Messages in this thread |  | | From | Manfred Petz <> | Subject | Re: fake cache | Date | Mon, 20 May 1996 21:28:10 +0200 (MET DST) |
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> > There's this newspaper article about people manufacturing fake cache > > memory chips, and selling motherboards with these things installed. > > lmbench will show up such machines as diabolically crap performance. > > > It would be nice to have a simple diagnostic to check for this from > > inside linux. > > Its not simple to test without an Xray machine.
Some time ago, the german computer magazine c't developed a test-program which unveils such placebo hardware, and it works great.
The program determines the internal & external cache sizes, the type of cache (write through/back), the cache speed and whether the dirty-tag-RAM is installed & working or not. This is done with a series of rep stos/movs[bdw] operations, I guess (I don't have the sources available now, so I can't tell you exactly).
If the board contains fake caches, the test-program will display a cache size of zero.
Hmm... Could this be included for /proc/cpuinfo? If yes, I'd take a look at the source and check whether it's possible to do similar checks at system startup, ask c't for permission and give it a try. :) Maybe for 2.1.x?
pm
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