Following the PLATYPUS discovery last year that CPU energy information could be used for possible side channel attacks, the Intel RAPL counters were not only restricted to root but the "amd_energy" driver for exposing CPU energy information on supported Zen series CPUs was also dialed back to root-only in the name of security. Linux 5.13 is introducing a new mechanism so AMD CPUs will be able to still read the energy counters even if not operating as root.
AMD News Archives
1,663 AMD open-source and Linux related news articles on Phoronix since 2006.
AMD last week published a security whitepaper on Zen 3's Predictive Store Forwarding (PSF) functionality introduced with Ryzen 5000 series and EPYC 7003 series processors. In the whitepaper they mentioned Linux patches were published for allowing this feature to be disabled if concerned about the security risk, well, today those patches were made public.
AMD published a security whitepaper this week looking at their Predictive Store Forwarding (PSF) feature that is new to Zen 3 series processors. AMD is going to allow customers to disable this performance feature as they think it may be vulnerable to a Spectre-like attack.
In the past few weeks since the introduction of the EPYC 7003 "Milan" processors there has finally been AMD Zen 3 "Znver3" tuning work that's been hurried into the GCC 11 compiler code-base ahead of its stable release in the coming weeks. That initial Zen 3 tuning work has also now been back-ported to the GCC 10 branch ahead of its next point release.
With AMD's busy Q1 of introducing the Radeon RX 6700 XT graphics card, introducing the Ryzen 5000 mobile series, the AMD EPYC 7003 "Milan" series launch, and continuing to advance their open-source/Linux software efforts, it was another busy quarter. Here is a look back from the Linux/open-source perspective of what interested readers the most.
Last week there were a few round of Zen 3 compiler patches published and quickly merged into the GCC 11 compiler code-base ahead of its imminent release, This week there is some new activity albeit fixes for this new "Znver3" target.
In addition to AMD EPYC 7003 "Milan" processors offering fantastic performance, another important highlight for these new Zen 3 server processors is SEV-SNP for upping the Secure Encrypted Virtualization capabilities. AMD has been offering SEV "Secure Nested Paging" patches via a GitHub repository while now they are working towards mainlining this feature for the Linux kernel.
On Monday, the AMD EPYC 7003 "Milan" launch day, we finally got to see some serious tuning begin for the Zen 3 "Znver3" CPU target in the GCC compiler after that initial code landed at the end of last year. Yesterday a second Zen 3 tuning patch was published and then today a third tuning patch has made it out.
With today's AMD EPYC 7003 "Milan" launch there is also the public availability of AOCC 3.0 as their LLVM/Clang downstream now carrying patches for optimized Zen 3 support.
GCC is in the process of seeing better support for AMD Zen 3 processors with its znver3 target.
AMD has announced that next week on 15 March they will be hosting a digital launch event for the EPYC 7003 "Milan" processors.
Of the performance-related changes with Linux 5.12 worth noting is faster AES-NI XTS performance for systems relying upon return trampolines "Retpolines" as part of the CPU's Spectre V2 mitigations. On the Intel side this primarily impacts older CPUs where Retpolines is still used while on the AMD side through Zen 3 the Retpolines is still relied upon, which as shown by these benchmarks is now much better off for AMD Ryzen AES XTS performance as measured by Cryptsetup.
Earlier this month at the virtual FOSDEM 2021 conference was an interesting presentation on how European developers are preparing for AMD-powered supercomputers and beginning to figure out the best approaches for converting existing NVIDIA CUDA GPU code to run on Radeon GPUs as well as whether writing new GPU-focused code with OpenMP device offload is worthwhile.
Due to an unfortunate misalignment of the Ryzen 5000 series launch and the Linux kernel cycles, CPU temperature monitoring for Ryzen 5000 (Zen 3) desktop CPUs isn't landing until now with the Linux 5.12 kernel cycle.
It looks like thanks to AMD's increasing sales and continuing successes in the enterprise space with more HPC wins and the like, AMD is hiring more Linux engineers. AMD currently has several interesting job openings on the Linux front.
While AMD has been crushing it when it comes to Linux performance and generally delivering good launch-day support, the one area many Linux/open-source advocates have been eager and hopeful to see change is around Coreboot support and ideally open-source firmware support such as by re-opening AGESA. Both inside and outside of AMD there continues being work in this direction.
