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May 2, 2008

Faulty Memory

Golem has been experiencing intermittent memory problems for a little over a year, now. Originally, I ascribed the problems to cosmic rays. But their persistence seemed to belie that interpretation.

So I decided to run a memory test:

% sudo memtester 2048 1
memtester version 4.0.8 (32-bit)
Copyright (C) 2007 Charles Cazabon.
Licensed under the GNU General Public License version 2 (only).
pagesize is 4096 pagesizemask is 0xfffffffffffff000 want 2048MB (2147483648 bytes) got 2048MB (2147483648 bytes), trying mlock ...locked. Loop 1/1: Stuck Address : testing 1FAILURE: possible bad address line at offset 0x10ec6907. Skipping to next test... 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 : testing 2FAILURE: 0x00000000 != 0x01000000 at offset 0x00ec6907. Block Sequential : testing 14FAILURE: 0x0e0e0e0e != 0x0f0e0e0e at offset 0x00ec6907. Checkerboard : testing 4FAILURE: 0xaaaaaaaa != 0xabaaaaaa at offset 0x00ec6907. Bit Spread : testing 22FAILURE: 0xfebfffff != 0xffbfffff at offset 0x00ec6907. Bit Flip : testing 4FAILURE: 0x00000001 != 0x01000001 at offset 0x00ec6907. Walking Ones : testing 39FAILURE: 0xfeffffff != 0xffffffff at offset 0x00ec6907. Walking Zeroes : testing 26FAILURE: 0x04000000 != 0x05000000 at offset 0x00ec6907.
Done.

and discovered that there’s a stuck bit on one of the memory modules.

Things should be better now (no more random crashes) with new RAM installed. One thing I discovered along the way was that the version of memtester that comes with Fink is incapable, at least on PPC hardware, of testing more than 2GB of RAM. (Use a number larger than 2048 in the above, and you get a slew of malloc errors.)

The thing to do is download the current source, apply this patch and type

% make
% sudo make install

This will build a Universal binary, which is 64bit-enabled on G5 (and Intel Core 2/Xeon) hardware.

That’s good, because — when all the dust settles — golem will have 6.5GB of RAM. Now, if only my own memory were similarly upgradable…

Posted by distler at May 2, 2008 12:41 PM

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Re: Faulty Memory

I know what you mean about brain-upgrades. One slipped sign, and bang goes my afternoOn…

Posted by: James Ettle on May 6, 2008 8:48 AM | Permalink | Reply to this
Read the post A Brief History of Golem
Weblog: Musings
Excerpt: Three generations of computer, one domain name.
Tracked: April 21, 2010 3:54 PM

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