Welcome to LWN.net
LWN.net is a reader-supported news site dedicated to producing the best coverage from within the Linux and free software development communities. See the LWN FAQ for more information, and please consider subscribing to gain full access and support our activities.
[$] Atomic writes without tears
John Garry and Ted Ts'o led a discussion about supporting atomic writes for buffered I/O, without any torn (or partial) writes to the device, at the 2024 Linux Storage, Filesystem, Memory Management, and BPF Summit. It is something of a continuation of a discussion at last year's summit. The goal is to help PostgreSQL, which writes its data using 16KB buffered I/O; it currently has to do a lot of extra work to ensure that its data is safe on disk. A promise of non-torn, 16KB buffered writes would allow the database to avoid doing double writes.
[$] Allocator optimizations for transparent huge pages
The original Linux kernel, posted in 1991, ran on a system with a 4KB page size. Over 30 years later, most of us are still running on systems with 4KB pages, even though the amount of installed memory has grown by a few orders of magnitude. It is generally accepted that using large page sizes results in better performance for most applications, but allocating larger pages is often difficult. During a memory-management session at the 2024 Linux Storage, Filesystem, Memory-Management and BPF Summit, Yu Zhao presented his ideas on improving the allocation of huge pages in the kernel.
[$] Recent improvements to BPF's struct_ops mechanism
Kui-Feng Lee spoke early in the BPF track at the 2024 Linux Storage, Filesystem, Memory Management, and BPF Summit about some of the recent improvements to BPF. These changes were largely driven by the sched_ext work that David Vernet had covered in the previous talk. Lee focused on changes relevant to struct_ops programs, but several of those changes apply to all BPF programs.
[$] Readying DNF5 for Fedora 41
With the release of Fedora 40 it's time to start looking ahead to what Fedora 41 has in store. One of the largest changes planned for the next release is a switch to DNF5, a C++ rewrite of the DNF package manager. A previous attempt to make the switch, during the Fedora 39 cycle, was called off, and deferred to Fedora 41. The developers have had nearly a year to address compatibility problems and bring DNF5 to a state suitable to replace DNF4. Signs point to a successful switch in the upcoming release, though there may be a few surprises lurking for Fedora users.
[$] Large-folio support for shmem and tmpfs
The kernel contains a pair of related filesystems that, among other things, can be used for shared-memory applications; shmem is an internal mechanism used within the kernel, while the tmpfs filesystem is mounted and accessible from user space. As is the case elsewhere in the kernel, these subsystems would benefit from the addition of large-folio support. During a joint storage, filesystem, and memory-management session at the 2024 Linux Storage, Filesystem, Memory-Management and BPF Summit, Daniel Gomez talked about the work he is doing to add that support.
[$] A new swap abstraction layer for the kernel
Swapping may be a memory-management technique at its core, but its implementation also involves the kernel's filesystem and storage layers. So it is not surprising that a session on the kernel's swap abstraction layer, led by Chris Li at the 2024 Linux Storage, Filesystem, Memory-Management and BPF Summit, was held jointly by all three of those tracks. Li has some ambitious ideas for an improved subsystem, but getting to a workable implementation may not be easy.
[$] What's scheduled for sched_ext
David Vernet's second talk at the 2024 Linux Storage, Filesystem, Memory Management, and BPF Summit was a summary of the state of sched_ext, the extensible BPF scheduler that LWN covered in early May. In short, sched_ext is intended as a platform for rapid experimentation with schedulers, and a tool to let performance-minded administrators customize the scheduler to their workload. The patch set has seen several revisions, becoming more generic and powerful over time. Vernet spoke about what has been done in the past year, and what is still missing before sched_ext can be considered pretty much complete.
