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

-Ofast -fomit-frame-pointer
-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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  • Alistair - Monday, May 17, 2021 - link

    no, that's not right, Tiger Lake is mainly clock speed improvements, not IPC, running Tiger Lake or Comet Lake in a desktop at the same 4.8GHZ all core would get you almost exactly the same performance
  • heickelrrx - Monday, May 17, 2021 - link

    are u drunk?
  • laduran - Tuesday, May 18, 2021 - link

  • mode_13h - Tuesday, May 18, 2021 - link

    > Tiger Lake is mainly clock speed improvements, not IPC, running Tiger Lake or Comet Lake
    > in a desktop at the same 4.8GHZ all core would get you almost exactly the same performance

    You're confusing Comet Lake with Ice Lake. IPC of Tiger Lake isn't much improved above that of Ice Lake.
  • Qasar - Wednesday, May 19, 2021 - link

    can you blame him ? its time intel started using different names for their cpus.
  • mode_13h - Thursday, May 20, 2021 - link

    I didn't mean that in a pointed way. If anything, I thought it would partially validate the statement.

    And yes, I wish Intel would've left the Lakes behind with 14 nm, but I guess there are just too many "lake" names for them to part with it for the mere sake of naming consistency. More annoyingly, they're even using "lake" names for some things that aren't CPUs.
  • Qasar - Thursday, May 20, 2021 - link

    it seems they are staying with lake and cove names so unless you are using a slide ruler and a decoder ring, you have no idea which cpu is what :-) i gave up trying to keep track of their names are which cpu line a while ago.
  • mode_13h - Friday, May 21, 2021 - link

    > it seems they are staying with lake and cove names

    Sapphire Rapids is the next server CPU. Also, the little cores seem to be Monts, while the big cores are Coves.

    I think the biggest groaner is "Lakefield", which is that mobile CPU with one big core, 4 little cores, and a chunk of eDRAM. MS used it in a Surface model.
  • Qasar - Friday, May 21, 2021 - link

    mode_13h, still doesnt change the fact that the names intel gives its cpus, are confusing has he double hockey sticks :-)
  • mode_13h - Sunday, May 23, 2021 - link

    Oh, for sure. It was so nice when *Bridge = LGA 1155, *Well = LGA 1150, and *Lake = LGA 1151.

    ...then, it seemed like nearly everything became a Lake!

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