headamage
Posts: 75
Joined: Wed Jan 07, 2015 9:59 am

Faulty Pi Memory

Thu Mar 12, 2015 10:57 pm

Two Pi 2, identical setup and hardware, one script that checks for prime numbers, two different results. Or rather, one of the two Pi simply crashes after a few seconds of running the script. Every time it is a different error. So far, I have recorded the following crashes: (gdrive links)

https://drive.google.com/file/d/0B6KJLG ... sp=sharing

https://drive.google.com/file/d/0B6KJLG ... sp=sharing

https://drive.google.com/file/d/0B6KJLG ... sp=sharing

To eliminate as many factors as possible, I have swapped SD cards between my two Pi 2, I have used the same PSU on both, same cables, same ethernet, same mouse and keyboard and same monitor. Basically everything is the same. Both of them are running Raspbian with the latest updates. Only one of them crashes. Any ideas? Should I just get a replacement?

jdb
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 2348
Joined: Thu Jul 11, 2013 2:37 pm

Re: Faulty Pi Memory

Fri Mar 13, 2015 8:59 am

Are you running with an overclock in /boot/config.txt?
Rockets are loud.
https://astro-pi.org

User avatar
RaTTuS
Posts: 10558
Joined: Tue Nov 29, 2011 11:12 am
Location: North West UK
Contact: Twitter YouTube

Re: Faulty Pi Memory

Fri Mar 13, 2015 9:05 am

sudo apt-get update && sudo apt-get install memtester

sudo memtester 500 10
^ 500 change to something sensible
10 is number of loops
How To ask Questions :- http://www.catb.org/esr/faqs/smart-questions.html
WARNING - some parts of this post may be erroneous YMMV

1QC43qbL5FySu2Pi51vGqKqxy3UiJgukSX
Covfefe

headamage
Posts: 75
Joined: Wed Jan 07, 2015 9:59 am

Re: Faulty Pi Memory

Fri Mar 13, 2015 9:16 am

thanks, will try this now.

headamage
Posts: 75
Joined: Wed Jan 07, 2015 9:59 am

Re: Faulty Pi Memory

Fri Mar 13, 2015 9:21 am

jdb wrote:Are you running with an overclock in /boot/config.txt?
Tried both ways. Without overclock it just takes a bit longer to get the error or it happens less frequently but it does happen. The first time it ever happened was without overclock right after noobs finished installing Raspbian, it had a kernel panic. I assumed it was no big deal since the new kernel was just released so it could have been a bug.
I am using the Pi2 overclock setting from raspi-config, I don't edit anything manually in /boot.

The script I am using does a factorial of huge numbers like 10,000! It doesn't seem to use more than 256MB of memory though. It runs 4 threads in parallel.

you can find the script here:
https://github.com/headamage/wilson-prime-finder
Last edited by headamage on Fri Mar 13, 2015 9:29 am, edited 1 time in total.

User avatar
RaTTuS
Posts: 10558
Joined: Tue Nov 29, 2011 11:12 am
Location: North West UK
Contact: Twitter YouTube

Re: Faulty Pi Memory

Fri Mar 13, 2015 9:25 am

do you ever get the power warning box or the power light flickering
How To ask Questions :- http://www.catb.org/esr/faqs/smart-questions.html
WARNING - some parts of this post may be erroneous YMMV

1QC43qbL5FySu2Pi51vGqKqxy3UiJgukSX
Covfefe

jdb
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 2348
Joined: Thu Jul 11, 2013 2:37 pm

Re: Faulty Pi Memory

Fri Mar 13, 2015 9:29 am

Please post the serial number of the dodgy Pi (from /proc/cpuinfo).
Rockets are loud.
https://astro-pi.org

headamage
Posts: 75
Joined: Wed Jan 07, 2015 9:59 am

Re: Faulty Pi Memory

Fri Mar 13, 2015 9:30 am

RaTTuS wrote:do you ever get the power warning box or the power light flickering
No, never, my PSU can support more than 2.1amps and i have good USB cables. None of my Pi ever run out of juice.

