Software Archives
An Early Look At The AMD P-State CPPC Driver Performance vs. ACPI CPUFreq

Earlier this month AMD posted their initial public patches for the AMD P-State CPU frequency scaling driver that leverages ACPI CPPC for ultimately aiming to provide better power efficiency and more responsive CPU frequency scaling / performance state decisions on Zen 3 (and Zen 2 eventually) processors. This is part of the effort around AMD and Valve collaborating for better Linux efficiency especially with the AMD-powered Steam Deck.

22 September 2021 - 17 Comments
Running Linux 5.15-rc1 Causing A New Slowdown... Here's A Look

As usual when the Linux 5.15 merge window began wrapping up, I set out to dive into its performance to see what is in store for this next version of the kernel and whether there was any regressions or other performance changes worth noting. Linux 5.15 overall has been in good shape for the "-rc1" state except noticing that code compilation workloads were taking longer on multiple Linux 5.15-rc1-running systems than Linux 5.14 or prior. Seeing it across multiple systems and a very real-world regression, it was worth bisecting and looking closer so here are the details.

16 September 2021 - 27 Comments
Benchmarking The Performance Impact Of Linux 5.15's Newest Protection Around Side Channel Attacks

With the in-development Linux 5.15 kernel there is a new option for further protecting the kernel around side channel attacks and information leakage. Enabling the option will ensure that any caller-used register contents are zeroed prior to returning from a function. While the reported performance cost is said to be small, I decided to run some benchmarks when toggling this new Kconfig hardening option.

3 September 2021 - 13 Comments
GCC 11 PGO With The AMD Ryzen 9 5950X For Faster Performance

It's been a while since last running benchmarks evaluating the performance of GCC's profile guided optimizations (PGO) for helping to optimize the performance. But stemming from the discussions around PGO'ing the Linux kernel (though that effort is stalled for now), several Phoronix readers inquired about seeing some fresh PGO figures with GCC 11. So here are such benchmarks of GCC 11 with the upcoming Ubuntu 21.10 running on an AMD Ryzen 9 5950X desktop.

31 August 2021 - 13 Comments
LLVM Clang 13 Performance Is In Great Shape For Intel Xeon "Ice Lake"

Earlier this month was a look at the LLVM Clang 13 performance on EPYC 7003 showing this forthcoming compiler update to be in good shape for AMD Zen 3, but how is the performance looking on the Intel side? This round of benchmarking is looking at the LLVM Clang 11 / 12 / 13 compiler performance on Intel's flagship Xeon Platinum 8380 "Ice Lake" 2P server configuration.

26 August 2021 - 5 Comments
An Early Look At LLVM Clang 13 Performance On AMD Zen 3

With LLVM/Clang 13 feature development having ended last week and the 13.0 release candidate being tagged, in starting off the benchmarking cycle first up I was looking at how well this new compiler is performing compared to LLVM Clang 12 stable on an AMD EPYC 7543 (Zen 3) Linux server.

12 August 2021 - 7 Comments
AOCC 3.1 Compiler Performance Against Clang 12, GCC 11 On AMD EPYC

Following the recent benchmarks seeing how AMD's new AOCC 3.1 compiler has brought some performance improvements over the prior AOCC 3.0 release that introduced initial Zen 3 optimizations, here are some benchmarks looking at how that latest AMD Optimizing C/C++ Compiler performance compares to the upstream LLVM Clang 12 compiler for which it is based as well as against GCC 11 as the latest GNU compiler release that remains common to Linux systems.

29 July 2021 - 4 Comments
AMD AOCC 3.1 Compiler Performance On EPYC 7003 / Zen 3

Last week AMD released their AOCC 3.1 compiler that is their downstream of LLVM Clang/Flang and carrying various yet-to-be-upstreamed patches for benefiting their latest processors. While just a point release, curiosity got the best of me for firing up benchmarks of this latest AMD Optimizing C/C++ Compiler release.

27 July 2021 - 1 Comment
Squeezing More Performance Out Of The Linux Kernel With Clang + LTO

With the Linux 5.12 kernel bringing support for building the kernel with link-time optimizations (LTO) when using the LLVM Clang compiler, here are some benchmarks looking at that performance impact as well as more generally seeing how the LLVM Clang compiler performance is looking when building the Linux kernel relative to GCC.

21 July 2021 - 40 Comments
GCC 8 Through GCC 11 Stable Plus GCC 12 Compiler Benchmarks

For today's benchmarking is a look at how the GNU Compiler Collection has performed over the past few years going from the GCC 8 stable series introduced in 2018 through the recently released GCC 11.1 stable feature release plus also including the current early development snapshot of GCC 12.

8 July 2021 - 12 Comments
LLVM Clang 12 Benchmarks At Varying Optimization Levels, LTO

Earlier this month were benchmarks looking at GCC 11 performance with varying optimization levels and features like link-time optimizations. Stemming from reader requests, here are now similar reference benchmarks off LLVM Clang 12.0 on the same system with going from -O0 to -Ofast and toggling -march=native and LTO usage.

25 June 2021 - 18 Comments
GCC 11 Compiler Performance Benchmarks With Various Optimization Levels, LTO

Given the recent forum discussion stemming from the -O3 optimization level still too unsafe for the Linux kernel (in part due to older, buggy compilers) and some users wondering about the current -O2 versus -O3 compiler optimization level impact, here is a fresh round of reference benchmarks using GCC 11.1 on Fedora Workstation 33 looking at various optimization levels and optimizations tested on dozens of different application benchmarks to see the overall impact on performance.

