Linked by Thom Holwerda on Thu 26th Aug 2010 23:24 UTC
IBM At the Hot Chips 2010 conference, IBM announced their upcoming z196 CPU, which is really, really fast. How fast? Fastest chip in the world fast. Intended for Z-series mainframe computers, the Z196 has a clock speed of 5.2GHz. Measuring just 512 square millimeters, the Z196 is fabricated on 45nm PD SOI technology, and on its surface contains almost one and a half billion transistors. My... Processor is bigger than yours.
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Slooooow cpu.
by jeepercreeper on Sun 29th Aug 2010 21:00 UTC
jeepercreeper
Member since:
2010-08-29

As someone explained on the internet: This cpu is really slow. Two arguments:

The predecessor, the z10 Mainframe cpu, is really slow. A fully configured z10 Mainframe with 64 cpus gives 28.000 MIPS. This equals 437 MIPS / cpu.

This new IBM z196 cpu the article talks about, is 50% faster than the z10 cpu. Which means the new z11 Mainframe gives in total 42.000 MIPS with 64 of these z196 cpus. This means this "new million dollar fastest cpu in the world" z196 cpu, gives ~650 MIPS.

(A) If you emulate an Mainframe on an 8-socket Intel Nehalem-EX server, you get 3.200 MIPS:
http://en.wikipedia.org/wiki/TurboHercules#Performance

This equals 400 MIPS / Nehalem-EX. But remember, software emulation is 5-10x times slower. In reality, the Nehalem-EX gives 2000-4000 MIPS. Hence, you need 10 Nehalem-EX cpus to reach 40.000 MIPS, in par with the new z11 Mainframe which gives 42.000 MIPS.

Hence, any modern x86 cpu is 5-10x faster than this z196 cpu. You need 10 Intel Nehalem-EX to match 64 of the IBM z196.

(B) A linux developer that ported Linux to IBM Mainframes said that 1 MIPS equals 4 MHz x86:
http://www.mail-archive.com/linux-390@vm.marist.edu/msg18587.html

This means an 2GHz Intel Nehalem-EX with 8 cores, has in total 16 GHz. This equals 4.000 MIPS. Hence you need 10 Nehalem-EX to reach 40.000 MIPS.

We have two independent experts saying that any modern x86 is 5-10x faster than this z196 Mainframe cpu. Which runs 5 GHz and has 376 MB cache (L1 + L2 + L3). And still any old x86 with half the Hz and one tenth of the cache, is much faster than this z196 cpu that costs million dollars.

Reply Score: 0

RE: Slooooow cpu.
by JAlexoid on Sun 29th Aug 2010 23:45 in reply to "Slooooow cpu."
JAlexoid Member since:
2009-05-19

You should read up what mainframes are used for and where is their strength and the reason for using them. Otherwise, you popping up and comparing plain CPU power is just ridiculous.

PS: You'll notice that the "fastest" is the clock frequency here, not MIPS or some other measure.

Reply Parent Score: 2

RE: Slooooow cpu.
by Nicholas Blachford on Mon 30th Aug 2010 12:13 in reply to "Slooooow cpu."
Nicholas Blachford Member since:
2005-07-06

As someone explained on the internet


Yes, because everything you read on the internet is true isn't it?

People have been saying desktops are faster then mainframes since the 80's. But big companies like banks still use mainframes, there's usually a good reason for that.

It's somewhat pointless comparing a desktop CPU to a mainframe CPU. The desktop only has a few cores and that's it. A mainframe has a whole set of different types of cores. It's a pretty much a distributed systems of dedicated processors, with the CPUs being only one of many types of core. If you want to compare performance you need to compare to ALL of the cores in the mainframe.

As someone else said, mainframes are really designed for transaction processing with huge levels of I/O. A decked out z196 goes up to 288GB/second bandwidth. That's 8x more bandwidth than your 8 core Xeon has memory bandwidth!


---

As for the cache sizes, they are:

L1
64KB Instructions
128KB data

L2
1.5MB / core

L3
24MB / shared across 4 cores

L4
192MB shared across 24 cores

That's per "book" you can add 4 books.

...and they are backwards compatible with code written in the 1960's.

More info here: http://www.redbooks.ibm.com/redpieces/pdfs/sg247832.pdf

Reply Parent Score: 2

RE[2]: Slooooow cpu.
by jeepercreeper on Tue 31st Aug 2010 11:07 in reply to "RE: Slooooow cpu."
jeepercreeper Member since:
2010-08-29

If the given explanation is wrong, and if you claim this IBM Mainframe z196 cpu is really fast - then where is the error in the reasoning? Please point the errors out. If you claim that the IBM Mainframe cpus are not slow, but fast - please point out the errors so that I understand why are correct. Or do you mean I should just trust you, just because you work at IBM?

Short recap of the arguments showing why this z196 cpu is slow. This IBM z196 Mainframe CPU gives ~650 MIPS, according to IBM. Let us relate the number 650 MIPS to x86 cpu:

(A) Intel Nehalem-EX gives 400 MIPS under software emulation. Software emulation is 5-10x slower. If we ported the Mainframe code to x86, the Nehalem-EX can actually execute code worth of 2000-4000 MIPS. Hence, x86 is much faster.

(B) 1 MIPS equals 4 MHz x86. An 8-core 2GHz Nehalem-EX has 16 GHz in total. This equals 4.000 MIPS. Hence x86 is much faster.

So where are the errors in (A) and where are the errors in (B)? Please point them out.

Also, you claim that one z196 does not have up to 376 MB cache? So, no half a GB of cache?

Reply Parent Score: 1

RE[2]: Slooooow cpu.
by juwi on Tue 31st Aug 2010 14:37 in reply to "RE: Slooooow cpu."
juwi Member since:
2010-01-13

Actually IBM doesn't allow Benchmarking those machines, they'll sue you if you do. From experience I can tell that his calculation using simple math is about right. Those machines are ridiculously slow when you look at the price. Theres really only two reasons for using those machines.
One is RAS.. which SUN, HP and Nehalem EX can offer as well at a much lower price point and usually with more performance.
Two is when you're using old code. Find someone that'll port your old COBOL Applications to something.. new. When you've found him ask what he wants for doing it. In that case the mainframe really is cheaper and imo thats the only reasons for using those machines.

Sun and HP have been bragging about the poor Performance Mainframes deliver for years - they definitely did so for a reason.
Bragging alone just doesn't help against IBMs sales tactics which are currently being investigated by the FCC and others though.

Reply Parent Score: 1