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LWN.net Weekly Edition for October 31, 2024

corbet — Thu, 31 Oct 2024 00:42:27 +0000

The LWN.net Weekly Edition for October 31, 2024 is available.

An update on Apple M1/M2 GPU drivers

jake — Wed, 30 Oct 2024 16:23:29 +0000

The kernel graphics driver for the Apple M1 and M2 GPUs is, rather famously, written in Rust, but it has achieved conformance with various graphics standards, which is also noteworthy. At the X.Org Developers Conference (XDC) 2024, Alyssa Rosenzweig gave an update on the status of the driver, along with some news about the kinds of games it can support (YouTube video, slides). There has been lots of progress since her talk at XDC last year (YouTube video), with, of course, still more to come.

A new approach to validating test suites

daroc — Tue, 29 Oct 2024 17:01:12 +0000

The first program that Martin Pool ever wrote, he said, had bugs; the ones he's writing now most likely have bugs too. The talk Pool gave at RustConf this year was about a way to try to write programs with fewer bugs. He has developed a tool called cargo-mutants that highlights gaps in test coverage by identifying functions that can be broken without causing any tests to fail. This can be a valuable complement to other testing techniques, he explained.

The performance of the Rust compiler

daroc — Mon, 28 Oct 2024 16:10:27 +0000

Sparrow Li presented virtually at RustConf 2024 about the current state of and future plans for the Rust compiler's performance. The compiler is relatively slow to compile large programs, although it has been getting better over time. The next big performance improvement to come will be parallelizing the compiler's parsing, type-checking, and related operations, but even after that, the project has several avenues left to explore.

AutoFDO and Propeller

jake — Mon, 28 Oct 2024 15:15:19 +0000

Rong Xu and Han Shen described the kernel-optimization techniques that Google uses in the toolchains track at the 2024 Linux Plumbers Conference. They talked about automatic feedback-directed optimization (AutoFDO), which can be used with the Propeller optimizer to produce kernels with better performance using profile information gathered from real workloads. There is a fair amount of overlap between these tools and the BOLT post-link optimizer, which was the subject of a talk that directly preceded this session.

OSI readies controversial Open AI definition

jzb — Fri, 25 Oct 2024 21:02:36 +0000

The Open Source Initiative (OSI) has been working on defining Open Source AI—that is what constitutes an AI system that can be used, studied, modified, and shared for any purpose—for almost two years. Its board will be voting on the Open Source AI Definition (OSAID) on Sunday, October 27, with the 1.0 version slated to be published on October 28. It is never possible to please everyone in such an endeavor, and it would be folly to make that a goal. However, a number of prominent figures in the open-source community have voiced concerns that OSI is setting the bar too low with the OSAID—which will undo decades of community work to cajole vendors into adhering to or respecting the original Open Source Definition (OSD).

Kernel optimization with BOLT

jake — Fri, 25 Oct 2024 19:39:48 +0000

A pair of talks in the toolchains track at the 2024 Linux Plumbers Conference covered different tools that can be used to optimize the kernel. First up was Maksim Panchenko to describe the binary optimization and layout tool (BOLT) that Meta uses on its production kernels. It optimizes the kernel binary by rearranging it to improve its code locality for better performance. A subsequent article will cover the second talk, which looked at automatic feedback-directed optimization (AutoFDO) and other related techniques that are used to optimize Google's kernels.

realloc() and the oversize importance of zero-size objects

corbet — Thu, 24 Oct 2024 15:36:41 +0000

Small objects can lead to large email threads. In this case, the GNU C Library (glibc) community has been having an extensive debate over the handling of zero-byte allocations. Specifically, what should happen when a program calls realloc() specifying a size of zero? This is, it seems, a topic about which some people, at least, have strong feelings.

LWN.net Weekly Edition for October 24, 2024

corbet — Thu, 24 Oct 2024 00:42:13 +0000

The LWN.net Weekly Edition for October 24, 2024 is available.

Toward safe transmutation in Rust

daroc — Wed, 23 Oct 2024 17:40:38 +0000

Currently in Rust, there is no efficient and safe way to turn an array of bytes into a structure that corresponds to the array. Changing that was the topic of Jack Wrenn's talk this year at RustConf: "Safety Goggles for Alchemists". The goal is to be able to "transmute" — Rust's name for this kind of conversion — values into arbitrary user-defined types in a safer way. Wrenn justified the approach that the project has taken to accomplish this, and spoke about the future work required to stabilize it.

Free-software foundations face fundraising problems

jzb — Wed, 23 Oct 2024 14:52:28 +0000

In July, at the GNOME annual general meeting (AGM), held at GUADEC 2024, the message from the GNOME Foundation board was that all was well, financially speaking. Not great, but the foundation was on a break-even budget and expected to go into its next fiscal year with a similar budget and headcount. On October 7, however, the board announced that it had had to make some cuts, including reducing its staff by two people. This is not, however, strictly a GNOME problem: similar organizations, such as the Python Software Foundation (PSF), KDE e.V., and the Free Software Foundation Europe (FSFE) are seeing declines in fundraising while also being affected by inflation.