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[$] The PuzzleFS container filesystem
The last year or so has seen the posting of a few new filesystem types that are aimed at supporting container workloads. PuzzleFS, presented at the 2023 Kangrejos gathering by Ariel Miculas, is another contender in this area, but it has some features of its own, including a novel compression mechanism and an implementation written in Rust.
[$] User-space spinlocks with help from rseq()
Back in May, André Almeida presented some work toward the creation of user-space spinlocks using adaptive spinning. At that time, the work was stalled because there is, in Linux, currently no way to quickly determine whether a given thread is actually executing on a CPU. Some progress has since been made on that front; at the 2023 Open Source Summit Europe, Almeida returned to discuss how that difficulty might be overcome.
[$] Revisiting the kernel's preemption models (part 1)
All that Ankur Arora seemingly wanted to do with this patch set was to make the process of clearing huge pages on x86 systems go a little faster. What resulted was an extensive discussion on the difficulties of managing preemption correctly in the kernel. It may be that some changes will come to the plethora of preemption models that the kernel currently offers.
[$] LWN.net Weekly Edition for September 21, 2023
Posted Sep 21, 2023 6:54 UTC (Thu)The LWN.net Weekly Edition for September 21, 2023 is available.
Inside this week's LWN.net Weekly Edition
- Front: Python's limited C API; European cyber resilience act; Shrinkers; Moving physical pages; fstat() in glibc.
- Briefs: RIP Abraham Raji; JDK 21; PostgreSQL 16; FOSSY videos; 40 years of GNU; Quote; ...
- Announcements: Newsletters, conferences, security updates, patches, and more.
[$] Using the limited C API for the Python stdlib?
The "limited" C API for CPython extensions has been around for well over a decade at this point, but it has not seen much uptake. It is meant to give extensions an API that will allow binaries built with it to be used for multiple versions of CPython, because those binaries will only access the stable ABI that will not change when CPython does. Victor Stinner has been working on better definition for the API; as part of that work, he suggested that some of the C extensions in the standard library start using it in an effort for CPython to "eat its own dog food". The resulting discussion showed that there is still a fair amount of confusion about this API—and the thrust of Stinner's overall plan.
[$] The European Cyber Resilience Act
The security of digital products has become a topic of regulation in recent years. Currently, the European Union is moving forward with another new law, which, if it comes into effect in a form close to the current draft, will affect software developers worldwide. This new proposal, called the "Cyber Resilience Act" (CRA), brings mandatory security requirements on all digital products, both software and hardware, that are available in Europe. While it aims at a worthy goal, the proposal is causing a stir among open-source communities.
[$] Moving physical pages from user space
Processes in a Linux system run within their own virtual address spaces. Their virtual addresses map to physical pages provided by the hardware, but the kernel takes pains to hide the physical addresses of those pages; processes normally have no way of knowing (and no need to know) where their memory is located in physical memory. As a result, the system calls for memory management also deal in virtual addresses. Gregory Price is currently trying to create an exception to this rule with a proposal for a new system call that would operate on memory using physical addresses.
[$] Shrinking shrinker locking overhead
Much of the kernel's performance is dependent on caching — keeping useful information around for future use to avoid the cost of looking it up again. The kernel aggressively caches pages of file data, directory entries, inodes, slab objects, and much more. Without active measures, though, caches will tend to grow without bounds, leading to memory exhaustion. The kernel's "shrinker" mechanism exists to be that active measure, but shrinkers have some performance difficulties of their own. This patch series from Qi Zheng seeks to address one of the worst of those by removing some locking overhead.
[$] Why glibc's fstat() is slow
The fstat() system call retrieves some of the metadata — owner, size, protections, timestamps, and so on — associated with an open file descriptor. One might not think of it as a performance-critical system call, but there are workloads that make a lot of fstat() calls; it is not something that should be slowed unnecessarily. As it turns out, though, the GNU C Library (glibc) has been doing exactly that, but a fix is in the works.
LWN.net Weekly Edition for September 14, 2023
Posted Sep 14, 2023 0:59 UTC (Thu)The LWN.net Weekly Edition for September 14, 2023 is available.
Inside this week's LWN.net Weekly Edition
- Front: Bogus CVE entries; openSUSE Leap; Large anonymous folios; 6.6 Merge window; Arduino.
- Briefs: GCC stack protector vuln; "Privacy sandbox"; Linux 6.6-rc1; Ubuntu TPM disk encryption; New SymPy; Quotes; ...
- Announcements: Newsletters, conferences, security updates, patches, and more.
LibrePCB 1.0.0 Released
The 1.0 version of the LibrePCB
"free, cross-platform, easy-to-use electronic design automation suite to draw schematics and design printed circuit boards
".
As noted in a blog post back in May, a grant has helped spur development of the tool.
The focus for the release has been in adding features that were needed so that "there should be no show stopper anymore which prevents you from using LibrePCB for more complex PCB [printed circuit board] designs
".