headamage
Posts: 75
Joined: Wed Jan 07, 2015 9:59 am

Re: Faulty Pi Memory

Fri Mar 13, 2015 9:31 am

jdb wrote:Please post the serial number of the dodgy Pi (from /proc/cpuinfo).
000000007ece5167

gsh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 1551
Joined: Sat Sep 10, 2011 11:43 am

Re: Faulty Pi Memory

Fri Mar 13, 2015 9:59 am

Also, is the Made in UK or Made in PRC, are the DSI / CSI connectors white or black and what's the date code on the little 3D barcode on the back?

Gordon
--
Gordon Hollingworth PhD
Raspberry Pi - Director of Software Engineering

headamage
Posts: 75
Joined: Wed Jan 07, 2015 9:59 am

Re: Faulty Pi Memory

Fri Mar 13, 2015 10:13 am

gsh wrote:Also, is the Made in UK or Made in PRC, are the DSI / CSI connectors white or black and what's the date code on the little 3D barcode on the back?

Gordon
Date on Barcode is 14/01
Says Made in the UK near the DSI.
DSI/CSI slots are all black.
Raspberry Pi 2 Model B V1.1 (under GPIO)

As of now, memtester has completed one loop without problems with 500MB allocated. It is going through the second loop now.

Scratch the above, i missed the error because the terminal window is small. Here is the result of the first loop without overclocking. Second loop also failed.

Code: Select all

pi@Pi2Black ~ $ memtester 500 20
memtester version 4.2.2 (32-bit)
Copyright (C) 2010 Charles Cazabon.
Licensed under the GNU General Public License version 2 (only).

pagesize is 4096
pagesizemask is 0xfffff000
want 500MB (524288000 bytes)
got  500MB (524288000 bytes), trying mlock ...locked.
Loop 1/20:
  Stuck Address       : ok
  Random Value        : ok
  Compare XOR         : ok
  Compare SUB         : ok
  Compare MUL         : ok
  Compare DIV         : ok
  Compare OR          : ok
  Compare AND         : ok
  Sequential Increment: ok
  Solid Bits          : setting testing  63^ok
  Block Sequential    : ok
  Checkerboard        : ok
  Bit Spread          : ok
  Bit Flip            : testing 144FAILURE: 0x00040000 != 0x00000000 at offset 0           x032b71fc.
FAILURE: 0x00040000 != 0x00000000 at offset 0x0a38a63c.
  Walking Ones        : ok
  Walking Zeroes      : ok
  8-bit Writes        : ok
  16-bit Writes       : ok

Loop 2/20:
  Stuck Address       : ok
  Random Value        : ok
  Compare XOR         : ok
  Compare SUB         : ok
  Compare MUL         : ok
  Compare DIV         : ok
  Compare OR          : ok
  Compare AND         : ok
  Sequential Increment: ok
  Solid Bits          : ok
  Block Sequential    : ok
  Checkerboard        : ok
  Bit Spread          : ok
  Bit Flip            : testing 225FAILURE: 0x00000000 != 0x10000000 at offset 0           x07b75340.
  Walking Ones        : ok
  Walking Zeroes      : testing  49

headamage
Posts: 75
Joined: Wed Jan 07, 2015 9:59 am

Re: Faulty Pi Memory

Fri Mar 13, 2015 3:00 pm

Contacted the seller and will return it for a replacement.

rpiswag
Posts: 804
Joined: Mon May 19, 2014 10:04 pm

Re: Faulty Pi Memory

Fri Mar 13, 2015 10:18 pm

Just wondering don't all pis no matter where there made need to pass a quality control test.
A computer's power can't be just measured Gigahertz. It is the same thing with us humans.

headamage
Posts: 75
Joined: Wed Jan 07, 2015 9:59 am

Re: Faulty Pi Memory

Fri Mar 13, 2015 10:33 pm

faulty memory can happen even on desktop computers, that's why they usually come with warranties for a year or two. Some come with lifetime warranty. Even if you don't overclock it, there is a chance it will develop a fault. I've had several RAM kits fail on me at random times regardless of how good the motherboard,PSU and the RAM itself. It just happens.

jdb
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 2348
Joined: Thu Jul 11, 2013 2:37 pm

Re: Faulty Pi Memory

Fri Mar 13, 2015 11:34 pm

rpiswag wrote:Just wondering don't all pis no matter where there made need to pass a quality control test.
They do.

