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.

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.

For those wondering about the state of speculative execution vulnerabilities and what software-based mitigations are required for Intel's new Rocket Lake processors, here is the rundown along with benchmarks when disabling those present Linux kernel mitigations.

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.

This week alongside the EPYC 7003 series launch was the introduction of AOCC 3.0 as AMD's Zen-optimized LLVM/Clang downstream. We have started putting this updated compiler through its paces to see what it means for AMD Zen 3 performance.

With GCC 11 stable likely to be released next month, here is the latest in our compiler testing against the current GCC 10 stable release. This round of tests was carried out on a System76 Thelio Major with Ryzen Threadripper 3990X HEDT processor.

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.

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.

With LLVM 12 due for release next month and GCC 11 not being far behind, it's the season for fresh compiler benchmarks. In today's article is a look at the AMD Ryzen 9 5950X (Zen 3) compiler performance between LLVM Clang 11.1 against the current LLVM Clang 12.0 Git development code in its feature-frozen state.

Now with the CPUFreq fix landing this week in Linux Git, the mainline Linux 5.11 kernel in its near final state is looking in very good shape for AMD Zen 2/3 hardware from Ryzen laptops and desktops through EPYC servers. The Linux 5.11 development kernel was regressed for the better part of the past two months but now that the frequency invariance regression is addressed, not only is the regression gone but generally is performing much better compared to prior kernel versions.

For those following the saga of the AMD frequency invariance regression on Linux 5.11 since the Christmas investigative benchmarking looking at the performance regressions, everything now looks like it will be buttoned up in time for the Linux 5.11 stable release. As noted yesterday, there was a curve ball this week in that the patch proposed by SUSE's Giovanni Gherdovich in January to address the frequency invariance regression was turned down by the Linux power management maintainer and instead he (Rafael Wysocki of Intel) proposed an alternative patch that instead modified the CPUFreq driver. Given it's getting late into the cycle, it's been a mad rush of re-conducting benchmarks on this new kernel patch and now it looks like that solution will be sent in the coming days for Linux 5.11.

With a pending patch, the Linux 5.11 AMD Zen 2 / Zen 3 performance is looking very good as far as the out-of-the-box performance is concerned when using Schedutil as is becoming the increasingly default CPU frequency scaling governor on more distributions / default kernels. With the previously noted Linux 5.11 regression addressed from when the AMD CPU frequency invariance support was first introduced, the Schedutil performance from small Ryzen systems up through big EPYC hardware is looking quite good. But how much upside is left in relation to the optimal CPU frequency scaling performance with the "performance" governor? Here is a look at those benchmarks on Ryzen and EPYC for Schedutil vs. Performance on a patched Linux 5.11 kernel.

While the initial AMD Linux 5.11 performance regression written about at the end of last year was of much concern given the performance hits to AMD Zen 2 / Zen 3 processors with the out-of-the-box "Schedutil" governor, with a pending patch the regression is not only addressed but in various workloads we continue seeing better performance than even compared to Linux 5.10. Here is the latest from several more days of extensive performance testing.

Following last month's initial benchmarks of the AMD "znver3" support that landed in the GCC 11 compiler was a request by a premium supporter to see the AMD Zen 3 benchmarks at more compiler optimizations. Well, here are those numbers for those wanting to pursue aggressive compiler optimizations on a shiny AMD Ryzen 9 5950X.

With this week marking three years since Spectre and Meltdown were made public in ushering in a wave of CPU security disclosures that followed and mitigations that often resulted in measurable performance hits, here is a look at how the performance costs stand today with various new and older Intel CPUs as well as AMD processors too. This article is looking at the current performance costs under Linux with the default mitigations and then the run-time disabling of the relevant mitigations for each of the processors under test while using an up-to-date Ubuntu 20.10 paired with the new Linux 5.10 LTS kernel.

Phoronix Test Suite 10.2 is available today as the latest quarterly (Q1-2021) feature update to our open-source automated benchmarking framework for Linux, macOS, Solaris, Windows, and BSD platforms.

Back on Christmas I wrote about Linux 5.11 regressing for AMD performance on Zen 2 and newer systems where the just-added CPU frequency invariance support was often hurting various workloads when using the default "Schedutil" scheduler utilization frequency scaling governor. Since then and through the holidays I have been carrying out many more benchmarks looking at the Linux 5.11 performance with a particular focus on the AMD desktop/server platforms.

There are many new features with the Linux 5.11 kernel that is presently under development but one of the ones I've been more curious about for how well it works is the Intel "workload hints" that can be passed via its thermal framework. This is about providing the system with hints of workloads being run to optimize the thermal/power properties.