14 June 2021 - 49 Comments
Intel Xeon Platinum 8380 P-State CPU Frequency Scaling Comparison

As part of the curiosity-driven benchmarks and areas of technical interest now that we've gotten some of our initial Intel Xeon Platinum 8380 "Ice Lake" benchmarks out of the way has been looking into the performance of Linux's P-State CPU frequency scaling driver on the 3rd Gen Xeon Scalable server. Benchmarked for the latesting testing was the power/efficiency out-of-the-box with P-State powersave as used by default with many Linux distributions against the P-State "performance" mode as well as putting P-State into passive mode to be able to via intel_cpufreq to try the Schedutil governor that relies on the kernel's scheduler utilization data for making frequency scaling decisions. Here is a number of power/performance governor benchmarks with the dual Xeon Platinum 8380 server in these varying kernel configurations.

7 June 2021 - 6 Comments
LLVM Clang 12 Leading Over GCC 11 Compiler Performance On Intel Xeon Scalable Ice Lake

Recently we have been running a number of compiler benchmarks looking at the recently released LLVM Clang 12 and GCC 11 open-source code compilers. There is as healthy and competitive competition as ever between GCC and Clang with the mainline Linux kernel these days working well under Clang, more software projects shifting to Clang by default, and the performance being as tight as ever between GCC and Clang for compiled C/C++ code on x86_64 and AArch64. In today's article are benchmarks of Clang 12 vs. GCC 11 on the dual Intel Xeon Platinum 8380 Ice Lake server.

4 June 2021 - 17 Comments
LLVM Clang 12 Compiler Is Performing Very Well For AMD Ryzen 9 5950X / Zen 3

Earlier this week I posted some benchmarks looking at the compiler performance of GCC 11 vs. LLVM Clang 12 on the Intel Core i9 11900K "Rocket Lake" processor while in this article the same tests and same software are being carried out on an AMD Ryzen 9 5950X "Zen 3" desktop. With these AMD Linux tests the Clang 12 compiler not only yielded the fastest binaries at -O2 but carried through in the more optimized configurations as well.

20 May 2021 - 4 Comments
GCC 11 vs. LLVM Clang 12 Performance On The Intel Core i9 11900K Is A Heated Race

For those wondering how GCC and LLVM Clang are competing when running on Intel's latest Rocket Lake processors, here are some GCC 11 vs. LLVM Clang 12 compiler benchmarks with the Core i9 11900K running from the newly-released Fedora Workstation 34 featuring these very latest compilers. The compiler benchmarks were carried out at multiple optimization levels on each compiler.

18 May 2021 - 13 Comments
LuxCoreRender 2.5 OptiX Performance Tested With 19 NVIDIA GPUs

Released last week was the LuxCoreRender 2.5 open-source physically based renderer. Significant with this v2.5 update is OptiX/RTX acceleration support in addition to its existing CUDA, OpenCL, and CPU render paths. Given that, here are some fresh benchmarks of LuxCoreRender 2.5 across an assortment of NVIDIA graphics cards.

18 April 2021 - 8 Comments
AVX / AVX2 / AVX-512 Performance + Power On Intel Rocket Lake

Here is a look at the AVX / AVX2 / AVX-512 performance on the Intel Core i9 11900K "Rocket Lake" when building a set of relevant open-source benchmarks limited to AVX, AVX2, and AVX-512 caps each time while also monitoring the CPU package power consumption during the tests for looking at the performance-per-Watt in providing some fresh reference metrics over AVX-512 on Linux with the latest Intel "Rocket Lake" processors.

7 April 2021 - 59 Comments
Benchmarking AMD Zen 3 With Predictive Store Forwarding Disabled

This past week AMD published a security analysis of AMD Zen 3's new Predictive Store Forwarding (PSF) functionality. In there they did acknowledge there is the possibility where bad PSF functionality could lead to a side-channel attack albeit the real-world exposure would be quite low. In any case they are allowing interested users to disable the Predictive Store Forwarding functionality, but what they didn't comment on in that paper was what performance overhead to expect if disabling PSF. So my Easter weekend turned into AMD Zen 3 PSF benchmarking.

4 April 2021 - 22 Comments
AMD AOCC 3.0 Compiler Performance With The EPYC 75F3 - Making Fast Even Faster

Launched last week with the AMD EPYC 7003 "Milan" processors was the AOCC 3.0 code compiler as AMD's downstream of LLVM Clang with various patches now catering to optimized for Zen 3. Last week some preliminary benchmarks of AOCC 3.0 on the Ryzen 9 5950X were carried out to good results. Since then I have begun putting AOCC 3.0 through its paces on a AMD EPYC 7003 series server to overall great results.

25 March 2021 - 2 Comments
Linux 5.12 Features Intel Xe VRR, Nintendo 64 Port + Clang LTO + Much More

The Linux 5.12 merge window was off to a rough start due to winter storms preventing Linus Torvalds from merging changes for nearly one week, but in any case he appears to have caught up and the Linux 5.12-rc1 kernel is expected later today to end out the merge window. Here is a look at the many exciting changes coming for Linux 5.12.

28 February 2021 - 9 Comments
GCC 10 vs. GCC 11 Compiler Performance On AMD Zen 3

After recently looking at the early LLVM Clang 12 compiler performance on the AMD Ryzen 9 5950X, in today's benchmarking is a look at how the GCC 11 compiler performance is looking in its near final state compared to GCC 10 under a variety of build CFLAGS/CXXFLAGS configurations on the AMD Zen 3 desktop.

24 February 2021 - 4 Comments

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