But with a new product launch, we are ever vigilant for "test escapes" that get round our test specifications and make it into the wild with a fault. This is why you have two Raspberry Pi engineers requesting information in this thread.

Sony obsesses over "five sigma" defect-free product leaving the factory. While this is good and admirable, it does not encompass failures encountered in the field - particularly in the OP's case of a slightly unreliable Pi, the factory involvement is long since past.

The serial number/date code will tell us what procedures/test regime were in force on the day that the Pi was made. If we get multiple reports of the same fault, we may conclude that there is a hole in the test regime. At that point, we work to plug that hole.
Rockets are loud.
https://astro-pi.org

rpiswag
Posts: 804
Joined: Mon May 19, 2014 10:04 pm

Re: Faulty Pi Memory

Sat Mar 14, 2015 12:55 pm

Don't all pis (uk and prc) need to pass the same quality control test or is the tests for each Pi different? Does the pis in the uk get more strick testing compared to the ones in the prc. I am confused.
A computer's power can't be just measured Gigahertz. It is the same thing with us humans.

headamage
Posts: 75
Joined: Wed Jan 07, 2015 9:59 am

Re: Faulty Pi Memory

Sat Mar 14, 2015 1:08 pm

Give me a few minutes because I just discovered that my second Pi 2 also fails memtester although it runs my script just fine. It just failed memtest at 1Ghz but it passed at 700Mhz. Don't know what will happen at 900Mhz which I think is the factory default.

Can someone tell me what is the default clock on a Pi 2? I have been testing with the Pi 2 overclock preset in raspi-config as well as the 700Mhz preset but I thought from the factory the Pi 2 should run at 900Mhz, so I have been underclocking them when I was setting it to 700Mhz in raspi-config. I was under the false impression that if i set it to "no overclock" in raspi-config, it would default to 900Mhz rather than the 700Mhz it says in raspi-config.

So, if I want to test default clock and overclock, what should i set in raspi-config?
I will postpone the RMA until I run another series of memtests using correct clocks.
It definitely sucks that both of them fail at 1GHz. I thought it was guaranteed to work at the raspi-config presets.

User avatar
xoopha
Posts: 106
Joined: Mon Feb 09, 2015 9:52 pm

Re: Faulty Pi Memory

Sat Mar 14, 2015 1:15 pm

Edit the /boot/config.txt file and comment out/delete the "freq" parameters to achieve default speed.

User avatar
DougieLawson
Posts: 38863
Joined: Sun Jun 16, 2013 11:19 pm
Location: A small cave in deepest darkest Basingstoke, UK
Contact: Website Twitter

Re: Faulty Pi Memory

Sat Mar 14, 2015 1:22 pm

rpiswag wrote:Don't all pis (uk and prc) need to pass the same quality control test or is the tests for each Pi different? Does the pis in the uk get more strick testing compared to the ones in the prc. I am confused.
Yes and in exceedingly rare exceptional circumstances a bad device will get through. In that case the RPF really want to discover how that happens so they can enhance the device testing to prevent that in future.
Note: Any requirement to use a crystal ball or mind reading will result in me ignoring your question.

Criticising any questions is banned on this forum.

