Intel’s Turbo Modes

A last minute detail from Intel yesterday was information on the Turbo modes. As expected, not all of the processors actually run at their rated/base frequency: most will apply a series of turbo modes depending on how many cores are registered as ‘active’. Each core can have its frequency adjusted independently, allowing VMs to take advantage of different workload types and not be hamstrung by occupants on other VMs in the same socket. This becomes important when AVX, AVX2 and AVX-512 are being used at the same time.

Most of the turbo modes are a sliding scale, with the peak turbo used when only one or two cores are active, sliding down to a minimum frequency that may be the ‘base’ frequency or just above it. There’s a lot of information for the parts here, so we’ll break it down into stages.

First up, a look at the Platinum 8180 in the different modes:

It should be worth noting what the base frequency actually is, and some of the nuance in Intel’s wording here. The base frequency is the guaranteed frequency of the chip – Intel sells the chip with the base frequencies as the guarantee, such that when the chip is not idle and not in normal conditions (i.e. when not in thermal power states to reduce temperature) should operate at this frequency or above it. Intel also lists the per-core turbo frequencies as ‘Maximum Core Frequencies’ indicating that the processors could be running lower than listed, depending on power distribution and requirements in other areas of the chip (such as the uncore, or memory controller). It’s a vague set of terms but ultimately the frequency is determined on the fly and can be affected by many factors, but Intel guarantees a certain amount and provides guides as to what it expects the turbo frequencies to be.

As for the Platinum 8180, it keeps its top turbo modes while up to two cores are active, and then drops down. It does this again for another two cores, and a further two cores. From this point, under non-AVX load the CPU is pretty much the same frequency until >20 cores are loaded, but does not decrease that much in all.  For AVX 2.0 and AVX-512, the downward slope of more cores means less frequency continues, with AVX-512 taking a bigger jump down at 13 cores loaded. The final turbo frequency for AVX-512 running on all cores is 2.3 GHz.

Comparing the two 28-core CPUs for which we have turbo information gives this graph. The numbers relate to the number of cores need to be loaded for that frequency.

Both processors are equal to each other for dual core loading, but the separation occurs when more cores are loaded. As we move through to AVX 2.0 and AVX-512, it is clear where the separations are in performance – to get the best for variable core loading, the more expensive processors are required.

Here’s the big table for all the processors on Non-AVX loading:

Despite the 2.0/2.1 GHz base on most of the Platinum series, all the CPUs will turbo up to 3.7-3.8 GHz on low core loading except for the lower power Platinum 8153. For users wanting to strike a good balance between the core count and frequency, the Gold 6154 is probably the place to be: 18 cores that will only ever run at 3.7 GHz with non-AVX loading (3.5-2.7 GHz on AVX-512 depending on core count), and will be $3543 as a list price at 205W. It is perhaps worth noting that this will likely top any of the Core i9 processors planned: at 18-cores and 205W for 3.7 GHz, the Core i9-7980XE which will have 18 cores but run 165W will likely be clocked lower (but also only ~$2000).

Moving onto AVX2.0 and AVX-512:

Xeon Skylake-SP SKUs Intel Expanding the Chipset: 10 GigE & QuickAssist
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  • Kaotika - Tuesday, July 11, 2017 - link

    http://www.anandtech.com/show/11464/intel-announce...
    This one remains wrong though
    Reply
  • Ian Cutress - Tuesday, July 11, 2017 - link

    Always reference the newest piece, especially the main review.
    Or we'd spend half of our time going back and updating old pieces and reviews with new data.
    Reply
  • scottb9239 - Tuesday, July 11, 2017 - link

    On the POV-RAY benchmark, shouldn't that read as almost 16% faster than the dual 2699 v4 and 32% faster than the dual 8176? Reply
  • scienceomatica - Tuesday, July 11, 2017 - link

    I think that a fair game would be to compare the top offer of one and the other manufacturer, in other words, the Xeon 8180 should be included in the benchmark regardless of the aspect of the price. Then the difference would be quite in favor of the Intel processor, although it has few cores less. Reply
  • Tamz_msc - Tuesday, July 11, 2017 - link

    Will we get to see more FP HPC-oriented workloads like SPECfp2006 or even 2017 being discussed in a future article? Reply
  • lefty2 - Tuesday, July 11, 2017 - link

    I can summarize this article: "$8719 chip beaten by $4200 chip in everything except database and Appache spark."
    Well done Intel, another Walletripper!
    Reply
  • Shankar1962 - Wednesday, July 12, 2017 - link

    Then why did google att aws etc upgraded to skylake. They could have saved billions of dollars. Reply
  • Shankar1962 - Wednesday, July 12, 2017 - link

    Look at what big players upgrading to skylake reported
    These are real workloads
    No one cares about labs
    These numbers decide who wins and who loses
    No wonder AMD sells at $4200

    https://www.google.com/amp/s/seekingalpha.com/amp/...
    Reply
  • nitrobg - Tuesday, July 11, 2017 - link

    Pricing on page 10 should reflect that the 2P EPYC prices are for 2 processors, not per CPU. The price of Xeons is per CPU. Reply
  • coder543 - Tuesday, July 11, 2017 - link

    That doesn't seem true. The prices they currently have seem to be correct. Got a source? Reply

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