Using Power More Efficiently: Dynamic Tuning 2.0

A common thread in modern microprocessor design is being able to use the power budget available. There have been many articles devoted to how to define power budgets, thermal budgets, and what the mysterious ‘TDP’ (thermal design power) actually means in relation to power consumption. Intel broadly uses TDP and power consumption simultaneously, along with a few other values, such as power limits 1 and 2 (PL1 and PL2), which apply to sustained power draw and peak power draw respectively. Most Intel processors up until this point will allow a processor to turbo, up to a peak power draw of PL2 for a fixed time, before enforcing a PL1 sustained power draw. This is all very OEM dependent as well. However, for Ice Lake, this changes a bit.

For Ice Lake, Intel has a new feature called Dynamic Tuning 2.0, which implements a layer of machine learning on top of the standard turbo mode. The idea behind DT2.0 is that the processor can predict the type of workload that is incoming, say transcode, and adjust the power budget intelligently to give a longer turbo experience.

Technically the concepts of PL1 and PL2 don’t magically disappear under this new regime – the processor ends up going below max turbo because the algorithm predicts that the user won’t need it, and this saves up ‘power budget’ in order to enable the turbo to work for longer.

This is a topic that Intel will hopefully go into more detail. We do know that it requires collaboration at the OS level, but how these algorithms are trained would be a useful trove of information. It is unclear whether Intel will allow this feature to be enabled/disabled at the user level, for testing purposes, but it should be noted that unless it is by default ‘on’ for OEM systems, we might end up with some systems enabling it while others do not.

Two Versions of Ice Lake, Two Different Power Targets Thunderbolt 3: Now on the CPU*
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  • name99 - Wednesday, July 31, 2019 - link

    That’s an idiotic chain of reasoning.
    ARM Macs will ship with macOS, not iOS. To believe otherwise only reveals that you know absolutely nothing of how Apple thinks.

    As for comparison, the rough number is A12X gets ~5200 on GB4, Intel best (non-OC’d) gets ~5800. That’s collapsing lots of numbers down to one, but comparing benchmark by benchmark you see Apple does very well (almost matching Intel) across an awful lot.

    If Apple can maintain its past pace (and there is no reason why not...) we can expect A13X to be anywhere from 20% to 35% faster, which puts it well into “fastest [non-OC’d] CPU on earth” territory for most single-threaded use cases. Can they achieve this? Absolutely.
    Just process improvement can get them 10% frequency. I expect A13X to clock around 2.8GHz.
    Then there is LPDDR5 which I expect they will be using, so substantially improved memory bandwidth. Then I expect they'll have SVE (2x256) and accompanying that basically double the bandwidth all the way out from L1 to DRAM.
    These are just the obvious basics. There are a bunch of things they can still do that represent “fairly easy” improvements to get to that 25% or so. (These include more aggressive fusion, a double-pumped ALU, attached ALUs to load/store to allow load-ok and op-store fusion, a micro-op cache, long-term-parking, criticality prediction, ...)

    So, if it’s so easy, why doesn’t Intel also do it? Why indeed? That’s why I occasionally post my alternative rant about how INTC is no longer an engineering company, it is now pretty much purely a finance company...
  • ifThenError - Friday, August 2, 2019 - link

    Sorry, but both these comments seem mighty uninformed. The MacBooks Air and Pro currently and in the foreseeable future all run on Intel CPUs. The Apple Chips A12/13 are used in iPhone, iPad and the likes.

    And regarding your prediction, your enthusiasm seems way over the top. What are you even talking about? Micro-op cache on a RISC processor? Think again. Aren't RISC commands all micro ops already?
  • name99 - Sunday, August 4, 2019 - link

    Strong the Dunning-Kruger is with this one...
    Dude, seriously, learn something about MODERN CPU design, more than just buzz-words from the 80s.
    To get you started, how about you read
    https://www.anandtech.com/show/14384/arm-announces...
    and concentrate on understanding EVERY aspect of what's being added to the CPU and why.
    Note in particular that 1.5K Mop cache...

    More questions to ask yourself:
    - Why was 80s RISC obsessed with REDUCED instructions?
    - Why was ARM (especially ARMv8) NOT obsessed with that? Look at the difference between ARMv8 and, say, RISC-V.
    - Why is op-fusion so important a part of modern high performance CPUs (both x86 and ARM [and presumably RISC-V if they EVER ship a high-performance part, ha...])?
    - which are the fast (shallow logic, even if it's wide) and which are the slow (deep logic) parts of a MODERN pipeline?
  • ifThenError - Monday, August 5, 2019 - link

    Oh my, this is so entertaining you should charge for the reading.

    You demand to go beyond just buzz words (what would be good) while your posts look like entries to a contest on how many marketing phrases can be fit into a paragraph.
    Then you even manage to combine this with highly rude idiom. Plus you name a psychological effect but fail to transfer it to self-reflexion. And as cherry on the top you obviously claim for yourself to understand „EVERY aspect“ of a CPU (an unimaginably complex bit of engineering) but even manage to confuse micro- and macro-op cache and the conceptual differences of these.

    I'm really impressed by your courage. Publicly posting so boldly on such a thin basis is brave.
    Your comments add near zero information but are definately worth the read. Pure comedy gold!