Any DMs sent on Twitter will be answered next month.
All non-medical doctors are on my foes list.

rpiswag
Posts: 804
Joined: Mon May 19, 2014 10:04 pm

Re: Faulty Pi Memory

Sat Mar 14, 2015 1:33 pm

So the tests are the same in both factory locations and all pis are tested?
A computer's power can't be just measured Gigahertz. It is the same thing with us humans.

headamage
Posts: 75
Joined: Wed Jan 07, 2015 9:59 am

Re: Faulty Pi Memory

Sat Mar 14, 2015 1:36 pm

Wait, don't assume I have a faulty Pi yet! I need to run a series of tests with proper settings. It is clear that my methodology was wrong as I was either underclocking or overclocking the Pi without ever running it at the standard 900MHz. Please give me some time.

I have manually set one of the Pi to 900MHz now and so far it has not failed memtest at the point where it usually failed before.
At this point, I don't think the problem is CPU overclocking but rather the RAM. I will do a series of tests with CPU at stock and RAM overclocked to confirm this assumption.

The only safe conclusion for now is that both my Pi fail memtest at the Pi2 overclock preset in raspi-config which i think is 1GHz CPU and 500MHz RAM. My money is on the RAM not taking 500MHz without overvolt.

The only question I have is if the overclocking preset in raspi-config is considered a guaranteed setting with no stability problems. If yes, then I have enough reason to RMA the two boards. If no, then it is just bad luck but I cannot complain nor can I claim defect. Please clarify this!

klricks
Posts: 7133
Joined: Sat Jan 12, 2013 3:01 am
Location: Grants Pass, OR, USA
Contact: Website

Re: Faulty Pi Memory

Sat Mar 14, 2015 1:47 pm

headamage wrote:...
..
The only question I have is if the overclocking preset in raspi-config is considered a guaranteed setting with no stability problems. If yes, then I have enough reason to RMA the two boards. If no, then it is just bad luck but I cannot complain nor can I claim defect. Please clarify this!
It's my understanding that NO amount of overclocking is guaranteed. Though that was my thinking for all brands, models of CPU / computer systems in general.
Unless specified otherwise my response is based on the latest and fully updated RPiOS Buster w/ Desktop OS.

headamage
Posts: 75
Joined: Wed Jan 07, 2015 9:59 am

Re: Faulty Pi Memory

Sat Mar 14, 2015 3:48 pm

update post:

the one Pi that was more stable initially and could run my hog script but failed the memtest now passes the memtest with the following settings directly into /boot/config.txt:

arm_freq=1000
core_freq=500
over_voltage=4
temp_limit=85
sdram_freq=500

Same SD card now running on the less stable Pi without errors so far. Haven't tested my hog script on it yet. Will report when I complete the round of tests.
My guess is that both my Pi need a bit extra voltage to be stable at 1GHz. Raspi-config preset for 1Ghz on Pi 2 is over_voltage=2 which isn't enough for my boards.

ssakar
Posts: 3
Joined: Wed Mar 12, 2014 8:43 am

Re: Faulty Pi Memory

Sat Mar 14, 2015 4:17 pm

I can also confirm that memtester reported errors with the default overclocking settings for the pi2 (1000,500,500, 2 overvolt). Some blog post mentions similar behavior.

headamage
Posts: 75
Joined: Wed Jan 07, 2015 9:59 am

Re: Faulty Pi Memory

Sat Mar 14, 2015 5:42 pm

ok, here is the results so far:

Both Pi at these settings pass memtester with 500MB (single pass).

arm_freq=1000
core_freq=500
over_voltage=4
temp_limit=85 #temp has never been above 60c inside a pibow coupe.
sdram_freq=500

However, one of them fails my hog program at these settings and it also fails with over_voltage=6.
So I can't go any higher on the voltage for that board without voiding warranty which I am not planning to do. I will start backing off the CPU clock to see if the problem is indeed with the CPU because memtest results suggest that it may be the CPU that can't do 1GHz.

Can people please run my mprime.py and tell me if it works on their Pi with and without overclocking? Link to script below (it won't exit cleanly if you do ctrl+c. I need to clean up the code and finish it off.)
https://github.com/headamage/wilson-prime-finder
I am using the range 10000 - 15000 with 4 cores. The "bad" Pi usually fails within a minute or two.

Return to “General discussion”