New features include a 3D viewer and export format for working with designs in a mechanical computer aided design (CAD) tool, support for manufacturer part number (MFN) management, and lots of board editor features such as
thermal relief pads in planes, blind & buried vias,
keepout zones, and more. [Thanks to Alphonse Ogulla.]
Security updates for Monday
Security updates have been issued by Debian (bind9, elfutils, flac, ghostscript, libapache-mod-jk, lldpd, and roundcube), Fedora (linux-firmware, roundcubemail, and thunderbird), Mageia (curl, file, firefox/thunderbird, ghostpcl, libtommath, and nodejs), Oracle (kernel, open-vm-tools, qemu, and virt:ol and virt-devel:rhel), SUSE (bind, busybox, djvulibre, exempi, ImageMagick, libqb, libssh2_org, opera, postfix, python, python36, renderdoc, webkit2gtk3, and xrdp), and Ubuntu (accountsservice and open-vm-tools).
Kernel prepatch 6.6-rc3
The third 6.6 kernel prepatch is out for testing.
Unusually, we have a large chunk of changes in filesystems. Part of it is the vfs-level revert of some of the timestamp handling that needs to soak a bit more, and part of it is some xfs fixes. With a few other filesystem fixes too.
The multi-grain timestamp changes turned out to cause the occasional regression (timestamps that could appear to go backward) and were taken back out.
Saturday's stable kernel updates
The 6.5.5, 6.1.55, 5.15.133, 5.10.197, 5.4.257, 4.19.295, and 4.14.326 stable kernel updates have all been released; each contains another set of important fixes.
Security updates for Friday
Security updates have been issued by Debian (gsl), Fedora (dotnet6.0 and dotnet7.0), Oracle (libwebp), Slackware (bind, cups, and seamonkey), SUSE (kernel and rust, rust1.72), and Ubuntu (cups, flac, gnome-shell, imagemagick, and python3.5).
Security updates for Thursday
Security updates have been issued by Debian (mutt, netatalk, and python2.7), Fedora (chromium, golang-github-prometheus-exporter-toolkit, golang-github-xhit-str2duration, and golang-gopkg-alecthomas-kingpin-2), Oracle (dmidecode, frr, libwebp, open-vm-tools, and thunderbird), Red Hat (libwebp and open-vm-tools), SUSE (cups, frr, mariadb, openvswitch3, python39, qemu, redis7, rubygem-rails-html-sanitizer, and skopeo), and Ubuntu (bind9, cups, and libppd).
Stable kernel 5.10.196
The 5.10.196 stable kernel has been released. It fixes a single regression:
This release is only needed by any 5.10.y user that uses configfs, it resolves a regression in 5.10.195 in that subsystem. Note that many kernel subsystems use configfs for configuration so to be safe, you probably want to upgrade if you are not sure.
Security updates for Wednesday
Security updates have been issued by Debian (frr and libyang), Fedora (golang-github-prometheus-exporter-toolkit, golang-github-xhit-str2duration, golang-gopkg-alecthomas-kingpin-2, libpano13, and open-vm-tools), Oracle (firefox, frr, and thunderbird), Red Hat (dmidecode, kernel, kernel-rt, kpatch-patch, libwebp: critical, linux-firmware, mariadb:10.3, ncurses, postgresql:15, and virt:rhel and virt-devel:rhel), Scientific Linux (firefox, open-vm-tools, and thunderbird), SUSE (binutils, bluez, chromium, curl, gcc7, go1.20, go1.21, grpc, protobuf, python-Deprecated, python-PyGithub, python-aiocontextvars, python-avro, python-bcrypt, python-cryptography, python- cryptography-vectors, python-google-api-core, pyt, gstreamer-plugins-good, kernel, libcares2, libxml2, mdadm, mutt, and python-brotlipy), and Ubuntu (indent, linux, linux-aws, linux-aws-5.15, linux-azure, linux-azure-5.15, linux-azure-fde, linux-azure-fde-5.15, linux-gcp, linux-gcp-5.15, linux-gke, linux-gkeop, linux-gkeop-5.15, linux-hwe-5.15, linux-ibm, linux-ibm-5.15, linux-kvm, linux-lowlatency, linux-lowlatency-hwe-5.15, linux-nvidia, linux, linux-aws, linux-aws-5.4, linux-azure, linux-azure-5.4, 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-xilinx-zynqmp, linux, linux-aws, linux-aws-6.2, linux-azure, linux-azure-6.2, linux-azure-fde-6.2, linux-gcp, linux-gcp-6.2, linux-hwe-6.2, linux-ibm, linux-kvm, linux-lowlatency, linux-lowlatency-hwe-6.2, linux-oracle, linux-raspi, linux-starfive, linux, linux-aws, linux-kvm, linux-lts-xenial, linux-oem-6.0, linux-oem-6.1, and memcached).
JDK 21 released
JDK 21, the reference implementation of the Java 21 language specification,
has
been released. "This release includes fifteen JEPs [1], including
the final versions of Record Patterns (440), Pattern Matching for switch
(441), and Virtual Threads (444)
".