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[$] What's scheduled for sched_ext
David Vernet's second talk at the 2024 Linux Storage, Filesystem, Memory Management, and BPF Summit was a summary of the state of sched_ext, the extensible BPF scheduler that LWN covered a in early May. In short, sched_ext is intended as a platform for rapid experimentation with schedulers, and a tool to let performance-minded administrators customize the scheduler to their workload. The patch set has seen several revisions, becoming more generic and powerful over time. Vernet spoke about what has been done in the past year, and what is still missing before sched_ext can be considered pretty much complete.
[$] 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.
[$] The path to deprecating SPARSEMEM
The term "memory model" is used in a couple of ways within the kernel. Perhaps the more obscure meaning is the memory-management subsystem's view of how physical memory is organized on a given system. A proper representation of physical memory will be more efficient in terms of memory and CPU use. Since hardware comes in numerous variations, the kernel supports a number of memory models to match; see this article for details. At the 2024 Linux Storage, Filesystem, Memory-Management and BPF Summit, Oscar Salvador, presenting remotely, made the case for removing one of those models.
[$] Two sessions on CXL memory
Compute Express Link (CXL) is a data-center-oriented memory solution that, according to some in the industry, will yield large cost savings and performance improvements. Others are more skeptical. At the 2024 Linux Storage, Filesystem, Memory-Management and BPF Summit, two sessions covered CXL and how it will be supported in future kernels.
[$] Documenting page flags by committee
For every page of memory in the system, the kernel maintains a set of page flags describing how the page is used and various aspects of its current state. Space for page flags has been in chronic short supply, leading to a desire to eliminate or consolidate them whenever possible. That objective, though, is hampered by the fact that the purpose of many page flags is not well understood. In a memory-management-track session at the 2024 Linux Storage, Filesystem, Memory-Management and BPF Summit, Matthew Wilcox set out to cooperatively update the page-flag documentation to improve that situation.
[$] Merging msharefs
The problem of sharing page tables across processes has been discussed numerous times over the years, Khalid Aziz said at the beginning of his 2024 Linux Storage, Filesystem, Memory-Management and BPF Summit session on the topic. He was there to, once again, talk about the proposed mshare() system call (which, in its current form, is no longer actually a system call but the feature still goes by that name) and to see what can be done to finally get it into the mainline.
[$] Toward the unification of hugetlbfs
The kernel's hugetlbfs subsystem was the first mechanism by which the kernel made huge pages available to user space; it was added to the 2.5.46 development kernel in 2002. While hugetlbfs remains useful, it is also viewed as a sort of second memory-management subsystem that would be best unified with the rest of the kernel. At the 2024 Linux Storage, Filesystem, Memory-Management and BPF Summit, Peter Xu raised the question of what that unification would involve and what the first steps might be.
[$] The KeePassXC kerfuffle
KeePassXC is an open-source (GPLv3), cross-platform password manager with local-only data storage. The project comes with a number of build options that can be used to toggle optional features, such as browser integration and password database sharing. However, controversy ensued when Debian Developer Julian Klode decided to make use of these compile flags to disable these features to improve security in the keepassxc package uploaded to Debian unstable for the upcoming Debian 13 ("Trixie") release.
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).
Eight new kernel updates
The 6.9.1, 6.8.10, 6.6.31, 6.1.91, 5.15.159, 5.10.217, 5.4.276, and 4.19.314 stable kernels have been released. These versions include important fixes; as usual, Greg Kroah-Hartman advises users to update right away.
Security updates for Friday
Security updates have been issued by Fedora (chromium, firefox, and podman), Mageia (chromium-browser-stable, ghostscript, and java-1.8.0, java-11, java-17, java-latest), Red Hat (bind, Firefox, firefox, gnutls, httpd:2.4, and thunderbird), SUSE (glibc, opera, and python-Pillow), and Ubuntu (dotnet7, dotnet8, linux, linux-aws, linux-aws-5.4, linux-azure, linux-azure-5.4, linux-bluefield, linux-gcp, linux-gcp-5.4, linux-gkeop, linux-hwe-5.4, linux-ibm, linux-ibm-5.4, linux-iot, linux-kvm, linux-oracle, linux-oracle-5.4, linux-raspi, linux-raspi-5.4, linux-xilinx-zynqmp, linux, linux-aws, linux-aws-6.5, linux-azure, linux-azure-6.5, linux-gcp, linux-gcp-6.5, linux-hwe-6.5, linux-laptop, linux-lowlatency, linux-lowlatency-hwe-6.5, linux-nvidia-6.5, linux-oem-6.5, linux-oracle, linux-oracle-6.5, linux-raspi, linux-signed, linux-signed-aws, linux-signed-aws-6.5, linux-starfive, linux-starfive-6.5, linux, linux-aws, linux-azure-4.15, linux-gcp-4.15, linux-hwe, linux-kvm, linux-oracle, linux, linux-aws, linux-kvm, linux-lts-xenial, and linux, linux-azure, linux-azure-5.15, linux-azure-fde, linux-azure-fde-5.15, linux-gcp, linux-gcp-5.15, linux-gkeop, linux-gkeop-5.15, linux-hwe-5.15, linux-ibm, linux-ibm-5.15, linux-intel-iotg, linux-kvm, linux-lowlatency, linux-lowlatency-hwe-5.15, linux-nvidia, linux-oracle, linux-raspi).