (without going 64 bit)? You can change the "cortex-a7" to "cortex-a53" but it wont make much difference. The fpu options rema...
by jahboater
Sun Mar 06, 2016 9:58 am
Forum: General discussion
Topic: Pi3 speed compared to Pi2
Replies: 91
Views: 17445

Re: Pi3 speed compared to Pi2

I think on x86 GCC is pretty good at detecting the exact processor type. Using "-march=native" produces identical code on my x86 to "-march=ivybridge" for example. On ARM it is not, and defaults to the lowest common denominator. I also found a larger variance in the code produced by different compil...
by jahboater
Sat Mar 05, 2016 6:08 pm
Forum: General discussion
Topic: Pi3 speed compared to Pi2
Replies: 91
Views: 17445

Re: Pi3 speed compared to Pi2

The reported i7-6700K 4.0 GHz speed of 0.6 seconds seems surprisingly fast to me. While it is a different compiler using additional -msse2 -mfpmath=sse optimization settings, it would be great if someone else with similar hardware could obtain similar timings. Alternatively, could the test could be...

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