Latest Breaking News On - Jonathan corbet - Page 8 : vimarsana.com

Flags for fchmodat() [LWN.net]

The extensible scheduler class [LWN.net]

PostgreSQL reconsiders its process-based model [LWN.net]

In the fast-moving open-source world, programs can come and go quickly; a tool that has many users today can easily be eclipsed by something better next week. Even in this environment, though, some programs endure for a long time. As an example, consider the PostgreSQL database system, which traces its history back to 1986. Making fundamental changes to a large code base with that much history is never an easy task. As fundamental changes go, moving PostgreSQL away from its process-oriented model is not a small one, but it is one that the project is considering seriously.

Concurrency-managed workqueues [LWN.net]

A "thread pool" is a common group of processes which can be called on to perform work at some future time. The kernel does not lack for thread pool implementations; indeed, there are more choices than one might like. Options include workqueues, the slow work mechanism, and asynchronous function calls - not to mention various private thread pool implementations found elsewhere in the kernel. It has long been thought that having just one thread pool mechanism would be better, but nobody, so far, has managed to put together a single implementation that everybody likes.

Toward a better definition for i_version [LWN.net]

Filesystems maintain a lot of metadata about the files they hold; most of this metadata is for consumption by user space. Some metadata, though, stays buried within the filesystem and is not visible outside of the kernel. One such piece of metadata is the file version count, known as i version. Current efforts to change how i version is managed and to make it visible to user space have engendered a debate on what i version actually means and what its behavior should be.

Scope-based resource management for the kernel [LWN.net]

A memory-folio update [LWN.net]

The folio project is not yet two years old, but it has already resulted in significant changes to the kernel s memory-management and filesystem layers. While much work has been done, quite a bit remains. In the opening plenary session at the 2022 Linux Storage, Filesystem, Memory-management and BPF Summit, Matthew Wilcox provided an update on the folio transition and led a discussion on the work that remains to be done.

Concurrent page-fault handling with per-VMA locks [LWN.net]

The kernel is, in many ways, a marvel of scalability, but there is a longstanding pain point in the memory-management subsystem that has resisted all attempts at elimination: the mmap lock. This lock was inevitably a topic at the 2022 Linux Storage, Filesystem, Memory-Management and BPF Summit (LSFMM), where the idea of using per-VMA locks was raised. Suren Baghdasaryan has posted an implementation of that idea but with an interesting twist on how those locks are implemented.

Generic iterators for BPF [LWN.net]

BPF programs destined to be loaded into the kernel are generally written in C but, increasingly, the environment in which those programs run differs significantly from the C environment. The BPF virtual machine and associated verifier make a growing set of checks in an attempt to make BPF code safe to run. The proposed addition of an iterator mechanism to BPF highlights the kind of features that are being added as well as the constraints placed on programmers by BPF.

Process-level kernel samepage merging control [LWN.net]

The kernel samepage merging (KSM) feature can save significant amounts of memory with some types of workloads, but security concerns have greatly limited its use. Even when KSM can be safely enabled, though, the control interface provided by the kernel makes it unlikely that KSM actually will be used. A small patch series from Stefan Roesch aims to change this situation by improving and simplifying how KSM is managed.