[$] The twilight of the version-1 memory controller
Almost immediately after the merging of control groups, kernel developers set their sights on reimplementing them properly. The second version of the control-group API started trickling into the kernel around the 3.16 release in 2014 and users have long since been encouraged to migrate, but support for (and users of) the initial API remain. At the 2024 Linux Storage, Filesystem, Memory-Management and BPF Summit, memory-management developers discussed whether (and when) it might be possible to remove the version-1 memory controller. The session was led by Shakeel Butt and (participating remotely) Roman Gushchin.
[$] LWN.net Weekly Edition for May 23, 2024
Posted May 23, 2024 1:25 UTC (Thu)The LWN.net Weekly Edition for May 23, 2024 is available.
Inside this week's LWN.net Weekly Edition
- Front: KeePassXC; GitLab CI for the kernel; Trinity; 6.10 Merge window; LSFMM+BPF coverage.
- Briefs: Vendor kernel white paper; io_uring; AlmaLinux steering committee; Alpine Linux 3.20.0; Neovim 0.10; Quotes; ...
- Announcements: Newsletters, conferences, security updates, patches, and more.
[$] Supporting larger block sizes in filesystems
In a combined storage and filesystem session at the 2024 Linux Storage, Filesystem, Memory Management, and BPF Summit, Luis Chamberlain led a discussion on filesystem support for block sizes larger than the usual 4KB page size, which followed up on discussion from last year. While the session was meant to look at the intersection of larger block sizes with atomic block writes that avoid torn (partial) writes (which was also discussed last year), it mostly focused on the filesystem side. Over time, the block sizes offered by storage devices have risen from the original 512 bytes; Chamberlain wanted to discuss filesystem support for block sizes larger than 4KB.
BitKeeper, Linux, and licensing disputes: How Linus wrote Git in 14 days (Graphite blog)
This Graphite blog post retells the history of the BitKeeper fiasco and the dawn of the Git era.
When we think of history, we often romanticize it as being born of a sudden stroke of inspiration. But the creation of git shows the far harsher reality of invention: a slowly escalating disagreement over a license; the need for a scrappy backup solution to unblock work; and then continued polishing and iteration through years and years, led not by the inventor, but rather a community.
For those who weren't around in those days, a perusal of the LWN coverage from the time might be of interest too, including:
- Our first mention of BitKeeper in October 1998
- Not quite open source, 1999
- Linus tries out BitKeeper, 2002
- The free software community and proprietary packages, 2002
- The kernel and BitKeeper part ways, 2005
- How Tridge reverse engineered BitKeeper, 2005
- The guts of Git, 2005
...and a lot more for those who care to search for it.
Security updates for Friday
Security updates have been issued by Fedora (chromium, libreoffice, and thunderbird), Red Hat (.NET 7.0, .NET 8.0, gdk-pixbuf2, git-lfs, glibc, python3, and xorg-x11-server-Xwayland), SUSE (firefox, opensc, and ucode-intel), and Ubuntu (cjson and gnome-remote-desktop).
KDE Gear 24.05.0
The KDE Project has announced the release of KDE Gear 24.05.0, with new features and updates for the more than 200 applications that are part of the project. In addition to new versions of the Dolphin file manager, Kdenlive video editor, and Elisa music player, this release includes five applications new to KDE Gear: the Audex CD-ripper application, an application Accessibility Inspector, the Francis Pomodoro timer, Kalm to teach breathing techniques, and a Sokoban-like game called Skladnik. See the full changelog for a complete list of changes.
