Software Archives
Intel To Ring In 2022 With New, Faster AV1 Encoder Release

Intel in cooperation with the Alliance for Open Media continues developing SVT-AV1 as the flagship CPU-based AV1 video encoder. With the next SVT-AV1 update there are performance optimizations as well as several new preset levels allowing for even greater performance. Here are some early benchmarks of that updated SVT-AV1.

31 December 2021 - 12 Comments
AMD AOCC 3.2 vs. GCC vs. Clang Compiler Performance On Zen 3

Earlier this month AMD released AOCC 3.2 as the newest version of their LLVM/Clang-based compiler focused on delivering optimized Zen performance. With our initial AMD AOCC 3.2 benchmarks on Zen 3, there is nice incremental improvement compared to the prior 3.x releases. But how does this AMD-optimized compiler stack up against the upstream LLVM Clang and GCC compilers? Here is a look at the AMD AOCC performance against the current Clang and GCC C/C++ compilers.

29 December 2021 - 12 Comments
AMD AOCC 3.2 Helps Squeeze A Bit More Out Of Zen 3

Released earlier this month was AMD's AOCC 3.2 compiler based on LLVM/Clang/Flang that provides optimized support for AMD Zen processors. I've been running some benchmarks of AOCC 3.2 compared to prior AMD Optimizing C/C++ Compiler releases and this newest release has been helpful in squeezing a bit more out of Zen 3.

22 December 2021 - 7 Comments
GCC 12 Compiler Performance Is Looking Good For Intel Alder Lake

GCC 12 is nearing release in a few months time as the annual feature update to the GNU Compiler Collection for this Free Software Foundation backed code compiler. On top of new C/C++ language features and various optimization improvements, there is updated tuning for Intel's new Alder Lake processors. Here are some early GCC 11.2 vs. GCC 12 development benchmarks looking at the performance on a Core i5 12600K.

13 December 2021 - 7 Comments
Is It Worthwhile Running Intel Alder Lake With mitigations=off?

Over the past month of trying out Intel Alder Lake processors on Linux, one of the questions that has come up a few times but not readily disclosed is whether it's still worthwhile on this latest-generation process to boot with "mitigations=off" to disable CPU security mitigations to help squeeze out some otherwise lost performance. Here are some benchmarks to answer that questions.

2 December 2021 - 25 Comments
AMD P-State v4 Linux Testing On A Ryzen 5 5500U

With AMD having published a new revision to their AMD P-State Linux CPU frequency scaling driver that they are working towards mainlining with a goal of better power efficiency on Linux, here are some initial benchmarks of that new patch series when using a Ryzen 5 5500U notebook.

24 November 2021 - 14 Comments
Linux 5.16 Features Include FUTEX2, Intel AMX, Folios, DG2/Alchemist, More Apple Silicon Support

Now that the Linux 5.16 merge window has ended with yesterday's Linux 5.16-rc1 release, here is my lengthy original overview of what I find most interesting out of this new kernel version. Linux 5.16 won't be out as stable until around the end of the calendar year or early next year, but it will sure make one nice Christmas gift with all of the shiny new features in tow.

15 November 2021 - 8 Comments
Linux 5.16's New Cluster Scheduling Is Causing Regression, Further Hurting Alder Lake

Linux 5.16-rc1 is coming out later today and already I'm seeing some fallout in the new kernel's performance... In particular, bad news for Alder Lake that is already seeing the Linux performance trailing Windows 11 seemingly due to the lack of Thread Director integration right now in the kernel and any other missing optimizations around Intel's hybrid architecture. A new feature of Linux 5.16 is unfortunately having unintended regressions for Alder Lake with at least the flagship Core i9 12900K. Here are the results from the latest kernel bisecting that uncovered this latest upstream slowdown.

14 November 2021 - 71 Comments
The "What If" Performance Cost To Kernel Page Table Isolation On AMD CPUs

Made public this week by CPU security researchers at Graz University of Technology and CISPA Helmholtz Center for Information Security was the research paper published "AMD Prefetch Attacks through Power and Time". The paper points to AMD CPUs suffering from a side-channel leakage vulnerability through timing and power variations of the PREFETCH instruction. The paper argues that AMD CPUs should activate stronger page table isolation by default. AMD has now published their security response where they are not recommending any mitigation changes at this time. But what if Kernel Page Table Isolation (KPTI/PTI) proves necessary for AMD CPUs? Here are some initial benchmarks showing what that performance impact could look like.

15 October 2021 - 28 Comments
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 - 25 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

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