CPU Tests: SPEC Performance

SPEC2017 is a series of standardized tests used to probe the overall performance between different systems, different architectures, different microarchitectures, and setups. The code has to be compiled, and then the results can be submitted to an online database for comparison. It covers a range of integer and floating point workloads, and can be very optimized for each CPU, so it is important to check how the benchmarks are being compiled and run.

For compilers, we use LLVM both for C/C++ and Fortran tests, and for Fortran we’re using the Flang compiler. The rationale of using LLVM over GCC is better cross-platform comparisons to platforms that have only have LLVM support and future articles where we’ll investigate this aspect more. We’re not considering closed-sourced compilers such as MSVC or ICC.

clang version 10.0.0
clang version 7.0.1 (ssh://git@github.com/flang-compiler/flang-driver.git
 24bd54da5c41af04838bbe7b68f830840d47fc03)

-Ofast -fomit-frame-pointer
-march=x86-64
-mtune=core-avx2
-mfma -mavx -mavx2

Our compiler flags are straightforward, with basic –Ofast and relevant ISA switches to allow for AVX2 instructions. We decided to build our SPEC binaries on AVX2, which puts a limit on Haswell as how old we can go before the testing will fall over. This also means we don’t have AVX512 binaries, primarily because in order to get the best performance, the AVX-512 intrinsic should be packed by a proper expert, as with our AVX-512 benchmark. All of the major vendors, AMD, Intel, and Arm, all support the way in which we are testing SPEC.

To note, the requirements for the SPEC licence state that any benchmark results from SPEC have to be labeled ‘estimated’ until they are verified on the SPEC website as a meaningful representation of the expected performance. This is most often done by the big companies and OEMs to showcase performance to customers, however is quite over the top for what we do as reviewers.

SPEC2017 Rate-1 Estimated Total

In the single threaded test, the jump over the regular Zen 3 Ryzen mobile variant (5980HS) at the same power is quite substantial: +9.6% on integer performance and +14.1% on floating point. The move from DDR4 to DDR5 is quite substantial in that regard, and it’s seen in a lot of our upcoming benchmarks.

We didn’t see any change from 35 W to 45 W to 65 W in our AMD testing as the power consumption of the chip in single threaded workloads did not exceed 24 W, however we did see performance difference in Intel’s Alder Lake going from 45 W to 65 W, showcasing how much power the core can consume.

But if we compared that to Intel’s latest Alder Lake offerings, there’s a deficit in both categories – even though our lowest data here is at 45 W, we can see that the 45 W testing of the previous generation Intel also beats the 6900HS at SPECint (but AMD wins in SPECfp). This is something that carries through to multi-threaded performance.

SPEC2017 Rate-N Estimated Total

For Multi-Threaded performance, we only saw the slightest improvement from AMD moving up to 65 W, perhaps showcasing that the hardware is limited in other ways than just power and the uplift from DDR4 to DDR5. In any event, at 35 W, AMD still surpasses what the previous generation Intel i9-11980HK can provide at 65 W.

But if we compare it to Intel’s latest Alder Lake processors, featuring 6 performance cores and 8 efficiency cores, we now have 20 threads up against AMD’s 16 threads. If we compare 45 W to 45 W, Intel has a +14.0% lead in integer and a +13.3% lead in floating point, despite the 20% increase in threads. With Intel introducing this dual tier performance with hybrid SoCs, multi-threaded performance is going to be a combination of fast+slow and it all comes down to how the system can divide up the work.

Performance Per Watt CPU Tests: Office and Science
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  • yankeeDDL - Tuesday, March 1, 2022 - link

    Great article, as usual.
    It seems clear that Intel's AL still has the performance advantage, however, in the Conclusion page, the performance comparison is reference to the nominal consumption (35W, 45W, 65W), while we know that Intel's part can reach twice as much power, in practice, making an apples-to-apples comparison quite difficult, especially in light of Intel's better scaling with more Power.

