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IBM Announces First Linux-only Mainframes
A reader writes "The new Z-series mainframe for Linux, which costs $400,000 and is aimed at processing transactions at large businesses, is IBM's first mainframe computer sold without IBM's traditional z/OS mainframe operating system. More info at the IBM zSeries page" This is something that IBM and others of Big Iron vendors of *NIX have said - as Linux grows in maturity, they want to replace their *NIX with Linux. However, there's still work to be done in that area.
MIPS = Meaningless Indicator of Processor Speed
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The mainframe is MIPS per CPU, so the 16-way box is 16*120. Also, 120 MIPS is slow these days for a mainframe.
Write a simple memory intensive program and try it on a mainframe and try it on a PC. I guarantee that you won't get 3000 MIPS out of a desktop, even if the data fits in cache. Many reasons for this....
The s390 ISA is definitely CISC, you can copy a whole string with MVCL, that count's as one instruction. Do this on RISC machines and it might take a loop and execute dozens of instructions. Hence "Meaningless
About 2 years ago I wrote some C code to recursively quicksort 20M random integers and tried it on a bunch of platforms. A mainframe that was about 1 cycle behind fastest available gave me about the same single processor performance as a 1GHz PC, both a little slower than Alpha.
The big differentiator is memory architecture. How much time do you lose for a cache miss? Most processors only operate at 20-30% of theoretical maximum speed on big problems.
Memory speed has not kept up, that 2GHz box you dream about is not twice as fast as a 1GHz box, particularly if you're crunching a lot of data.
The average 16 processor mainframe is a 120 MIPS machine, whereas the average 1.5 GHz desktop system is a 3000 MIPS machine.
Mainframes run up to about 200 MIPS per processor and with multi-processor overhead a 16-way zSeries tops out somewhat below 3,000 MIPS. These are mainframe MIPS, not what you get as BogoMIPS out of Linux at boot (AFAIK, this is some quick integer timing loop calculation). There's a reason it's called BogoMIPS, troll.
IBM has successfully run over 40,000 Linux images on a mainframe (under VM). Try that on your 1.5Ghz desktop. Ever heard of Transactions Per Second (TPS) in four and five figures, I/O rates in GB/sec, multi-terabyte databases, 99.999% uptime for years? That's mainframe territory, and I sincerely doubt that you've ever seen it, or ever will.