The AMD "frequency invariance" saga with Linux 5.11 continues... While there was a patch to address the previously noted performance regression caused by the introduction of frequency invariance and seen when using the Schedutil governor, a new CPUFreq-side patch series has been proposed instead -- both of which are addressing the performance issue with this new kernel for AMD Zen 2 / Zen 3 systems.
Sent in today to DRM-Next ahead of the Linux 5.12 kernel cycle were "fixes" but some interesting items worth noting in this batch.
With the in-development Linux 5.11 kernel there are many great features and improvements especially for AMD users with some new drivers and other pleasant enhancements. But as I outlined back on Christmas day: Linux 5.11 Is Regressing Hard For AMD Performance With Schedutil. Fortunately, a fix is now en route to the Linux 5.11 kernel for fixing that performance regression affecting AMD Zen 2/3 desktops and servers.
Following Intel's product announcements yesterday, AMD CEO Dr. Lisa Su providing her virtual keynote this morning for the virtual CES 2021. Here are the highlights for how AMD is aiming to make 2021 even more exciting than their prior stellar year.
AMD is back on track publishing more Zen 3 compiler support patches for the LLVM compiler stack.
AMD this year not only delivered the very powerful Ryzen 5000 "Zen 3" desktop processors and initial Radeon RX 6000 "Big Navi" graphics cards but for exciting Linux users was the timely open-source support for the new GPUs well in advance (and also already preparing for some 2021 graphics products) as well as more timely support around Zen 3 thermal support and other additions. AMD's open-source timing is still improving although not yet optimal but all in it was a hell of a year for AMD Linux users.
A few days ago I noted nice AMD EPYC performance improvements with PostgreSQL when running on Linux 5.11 compared to prior kernels. I've confirmed that for even more AMD EPYC servers now that the PostgreSQL uplift is there, but other workloads are unfortunately regressing for both Ryzen and EPYC. Here's the start of an exciting Christmas benchmarking adventure looking at this change with Linux 5.11...
Just in time for the upcoming AMD Ryzen 5000 series mobile processors, it's looking like the S2idle support is finally coming together on Linux for increased power savings.
The Linux hardware monitoring "k10temp" driver is dropping support for reporting CPU voltage and current information for AMD Zen-based processors over lack of documentation for being able to properly support the functionality.
For those running PostgreSQL database servers (and potentially similar workloads) on AMD EPYC servers, Linux 5.11 is bringing a very nice Christmas gift in the form of better performance for at least some 2P server configurations.
The previously reported on work for frequency invariance calculations for AMD CPUs with a focus on the AMD EPYC 7002 series has been merged for Linux 5.11 as part of the "sched/core" material.
There are a lot of changes coming with Linux 5.11 and on the AMD side includes the likes of VanGogh and Dimgrey Cavefish graphics support, AMD EPYC Zen 3 support in the AMD_Energy driver, AMD RAPL Zen1/Zen2/Zen3 PowerCap support, an AMD SoC PMC driver, and the AMD Sensor Fusion Hub driver for Ryzen laptops is finally being mainlined... Another new addition was queued up this weekend by way of hwmon-next and that's the AMD SB-TSI sensor driver.
AMD's HIP C++ Runtime API / Kernel Language for allowing portable, single-source applications on AMD and NVIDIA GPUs can now run on CPUs too.
While AMD Smart Access Memory has already been supported under Linux for some time with its resizable BAR functionality, only now with all the excitement around the feature being promoted with the Ryzen 5000 series and Radeon RX 6000 series hardware is the Mesa driver code beginning to see some optimizations for it.
It's been just over one month since AMD launched the Ryzen 5000 series as the first processors part of the Zen 3 family. The Linux performance continues to be terrific with the Ryzen 5600X / 5800X / 5900X / 5950X parts in our continued benchmarking.
Earlier this week I looked at the Spectre mitigation performance impact on AMD Zen+ / Zen 2 / Zen 3 processors given the recent launch of the Ryzen 5000 series and those newest CPUs still requiring some mitigation handling. Questions were raised about the Spectre mitigation handling on Windows, so I ran some quick tests there as I happened to have a Windows 10 install on the Ryzen 9 5900X test box at the moment for some unrelated Windows vs. Linux gaming.
A few days ago AMD finally sent out the initial AMD Zen 3 "znver3" support to the GCC compiler with the LLVM Clang support to follow. That initial "-march=znver3" targeting support has now been merged for GCC 11.