    Please see this as an invitation to reply. I'm looking forwards to some more of your attempts to insult.
  • Techgeek43 - Tuesday, July 30, 2019 - link

    Fantastic article Ian, I for one, cannot wait for ice lake laptops
    Wonderful in-depth analysis, with an interesting insight into the Intel brand
  • repoman27 - Tuesday, July 30, 2019 - link

    "The high-end design with 64 execution units will be called Iris Plus, but there will be a ‘UHD’ version for mid-range and low-end parts, however Intel has not stated how many execution units these parts will have."

    Ah, but they have: Ice Lake-U Iris Plus (48EU, 64EU) 15 W, Ice Lake-U UHD (32EU) 15 W. So their performance comparisons may even be to the 15 W Iris Plus with 64 EUs, rather than the full fat 28 W version.

    I know you have access to the media slide decks, but Intel has also posted product briefs for the general public that contain a lot of this info: https://www.intel.com/content/www/us/en/products/d...

    "On display pipes, Gen11 has access to three 4K pipes split between DP1.4 HBR3 and HDMI 2.0b. There is also support for 2x 5K60 or 1x 4K120 with a 10-bit color depth."

    The three display pipes are not limited to 4K, and are agnostic of transport protocol—each of them can be output via the eDP 1.4b port, one of the 3 DDI interfaces which can support either DisplayPort 1.4 or HDMI 2.0b, or one of the up to 4 Thunderbolt 3 ports. Both HDMI and DP support HDCP 2.2, and DisplayPort also supports DSC 1.1. The maximum single pipe, single port resolution for HDMI is 4K60 10bpc (4:2:2), and for DisplayPort it's 4K120/5K60 10bpc (with DSC).

    Thunderbolt 3 integration for Ice Lake-Y is only up to 3 ports.
  • abufrejoval - Tuesday, July 30, 2019 - link

    What I personally liked most about the GT3e (48 EU) and GT4e (72 EU) Skylake variant SoCs was, that they didn't cost the extra money they should have, especially when you consider that the iGPU part completely dwarfs the CPU cores (which Intel makes you bleed for) and is much better than everything else combined together (have a look at the WikiChips layouts
    https://en.wikichip.org/wiki/intel/microarchitectu...

    Of course, a significantly better graphics performance is never a bad thing, especially when it also doesn't cost extra electrical power: The bigger iGPUs might have actually been more energy efficient than their GT2 brethren at a graphics load that pushed the GT2 towards its frequency limits. And in any case if you don't crunch it on graphics, the idle consumption is near perfect: One of the reasons most laptop dGPU designs won't even bother to run 2D on the dGPU any more but leave that to Intel.

    The biggest downside was that you couldn't buy them outside an Apple laptop or Intel NUC.

    But however much Intel goes into Apple mode (the major customer for these beefier iGPUs) in terms of "x time faster than previous", the result aren't going to turn ultrabooks with this configuration into "THD gaming machines".

    To have a good feel as to where these could go and whether they are worth the wait, just have a look at the Skull Canyon nuc6i7kyk review on this site: That SoC uses 72 EUs and 128MB of eDRAM and should put a pretty firm upper limit to what a 64 EU Ice Lake can do: Most of the games in that review are somewhat dated yet fail to reach 20FPS at THD.

    So if you want to game on the device, you'd be much better of with a dGPU however small and chose the smallest iGPU variant available. No reason to wait, Whisky + Nvidia will do better.

    If you want real gaming performance, you need to put real triple digit Watts and the bandwidth only GDDR5/6 or HBM can deliver to work even at THD, but with remote gaming perhaps it doesn't have to be on your elegant slim ultrabook. There again anything but the GT2 configuration is wasted, because only need the VPU part for decoding Google Stadia (or Steam Remote) streams, which is the same for all configurations.

    For some strange reason, Intel has been selling GT3/4 NUCs at little or no premium over GT2 variants and in that case I have been seriously tempted. And only once I even managed to find a GT3e laptop once for a GT2 price (while the SoC is literally twice as big and the die carrier even adds eDRAM at zero markup), which I stil cherish.

    But if prices are anywhere related to the surface area of the chip (as they are for the server parts), these high powered GTs are something that only Apple users would buy.

    That's another reaons, I (sadly) don't expect them to be sold in anything bug Macs and some NUCs, no ChuWi notebooks or Mini-ITX boards.
  • abufrejoval - Tuesday, July 30, 2019 - link

    ...(need edit)

    Judging from the first 10nm generation, GPUs where the part where obtaining economically feasible yields didn't work out. Unless they have really, really fixed 10nm it's not hard to imagine that Intel could be selling high-count EU SoCs to Apple below cost, to keep them for another generation as flagship customer and perhaps due to long-term contractual obligations.

    But maintaining GT2/3/4 price egality for the rest of the market seems suicidal even if you have a fab lead.

    Not that I expect we'll ever be told: In near monopoly situations the so called market ecnomy becomes surprisingly complex.
  • willis936 - Wednesday, July 31, 2019 - link

    What the hell is a THD in this context?
  • jospoortvliet - Monday, August 5, 2019 - link

    Probably full HD (True HD)?

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