PeakDash

SPEC2017 Single-Threaded Results

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.

We run the tests in a harness built through Windows Subsystem for Linux, developed by 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 it is good enough. Because our scores aren’t official submissions, as per SPEC guidelines we have to declare them as internal estimates on 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-source 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.

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.

Opening up our performance analysis of the Ryzen Threadripper 7980X in SPEC2017 1T, as we typically do, we split the results between SPECint2017 and SPECfp2017. Starting with SPECint2017, we can see clear gains in the Ryzen Threadripper 7980X (Zen 4) compared to the previous Threadripper 3990X processor (Zen 2). Given the generational gap between the two core architectures, AMD never released regular HEDT-focused Zen 3 Threadripper processors.

In the majority of our tests, we're seeing single-threaded performance gains of between 65 and 93% within the 500.perlbench_r test of the SPECint2017 1T suite provided the largest gain in ST performance we saw. Looking at how the Intel Xeon W9-3495X performed in SPECint2017, lower single-threaded performance is expected due to the slower core frequencies, and our data shows this. It still puts it ahead of the Ryzen Threadripper 3990X in each scenario, but the Ryzen Threadripper 7980X performs best of all.

Focusing on the second half of our SPEC2017 1T suite, the SPECfp2017 section, we can see that although the performance gap between the Threadripper 7980X isn't as big as SPECint2017 1T, it still represents solid generational gains over the 3990X. The SPECfp2017 1T section of the suite also puts the Intel Xeon W9-3495X closer to the older Threadripper 3990X, which can, again, be explained due to the much slower core frequencies, e.g., 1.9 G base, 3.4 G turbo vs. 2.9 G base, 4.3 G turbo.

Overall, in SPEC2017 1T, the AMD Ryzen Threadripper 7000 represents significant single-threaded gains over the Threadripper 3990X, but we expected this given the generational jump between the two processors.

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