SPEC CPU - Single-Threaded Performance

SPEC2017 and SPEC2006 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.

We run the tests in a harness built through Windows Subsystem for Linux, developed by our own Andrei Frumusanu. WSL has some odd quirks, with one test not running due to a WSL fixed stack size, but for like-for-like testing is good enough. SPEC2006 is deprecated in favor of 2017, but remains an interesting comparison point in our data. Because our scores aren’t official submissions, as per SPEC guidelines we have to declare them as internal estimates from our part.

For compilers, we use LLVM both for C/C++ and Fortan 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.

To note, the requirements for the SPEC licence state that any benchmark results from SPEC have to be labelled ‘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.

Single-threaded performance of TGL-H shouldn’t be drastically different from that of TGL-U, however there’s a few factors which can come into play and affect the results: The i9-11980HK TGL-H system has a 200MHz higher boost frequency compared to the i7-1185G7, and a single core now has access to up to 24MB of L3 instead of just 12MB.

SPECint2017 Rate-1 Estimated Scores

In SPECint2017, the one results which stands out the most if 502.gcc_r where the TGL-H processor lands in at +16% ahead of TGL-U, undoubtedly due to the increased L3 size of the new chip.

Generally speaking, the new TGL-H chip outperforms its brethren and AMD competitors in almost all tests.

SPECfp2017 Rate-1 Estimated Scores

In the SPECfp2017 suite, we also see general small improvements across the board. The 549.fotonik3d_r test sees a regression which is a bit odd, but I think is related to the LPDDR4 vs DDR4 discrepancy in the systems which I’ll get back to in the next page where we’ll see more multi-threaded results related to this.

SPEC2017 Rate-1 Estimated Total

From an overall single-threaded performance standpoint, the TGL-H i9-11980HK adds in around +3.5-7% on top of what we saw on the i7-1185G7, which lands it amongst the best performing systems – not only amongst laptop CPUs, but all CPUs. The performance lead against AMD’s strongest mobile CPU, the 5980HS is even a little higher than against the i7-1185G7, but loses out against AMD’s best desktop CPU, and of course Apple M1 CPU and SoC used in the latest Macbooks. This latter comparison is apples-to-apples in terms of compiler settings, and is impressive given it does it at around 1/3rd of the package power under single-threaded scenarios.

CPU Tests: Core-to-Core and Cache Latency SPEC CPU - Multi-Threaded Performance
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  • Ppietra - Monday, May 17, 2021 - link

    The M1 Mac mini peak power makes no sense in that graph!
    You are comparing the Mac mini Total Power Draw on the Wall, with other devices’ CPU peak power - clearly completely different things.
  • Andrei Frumusanu - Monday, May 17, 2021 - link

    I think that was a leftover from Ian or a misunderstanding, the M1 does have around 32W peak package power, but you're right, CPU only is only around 21W, I've edited that.
  • Ppietra - Monday, May 17, 2021 - link

    ok! I understand, I think it was the data from the original article where you weren’t able to measure CPU power. The value makes more sense now.
  • yankeeDDL - Monday, May 17, 2021 - link

    This is not surprising, and it is in line with the TL-U results.
    I think TL-U is a compelling option, but given the possibility, I'd go for an AMD-based laptop: 30 more minutes of battery life are well worth 7-10% single-core performance disadvantage, all the rest considered. IMHO.
  • tipoo - Monday, May 17, 2021 - link

    Moar 👏Watts 👏

    Feels like all Intel has now
  • jagoanjoko - Monday, May 17, 2021 - link

    Damn I still expect a little bit better (or much better) result from H45. Many Core i7 10870H can reach 1.600+ points on Cinebench R15 MT. We suppose to wait for final product. But still too disappointing :(

    Fortunately intel will trading blow with AMD today and for the rest of 2021. Intel can't be strong enough to compete with AMD if they haven't TGL-H45 series
  • Yojimbo - Monday, May 17, 2021 - link

    Isn't the unplugged, battery-only behavior the power usage that matters for a laptop?
  • jagoanjoko - Monday, May 17, 2021 - link

    I think it's matter for ultrabook and any ultra portable laptops

    And become less relevant for thicker laptops

    But it's nice to have decent battery life on your thicker laptops so you don't have to bring those heavy charging bricks all times.
  • mode_13h - Monday, May 17, 2021 - link

    Ask people who run demanding games or run heavy workloads on their laptops (who are precisely the market for this thing) and you'll probably find they spend most of their time plugged in.
  • Yojimbo - Monday, May 17, 2021 - link

    I myself have a desktop replacement laptop that I use almost exclusively plugged in. When it's plugged in I certainly care about noise, but I don't care about power usage. However I do sometimes use it on battery power, both on power hungry tasks (with which I try to have it plugged in when running) and less power-hungry tasks. That's when battery life, and hence power draw, becomes important to me for the laptop.

    So, although I use my laptop mostly plugged in and I do care about power draw, the power draw I care about is almost entirely for when the laptop is unplugged. And of course I also care about the performance I get for that power draw in those situations. The noise factor must be considered exclusively laptop to laptop, so looking at power draw in plugged in situations isn't very useful. And frankly, I can't see a good reason that many consumers to be looking at the situation differently and would be concerned about the power draw of the laptop when plugged in.

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