moinmoin
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- Jun 1, 2017
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For the market that Sierra Forest and Bergamo will be competing in, nothing right now. Though obviously Intel has a few networking chips that I suppose could count.
For a comparison point, best to look at the ARM vendors, because they're realistically why these small core solutions exist in the first place. Graviton has been a pretty big driver for Amazon, even if they're still majority x86.
Did amazon release any white papers on their in house processor design? does anyone know what comes after granite rapids for w class xeons?
I would assume the small batch inferencing that you'd want a CPU for have a significant affinity with higher perf/thread (i.e. the big cores). And certainly the smaller cache sizes would hurt a lot, given how memory bandwidth intensive most heavy AVX use cases are.
I'm not going to say that a niche for strong vector compute on the small cores doesn't exist, but all in all, it doesn't seem like the ideal tradeoff for how AMD or Intel are positioning their small core offerings.
Unless Intel botches everything (likely), Meteor Lake appears to be targeting efficient, low power designs. No 5.5ghz to be found. The evidence I’ve seen indicates these chips will be in premium ultrabooks and such. Think 14 cores (6+8) with a 10-20 hour battery life in a sub 2lb laptop.
One need only look at Intel’s launch cadence to know Arrow Lake is launching Q4.
The Zen 4 cloud cores people here keep claiming will magically appear in desktop/mobile chips. 🤣
Don't confuse Netburst double interger alu clock here. Pentium4 also double pumped both integer and fpu instructions - Willamette/Northwood P4 had only 16 bit integer alu and 64 bit FPU alu. Both 32 bit integer and 128bit SSE instructions are executed double pumping instruction twice in execution units, just like what AMD is doing with Zen4.
That's not fully right. Splitting instruction is needed when cpu has for example only 64 bit registers and need to execute instruction which uses 128 bit registers. When cpu has registers that match instruction register length there's no need to split anything. If execution ALU's are not as wide as register instruction is just looped through alu as many times that whole instruction is executed. There's plenty of cpu designs that use that approach . But AVX512 has huge number of physical registers - taking existing design and just increasing fpu register file to AVX512 isn't area-efficient - AMD solve that problem by redesigning their FPU to use single centrally located register file instead of private register files per FPU as previous Zen designs did. And by doing that AMD's fpu take big step towards Intel big core designs - if they want to expand their FPU to use 512 bit execution pipelines that isn't huge step anymore. But it pretty much looks that they got better implementation by staying with 256 bit execution and 256 bit load/store engine.
That was more of a marketing wizard than anything else, since the pipeline is already working at max frequency there s no way that there s a part that would "pump" the frequency by a 2 factor.
The term relate to a staggered ALU, actually 2 ALUs, that can execute two independant ops in one cycle, at this rate FMA is also double pumped.
Was there a P4 model with double-pumped 64-bit operations?
I recall that one of the interesting features of the initial P4 micro-architecture was it's double-pumped ALU. I think Intel called it something like the Rapid Execution Unit, but basically it mean...
And about the topic some info from Computerbase if this wasnt already posted :
Intel Emerald Rapids: Analyse weist auf viel größeren L3-Cache hin
Semi Analysis hat eine umfassende Analyse zur Ausstattung der kommenden Server-CPU-Familie Intel Emerald Rapids erstellt.
Actually as both of those ALU's need only half of clock cycle two of them can be driven sequentially in one clock cycle. So alu 1 calculates something and alu2 uses that calculated value in it's inputs in same clock cycle, there can be dependence unlike with case with two parallel alus. Willamette/NW P4's had 0.5 clock cycle alu latency for simple operations. And it also used that double clocking in AGU's and calculated first 16 bits of address in same clock cycle where it was used.
There s 2 ALUs for one port, this amount to double the throughput per clock cycle if the ops are not dependent.
It's also mentioned in that link you pasted, Willamette/NW can do 2 simple alu operations in single clock cycle even if they are dependent. Prescott did lose that double clocking scheme.
Methink that it s not pure dependency, if the dependency is chained, that is, the result of one computation is needed to compute the following op then there s no way that it could be executed in a single cycle.
Your picture is quoted from there where it's explained too.
They say that 3 half cycles are required (3 fast clock cycles), 1 op per half cycle (so 2 half cycles for 2 ops) plus one half cycle to process the ALU flag, so 1.5 cycle to have a usable data output, indeed they state that throughput is not doubled but just significantly improved.
Notice that each ALU process at a 16 bit width, so 1 cycle is necessary to process on a 32 bit width, plus said 0.5 cycle to process the ALU flag.
It's about dependencies - not total execution time. When lower 16 bits of alu operation is completed it can forwarded to next dependent alu operation within same clock cycle so dependency latency drops to half - two dependent alu operations per clock cycle can calculated throughput wise. It's well explained in that Intel document in part low latency integer alu.
And related to Zen4 - if you read that Pentium4 Intel document you can find Intel describes how their FPU uses 128 bit registers and ports but uses 64 bit arithmetic hardware which completes full 128 bit SSE-operations in two clock cycles. It's absolutely same approach that AMD uses for their Zen4 but with 512 bit registers and execution ports with 256 bit arithmetic units.
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I understand the concept, but overall it doesnt bring that much better throughput even if it can cope with dependencies, they are still bound by latencies, among others of L/S unit.
I dont know exactly AMD s all approaches, but operands are indeed 64 bits whatever the width, 128b is just 2 x 64b in a row.
Wether to put enough arithmetic units to execute everything in a cycle or to re use fewer ones and execute the ops in several passes is a up to the designers choice, it can be efficient enough for mixed code, guess that AMD use this approach to save some complexity, and the inherent power and added silicon, so far this seems to work well for AVX512 comparatively to larger units for Intel, at least on a perf/watt point of view.
uzzi38
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- Oct 16, 2019
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SteinFG
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There's already a thread for phoenix
Question - AMD Phoenix/Zen 4 APU Speculation and Discussion
I can finally make this thread. Phoenix is indeed RDNA3. My advice to everyone: treat the old APU rumours as being out of date.
forums.anandtech.com
Hulk
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- Oct 9, 1999
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Intel to Show Off E-Core-Based CPU with Backside Power Delivery
A chip that will never be mass produced will show the benefits of a crucial technology.
Intel 4 could bring more.
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