Linked by Thom Holwerda on Wed 14th Apr 2010 23:51 UTC
IBM This article describes a real-word software port, with examples of how various porting challenges are resolved. If you are a software developer porting software to UNIX, you will find these techniques invaluable in avoiding common pitfalls, resolving bugs, and improving your productivity.
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Kebabbert
Member since:
2007-07-27

foobar,
Oh, of course I meant that "software emulation is 5-10x slower than native code". Thanx for pointing it out.




"You are not accounting for cores/chips/processors correctly. A 64 processor z10 is actually 64 cores. An 8 socket nehalem is 64 cores. If you want per core performance, then it is 3200/64 = 50 emulated mips, and 50 * 5 = 250. So you need 120 nehalem cores by your hoakie numbers."

I didnt get that. Could you explain again? It seems that you claim that 64 Mainframe CPUs have in total: 64 cores? Then it must mean that Mainframe CPUs are single cores. I thought they were quad core?

Who (except IBM) is interested in performance per core? I am comparing one Mainframe cpu vs Nehalem-EX cpu. Not core vs core. I dont claim that Nehalem-EX core is faster than Mainframe core. (This is typical FUD from IBM: shift focus from cpu vs cpu, to something else, such as core vs core.)

Could please explain again, why an Nehalem-EX cpu is slower than a Mainframe CPU? Note that I wrote "CPU" not, core, or ALU, or registers, or whatever. Just because one part of the CPU is faster - it doesnt say anything about the entire cpu. "My car has a better ignition mechanism than your car, therefore my car is faster than yours" - plain FUD. You must compare car vs car, not some small part vs another part. No one is interested in that small part.




"While we're throwing around hoakie numbers, lets account for the other cores in the z10. Not channel cards, but the z10 cores characterized as SAPs and CFs. Since, IBM actually measured that 30,000 MIPs number, we should include the cores doing IO. For the biggest machine, that's another 11 cores. 11 * (30,500/64) = 5200 MIPS. So we can estimate that a z10 is really capable of 35,700 MIPS."

Come on, this is really silly of you. You dont want to do this comparison. You would be really upset if I claimed (just like you do): "Well, the latest Nvidia card is capable of TeraFlops, therefore the Nehalem-EX server must be faster than the Mainframe server".

Now THAT comparison would be hoakie, dont you agree? But it is ok if IBMers do this comparison, right?

BTW, I talked with another IBMer who claimed that: despite you need four POWER6 cpus to match two Intel (ordinary) Nehalem, the POWER6 is faster. Because it has higher clocked core, or something weird. I never understood his logic. It was really weird. Then he started to talk about pricing, the POWER6 software licenses would be cheaper, therefore the POWER6 is faster. I dont get it, where all IBMers find that weird stuff to say? The funny thing is, they BELIEVE it is true! :o) Even today he is convinced that POWER6 is faster than Nehalem. I couldnt talk him out of it. No matter what I said, he refused to listen. :o)

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