    Is there a way to check the exact performance per core under the same exact consumption (or scaled)?
    I am especially interested as a user of the 1165G, which is an absolute battery eater (and/or heater): it seems that AL is a huge improvement, but if it also draws 100W (instead of 45W) to beat Ryzen by a 10%, then it's not worth it. In my opinion.
    Reply
  • Spunjji - Tuesday, March 1, 2022 - link

    Yes, the overall picture that has built up is of Intel's Alder Lake winning out at higher power levels (40W+) while AMD coming out ahead below that.

    This is good, because it means that we have great options for people who want the best possible performance in a mobile form-factor and for people who want a more even balance of performance and power usage. It's a nicer situation to be in than when Intel complete owned the mobile segment, followed by the years of stagnation at 14nm.
    Reply
  • yankeeDDL - Tuesday, March 1, 2022 - link

    Agree on all points.
    Intel's Tiger Lake is an absolute disaster, and it is actually surprising that Intel only managed to lose 50% market share with such a lousy product compared to Ryzen.
    And equally surprising is the insane jump in performance and perf/watt achieved with AL. Definitely good for the consumers.
    Reply
  • mode_13h - Tuesday, March 1, 2022 - link

    > Intel's Tiger Lake is an absolute disaster

    That seems like an overstatement. It just didn't improve enough against Ryzen, particularly in light of the 5000-series' gains. However, especially in light of Ice Lake's disappointments, Tiger Lake didn't seem so bad.
    Reply
  • Alistair - Tuesday, March 1, 2022 - link

    Tiger Lake was a stroke of luck for Intel, their worst product ever during a massive silicon shortage. They spent the year selling quad cores because AMD was selling everything they could make, not because Tiger Lake was any good. Reply
  • bigboxes - Wednesday, March 2, 2022 - link

    For sure. I went with AMD for the first time since 2006 this last year. Reply
  • Samus - Thursday, March 3, 2022 - link

    The irony here is AMD mobile CPU's are widespread in lots of desktops and AIO's, even high end units. You would rarely, if ever, see Intel U-series parts in desktops\AIO's outside of USFF's or low-end AIO's with Celeron\Pentiums.

    This is happening partially because AMD doesn't have a wide product stack like Intel. And they don't need too. The AMD U-series parts are absolute performance monsters and have been for the last 3 generations.
    Reply
  • abufrejoval - Friday, March 4, 2022 - link

    I own both, a Ryzen 5800U in a notebook and an i7-1165G7 as a NUC.

    They are really quite comparable, both in iGPU performance, in scalar CPU power and even in multi-threaded CPU power.

    At 15 Watts the 8 Ryzen cores operate below the CMOS knee, which means they have to clock so low they can't really gain much against 4 Tiger Lake cores clocking above it. Synthetic benchmarks may prove a lead that's next to impossible to realize or really relevant in day-to-day work. For the heavy lifting, I use a 5950X, which isn't that much faster on scalar loads, but runs almost as many rings around the 5800U as the i7-1165G7: the extra Watts make more of a difference than the cores alone.

    My impression is that the Ryzen needs the higher power envelope, 35 or even 65 Watts, and of course a matching workload to put those extra cores to work. AMD's primary aim for their APUs was to cover as many use cases as possible from a single part and they do amazingly well. If they could afford to do a native 4 core variant as well, I'm pretty sure that would outsell the 8 core.

    In fact the SteamDeck SoC would probably make a better notebook part for many (not everyone).

    And there is nothing wrong with Tiger Lake, except that perhaps today there are better SoCs around: it was and remains a welcome improvement over the previous generations from Intel.

    Buy it used and/or cheaper than these AL parts and you should have little to complain about... unless complaining is what you really enjoy.
    Reply
  • mode_13h - Tuesday, March 1, 2022 - link

    > Great article, as usual.

    I thought so, as well, which was a relief. Then, I noticed the by-line:

    "by Dr. Ian Cutress"
    Reply
  • lemurbutton - Tuesday, March 1, 2022 - link

    People shouldn't care that much about AMD and Intel on laptops right now. M1 series completely destroys both. AMD and Intel are 3-4 years behind. Reply

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