Security updates for Thursday
Security updates have been issued by Debian (chromium), Fedora (chromium, libxml2, pgadmin4, and python-libgravatar), Mageia (ghostscript), Red Hat (389-ds:1.4, ansible-core, bind and dhcp, container-tools:rhel8, edk2, exempi, fence-agents, freeglut, frr, ghostscript, glibc, gmp, go-toolset:rhel8, grafana, grub2, gstreamer1-plugins-bad-free, gstreamer1-plugins-base, gstreamer1-plugins-good, harfbuzz, httpd:2.4, idm:DL1, idm:DL1 and idm:client modules, kernel, kernel-rt, krb5, LibRaw, libreoffice, libsndfile, libssh, libtiff, libX11, libxml2, libXpm, linux-firmware, motif, mutt, openssh, osbuild and osbuild-composer, pam, pcp, pcs, perl-Convert-ASN1, perl-CPAN, perl:5.32, pki-core:10.6 and pki-deps:10.6 modules, pmix, poppler, postgresql-jdbc, python-dns, python-jinja2, python-pillow, python27:2.7, python3.11, python3.11-cryptography, python3.11-urllib3, python39:3.9 and python39-devel:3.9 modules, qt5-qtbase, resource-agents, squashfs-tools, sssd, systemd, tigervnc, tomcat, traceroute, varnish:6, virt:rhel and virt-devel:rhel modules, vorbis-tools, webkit2gtk3, xorg-x11-server, xorg-x11-server-Xwayland, and zziplib), SUSE (chromium, perl, postgresql14, and python-sqlparse), and Ubuntu (klibc, linux-aws-hwe, openssl, and vlc).
Alpine Linux 3.20.0 released
Version 3.20.0 of the Alpine Linux distribution has been released with initial support for 64-bit RISC-V. Other important changes include updates to GNOME 46, KDE Plasma 6, and replacing Redis with Valkey due to Redis's adoption of a non-free license model. See the release notes for more on this release.
Security updates for Wednesday
Security updates have been issued by Debian (webkit2gtk), Fedora (kernel), Mageia (chromium-browser-stable, djvulibre, gdk-pixbuf2.0, nss & firefox, postgresql15 & postgresql13, python-pymongo, python-sqlparse, stb, thunderbird, and vim), Red Hat (go-toolset:rhel8, nodejs, and varnish:6), SUSE (gitui, glibc, and kernel), and Ubuntu (libspreadsheet-parseexcel-perl, linux-aws, linux-aws-5.15, linux-gke, linux-gcp, python-idna, and thunderbird).
AlmaLinux forms engineering steering committee
The AlmaLinux project has announced the formation of the AlmaLinux Engineering Steering Committee (ALESCo):
[It] is dedicated to guiding the technical direction of the AlmaLinux distribution on a day-to-day basis within the guidelines set forth by the board, ensuring its robustness, reliability, sustainability, and relevance in the open-source ecosystem. ALESCo will work collaboratively with, and oversee relevant technical-focused Special Interest Groups (SIGs) to achieve these goals. It is "air traffic control" for engineering matters.
The initial members of ALESCo appointed by the AlmaLinux OS Foundation board are Andrew Lukoshko, Ben Thomas, Cody Robertson, Elkhan Mammadli, Jonathan Wright, and Neal Gompa. The AlmaLinux Wiki has more information on the committee's activities and how to get involved.
Security updates for Tuesday
Security updates have been issued by AlmaLinux (firefox, nodejs, and thunderbird), Fedora (uriparser), Oracle (firefox and thunderbird), Slackware (mariadb), SUSE (cairo, gdk-pixbuf, krb5, libosinfo, postgresql14, and python310), and Ubuntu (firefox, linux-aws, linux-aws-5.15, and linux-azure).
Axboe: What's new with io_uring in 6.10
Jens Axboe describes the new io_uring features that will be a part of the 6.10 kernel release.
Bundles are multiple buffers used in a single operation. On the receive side, this means a single receive may utilize multiple buffers, reducing the roundtrip through the networking stack from N per N buffers to just a single one. On the send side, this also enables better handling of how an application deals with sends from a socket, eliminating the need to serialize sends on a single socket. Bundles work with provided buffers, hence this feature also adds support for provided buffers for send operations.
Security updates for Monday
Security updates have been issued by Debian (bind9, chromium, and thunderbird), Fedora (buildah, chromium, firefox, mingw-python-werkzeug, and suricata), Mageia (golang), Oracle (firefox and nodejs:20), Red Hat (firefox, httpd:2.4, nodejs, and thunderbird), and SUSE (firefox, git-cliff, and ucode-intel).