Skip to the Main Content

Note:These pages make extensive use of the latest XHTML and CSS Standards. They ought to look great in any standards-compliant modern browser. Unfortunately, they will probably look horrible in older browsers, like Netscape 4.x and IE 4.x. Moreover, many posts use MathML, which is, currently only supported in Mozilla. My best suggestion (and you will thank me when surfing an ever-increasing number of sites on the web which have been crafted to use the new standards) is to upgrade to the latest version of your browser. If that's not possible, consider moving to the Standards-compliant and open-source Mozilla browser.

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.

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

TrackBack URL for this Entry:

1 Comment & 1 Trackback

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

Post a New Comment