The Linux 5.11 merge window has been open the past two weeks following the debut of Linux 5.10 but is set to close today. A lot of new features and exciting improvements were merged for Linux 5.11 although it is somewhat of a bumpy ride at the moment but should be buttoned up and ready for its stable release come February.

It's not the Grinch in 2020 that stole Christmas, but the Schedutil CPU frequency scaling governor on the in-development Linux 5.11 kernel that is thrashing performance for AMD Zen 2 and newer. Distributions like Ubuntu, Fedora, and Manjaro are beginning to use CPUFreq Schedutil by default on newer kernels and thus leading to a very bad initial/out-of-the-box experience with the current behavior on the early Linux 5.11 code.

At the start of the month AMD released AOCC 2.3 as the newest version of the AMD Optimizing C/C++ Compiler. AOCC is one of several LLVM/Clang downstream versions maintained by the company with this one being about delivering flagship AMD Zen family compiler support. From an AMD EPYC 7002 "Rome" series processor I recently wrapped up fresh benchmarks of AOCC 2.3 against the current GCC 10 and Clang 11 compiler releases.

Last week AMD published their Zen 3 support for GCC code compiler. That initial support, which has already been merged into GCC 11, is the initial support flipping on newly supported instructions but not yet offering any tuned scheduler model or other optimizations compared to the existing Zen 2 path. In any case, here is a look at the performance changes with building the open-source benchmarks under test with "znver3" compared to the prior Zen 2 and Zen 1 targets along with generic x86_64 and then also looking at the performance if catering the compiler targets for Intel's Skylake and Haswell processors.

Last week I provided some benchmarks looking at the IBM POWER9 mitigation for the L1 data cache needing to be flushed upon entering the kernel and on user accesses due to a recently disclosed vulnerability. POWER9 allows speculatively operating on validated data in the L1 cache, but when it comes to incompletely validated data paired with other side channels it could lead to local users potentially obtaining improper access to data in the L1 data cache. When benchmarking the impact on a POWER9 4c/16t CPU the overall impact was fairly modest while since then I fired up some benchmarks as well on a large POWER9 server with 44 cores / 176 threads to see the performance impact of this default Linux kernel change.

With this month's release of Chrome 87 having more performance improvements while Firefox 83 debuted with its "Warp" JavaScript improvements, it's a good time for some fresh Linux web browser benchmarks of these two main options. Plus with Firefox 84 to begin enabling WebRender by default in some Linux configurations, there is also a fresh run of Firefox with WebRender enabled.

One area not talked about much for Intel's latest Tiger Lake processors are hardened CPU security mitigations against the various speculative execution vulnerabilities to date. What's peculiar about Tiger Lake though is now if disabling the configurable mitigations it can actually result in worse performance than the default mitigated state. At least that's what we are seeing so far with the Core i7 1165G7 on Ubuntu 20.10 Linux is the opposite of what we have been seeing on prior generations of hardware.

Last week a new vulnerability was made public for IBM POWER9 processors resulting in a mitigation of the processor's L1 data cache needing to be flushed between privilege boundaries. Due to the possibility of local users being able to obtain data from the L1 cache improperly when this CVE is paired with other side channels, the Linux kernel for POWER9 hardware is flushing the L1d on entering the kernel and on user accesses. Here are some preliminary benchmarks looking at how this security change impacts the overall system performance.

Now that the Samsung-contributed open-source exFAT file-system kernel driver has matured quite nicely since being merged earlier this year as a replacement to the short-lived staging exFAT driver based on an older code-base, here is a look at how exFAT is performing on the Linux 5.9 kernel compared to EXT4 and F2FS as well as the existing exFAT FUSE file-system implementation.

Making use of "-march=tigerlake" for building optimized binaries catering to Intel's latest-generation processors is well worth it on the likes of GCC 11. Out of the new instruction set extensions on Tiger Lake is more uplift than we have seen out of recent Intel generations and comparing the different "-march=" targets shows significant performance benefits if you don't mind compiling your own software from source.

The Linux 5.10 merge window is set to close this afternoon followed by around seven weeks worth of release candidates before the stable kernel release in December. As usual here is our look at the many new features set to premiere with this next version of the Linux kernel.

With Ubuntu 20.10 due for release this week I have begun testing near-final Ubuntu 20.10 builds on many more systems in the lab. Larger than our normal distribution/OS comparisons, here is the culmination of running hundreds of benchmarks (366 tests to be exact) under both Ubuntu 20.04 LTS with all available updates and then again on the Ubuntu 20.10 development state while testing on Intel Comet Lake.