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In case it helps, the larger context of this story is that IBM has spent a couple billion dollars developing a new server CPU (POWER8) that is just about to come on the market: http://www.forbes.com/sites/alexkonrad/2014/04/23/ibm-debuts...

They've also formed a consortium to promote this processor, of which Google is a flagship member (http://openpowerfoundation.org/). The expectation (or hope, or fear, depending on your point of view) is that Google may be designing their future server infrastructure around this chip. This motherboard is some of the first concrete evidence of this.

The chip is exciting to a lot of people not just because it offer competition to Intel, but because it's the first potentially strong competitor to x86/x64 to appear in the server market for quite a while. By the specs, it's really quite a powerhouse: http://www.extremetech.com/computing/181102-ibm-power8-openp...



I think that rumor also stated something about ARM, so Google may not be done designing its chips yet.

I'm glad they are finally doing this, not so much because I care about what happens in the server world, but because so many product chip decisions at Google have been political (by choosing Intel chips) simply because Otellini was on their board. Hopefully this will signal a change from that.


However, the "Google model" of computation involves a huge amount of cheap "light" servers, instead of a few "big" servers (on which the Power model was based)

Well, the Power architecture had some success in Apple products, but ended with the inability of IBM to scale production and produce parts that consumed less power


Google's servers are not that light, and this is a dual socket one, so 20-32 cores or so, rather than a huge Power 16 socket board which are the real scale up ones, so it is not that much more scale up. You get more IO bandwidth out of Power than Intel.


[citation needed]? I've not seen any useful IO benchmarks of POWER in a long time, if ever, and they've never been remotely comparable to more commodity systems, since POWER almost always gets used in the huge systems you mention...


Citation Given: http://www.extremetech.com/computing/181102-ibm-power8-openp...

Power8 has 230GB/s of bandwidth to ram compared to a Xeon's 85GB/s. That's nearly triple (270.5%) a XEON's I/O speed.


ummm... I see STREAM copy benchmarks for Xeon reporting at least double the number you cite.

Further, a benchmark like this is complicated. How is RAM divided between sockets? What's the bandiwdth between a CPU and memory in another socket? etc etc


Unable to respond, citation not given.

But I'll respond anyways. It looks like you have GB and Gb per second confused. One is 8x the other.

admin-magazine: claims 120Gb/s [1]

intel claims: 246Gb/s [2]

Independent claims on intel forums range from 120-175Gb/s [3]

Intel's cut sheet for their own latest generation xeon states it only supports 25GB/s (200Gb/s) memory bandwidth [4]

[1] http://www.admin-magazine.com/HPC/Articles/Finding-Memory-Bo...

[2] http://www.intel.com/content/www/us/en/benchmarks/server/xeo...

[3] https://software.intel.com/en-us/forums/topic/383121

[4] http://ark.intel.com/products/75465/Intel-Xeon-Processor-E3-...


Reporting memory bandwidth in Gb is misleading.

The page you cite here: http://www.intel.com/content/www/us/en/benchmarks/server/xeo...

shows a triad bandwidth (STREAM) of 246,313.60 MB (megabytes) per second which is 240 GB (gigaBYTES) / sec.

If I'm making a mistake I'm sure we can work it out.


That 240GB is on 4 sockets, so corresponds roughly to the 85GB/socket cited above, while the Power7 compared was about half the Intel, so about 50GB/socket, while Power8 is allegedly at 240GB/socket.


Thanks for the clarification. HN took ~30-40 minutes before it would show a reply option for this post, so I went ahead and acknowledged the performance difference in a reply to my original reply (ugh). Anyway, that's great to see such high memory bandwidth per socket, rather than summed over the whole machine.


If you click the "link" button you can reply sooner...


[4] is not a valid link: the E3 is not the highest performing Intel chip wrt memory. The E3s don't have powerful memory controllers like the E7.


A reply to myself since I can't reply to the informative reply below (thanks HN). The RAM benchmarks for Xeon are per-machine (summed over sockets, presumably with no cross-socket traffic, since cross-socket memory is 1/2 speed) while the Power8 benchmarks are per socket.

That is indeed impressive. no wonder google is considering these. memory bandwidth is indeed critical.


[deleted]


Thanks, but I neither track my score nor care that you think I'm condescending.


The (now-deleted) comment you replied to was right. Your comment would have been much better without "ummm...".

All: please don't use snark in HN comments. It violates civility and degrades the discourse.


It's your opinion that "umm..." is snark. It's what I would say in person if I doubted your claims.

Notice that I actually had a question and it was answered in the thread, which I acknowledged.


Happy to take your word for it.

I could well be hyperallergic after years of wincing at gratuitous unpleasantness in HN comments (edit: and, to be fair, having contributed my own share of it). In person, of course, tone of voice would reveal everything about "ummm...".

Either way, please understand that the intent behind comments like this is in no way personal. The idea is to send feedback signals into the community about the kind of discourse we want to cultivate.


You're microoptimizing. Spending time to complain about an "um" or and "uh" which had no semantic content implied other than what um or uh normally means is pointless. You can't micromanage every conversation, nor should you. Focus on outright negative comments. mine was surprise and disbelief (which was later rectified by data). System working as expect, no SNAFUs!


If it was a snotty 'ummmm', I personally would object to it in real life, too. And I think others would as well. Also, you don't need 'ums' in writing.


Are you talking to yourself?


I think they could use this on edge servers, as well with those algorithms, that they couldn't distribute enough.


I think you are mixing up Power and PowerPC (which was created by IBM, Apple and Motorola in 1991).


What exactly is the difference? Looking at this Wikipedia article, it looks like PPC is the descendant to the Power ISA. https://en.wikipedia.org/wiki/IBM_POWER_Instruction_Set_Arch...

EDIT: Digging a little more gave me the answer: "The POWERn family of processors were developed in the late 1980s and are still in active development nearly 25 years later. In the beginning, they utilized the POWER instruction set architecture (ISA), but that evolved into PowerPC in later generations and then to Power Architecture. Today, only the naming scheme remains the same; modern POWER processors do not use the POWER ISA."

https://en.wikipedia.org/wiki/IBM_POWER_microprocessors


https://upload.wikimedia.org/wikipedia/commons/3/3b/PowerISA...

Gives a nice visual presentation of what happened.




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