In addition to AMD Zen 1/2/3 PowerCap RAPL support coming for the Linux 5.11 kernel, the hwmon-next Git branch has also queued initial support for Zen 3 processors within the AMD_Energy driver.
Following last month's release of the Ryzen 5000 "Zen 3" processors, AMD has now begun publishing their official compiler support for this extremely compelling processor family.
While we are still waiting to see what AMD might do for returning to open-source AGESA or better supporting Coreboot and the like, they are making some inroads with open-source firmware support -- beyond the context of Chromebooks where they continue to engage due to Google's engineering requirements. AMD is working to "align with the industry direction of open-source firmware stacks" with their initial focus being on open-source OpenBMC firmware support for their server platforms.
Thanks to work by AMD and SUSE engineers, the Linux kernel could soon be seeing frequency invariance support for EPYC 7002 "Rome" processors for yielding greater performance and power efficiency.
Now here is some darn interesting software news from SC20... AMD, which is in the process of acquiring Xilinx, is bringing the Radeon Open eCosystem "ROCm" stack to Xilinx hardware.
The work reported on back in October for RAPL PowerCap patches for AMD Zen CPUs from Zen 1 through Zen 3 are set to arrive with Linux 5.11 in early 2021.
Over the past week we have published our Linux performance reviews of the Ryzen 5 5600X, Ryzen 7 5800X, and Ryzen 9 5900X + 5950X "Zen 3" processors. For as much data that has been available in those reviews, here is even more data accumulating thanks to the open-source Phoronix Test Suite and OpenBenchmarking.org. Thousands of data points are building up for these very exciting AMD Zen 3 desktop processors.
AMD and IBM are this morning announcing a multi-year, joint development agreement focused on "building upon open-source software, open standards, and open system architectures to drive Confidential Computing in the cloud and support a broad range of accelerators across high-performance computing (HPC), and enterprise critical capabilities such as virtualization and encryption."
After last week sharing some Intel Tiger Lake benchmarks on Linux 5.10, the tables have turned and here are some similar tests when running Linux 5.10 on an AMD Ryzen 4000 series "Renoir" notebook.
In addition to the AMD Sensor Fusion Hub (SFH) driver coming with Linux 5.11 for improving Ryzen laptop support, the AMD SoC PMC driver is also under review for landing in this next kernel release.
Not only are AMD Ryzen 5000 series completely dominating in performance but they could soon see open-source Coreboot support as an alternative to the proprietary firmware/BIOS. Project X is an interesting effort around blob-free Coreboot/Oreboot support on AMD Zen.
Landing in Mesa 20.3 during this final week of feature development is support in RadeonSI Gallium3D for EGL_EXT_protected_surface. This long-standing EGL extension allows surfaces/windows to beset as protected and in which case the contents are only accessible to secure accesses. Outside/insecure accesses to the window (surface) contents are blocked.
Following the rumors earlier this month that AMD was in talks to acquire Xilinx, a deal has been announced this morning.
While AMD has landed Znver3 support in GNU Binutils, the company hasn't yet sent out patches for either the GCC or LLVM/Clang compilers in setting up the Zen 3 target with its new instructions or optimized scheduling model / cost table. But a basic implementation has been merged to LLVM for allowing "-march=znver3" based on the limited public details thus far.
For the Intel Tiger Lake Linux benchmarking thus far with the Core i7 1165G7 on the Dell XPS 13 9310 it's primarily been compared against the Ryzen 5 4500U and Ryzen 7 4700U on the AMD side since those are the only Renoir units within my possession. But a Phoronix reader recently provided me with remote access to his Lenovo ThinkPad X13 with Ryzen 7 PRO 4750U (8 cores / 16 threads) for seeing how the Tiger Lake performance compares against that higher-end SKU.
Since 2012 there has been a quirk in the Linux kernel to disable/override using ACPI _PSD data on all AMD processors as a workaround in turn for Windows-specific behavior that clashes with the semantics of the Linux ACPI CPUFreq driver for CPU frequency scaling. With AMD Zen 3 this quirk is no longer needed to behave correctly and thus Linux 5.10 is going to drop this eight year old quirk on Zen 3 and newer.
It was sadly too late for squeezing into the current Linux 5.10 merge window but it looks like for Linux 5.11 in early 2021 the AMD Sensor Fusion Hub "SFH" driver will make its long awaited debut.
1663 AMD news articles published on Phoronix.