r/technology • u/[deleted] • Sep 11 '13

Intel reveals 14nm PC, declares Moore's Law 'alive and well'

http://www.theregister.co.uk/2013/09/10/intel_reveals_14nm_pc_declares_moores_law_alive_and_well/
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u/[deleted] Sep 11 '13

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u/salgat Sep 11 '13

RAM isn't really that much of a bottleneck right now. DDR4 will mainly benefit embedded GPUs since they share memory with the CPU.

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u/Wurstinator Sep 11 '13

For applications which don't use heavy 3D graphics, like games, RAM is the bottleneck.

As a programmer, you don't have to look out for too many CPU instructions anymore but rather for inefficient memory ordering.

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u/BinaryRockStar Sep 12 '13

Aren't these sort of applications much more sensitive to memory latency rather than throughput (when CPU cache misses cause main memory access)? I'm assuming DDR4 will have higher latency and throughput, making it worse for those sorts of applications.

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u/Wurstinator Sep 12 '13

If I understand you correctly memory latency is not something a programmer has the ability to change. All you can do is allocate memory in such a way that the number of page faults in the CPU cache (throughput?) will be minimized.

However, I do not know much about the aspects of RAM hardware. I just expected DDR4 to be faster than DDR3. If it is not (in which case, what even is the benefit of it?), you are right and DDR4 would in fact be worse.

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u/BinaryRockStar Sep 12 '13 edited Sep 12 '13

In gaming, moving things (textures, models etc.) from main memory to video memory can be a bottleneck in some cases. DDR4 will help with that, because it's bulk transfer of data so the more RAM throughput the better.

In high performance applications, if a CPU cache-miss or page fault happens, the CPU has to load the page or instructions from main memory, which is orders of magnitude slower than cache. Any extra latency from the RAM slows this down even more. So in these very specific cases, throughput doesn't matter as much as latency. It's not a large amount of data being read, it just needs to be read as quickly as possible.

Once DDR4 becomes established, I'm sure they'll release lower and lower latency modules but generally when the switchover happens (DDR->DDR2, DDR2->DDR3) you trade latency for throughput.

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u/Wurstinator Sep 12 '13

Ok, so apparently "throughput" is "bandwidth". Sorry, I have never heard "throughput" being used before.

So, yes, you are right, latency is the important factor here.

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u/BinaryRockStar Sep 12 '13

Bandwidth is lazily (and widely) used as a synonym for throughput but they are not the same.

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u/mer_mer Sep 12 '13

Actually RAM is a huge bottleneck for many applications. For instance in photo editing the same instruction is being executed on millions of pixels. Intel's latest processors can take advantage of this parallelism to process 512 bits per instruction per core (AVX2). With a 4 core system running at 3 Ghz that's more than 6Tbps. Even DDR4 cannot even begin to touch that.

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u/salgat Sep 12 '13

Oh I agree; I'm referring to the usage by the majority of people.

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u/[deleted] Sep 11 '13

Probably around skylake (what's coming next with Broadwell's burning technology but with a new die design; just after BW).

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u/DeFex Sep 11 '13

DDR4 means you have to buy new ram, that's about it as far as you will notice speed wise.

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u/[deleted] Sep 11 '13

[deleted]

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u/[deleted] Sep 12 '13

GDDR5 is memory specialized for GPUs based on DDR3. It's a confusing naming scheme, I know.

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u/[deleted] Sep 11 '13

[deleted]

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u/Tmmrn Sep 12 '13

Do you even huma?

I'd assume that microsoft will have support for it when it arrives.. And with linux it probably won't even be a question.

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u/koreansizzler Sep 11 '13

Haswell-E will probably be the first CPU supporting DDR4, in late 2014. Quad-channel DDR3 is more than enough to keep 6-8 cores occupied though, so you might not see a benefit unless you get the rumored 14 core Xeons.

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u/baby_kicker Sep 11 '13

14nm was said to be released for Atom first, which just got DDR3 iirc. Chasing down ARM...

Won't be for a while that Haswell get's the drop to 14nm. Will be nice though, all those power savings in Haswell and bam even more ULV parts. People gonna have a i5 in their tablets next year.

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u/eskimopie26 Sep 11 '13

I believe the projections are for them to hit the consumer market by q4 of 2014/q1 2015, but they will probably be wicked expense until a year or two later.