Post Syndicated from corbet original https://lwn.net/Articles/1094303/

The io_uring
subsystem is all about asynchronous execution; applications count on it
to not block — unless explicitly requested to. Within io_uring, maintaining
the “never blocks” guarantee has sometimes been a challenge, given that
many paths in the kernel were never designed for asynchronous execution.
This problem has been worked around, but at a significant cost to
performance. Now, io_uring maintainer Jens Axboe has posted an RFC patch set
with a somewhat radical (and potentially scary) solution to the problem.

Post Syndicated from corbet original https://lwn.net/Articles/1094963/

Version 51 of the GNOME desktop
environment has been released. The list of changes includes a number of
performance improvements, offline data and better transit information in
the Maps application, a new interface for the file previewer, and more.

Post Syndicated from corbet original https://lwn.net/Articles/1094962/

Security updates have been issued by AlmaLinux (.NET 10.0, .NET 8.0, .NET 9.0, corosync, firewalld, kernel, kernel-rt, libevent, libsoup, microcode_ctl, nginx:1.26, python-lxml, rsyslog, tesseract, and unbound), Debian (firefox-esr, mkvtoolnix, thunderbird, and tor), Fedora (open62541, php-pecl-mongodb2, python-django6, python-jwcrypto, and roundcubemail), Mageia (aom, cockpit, libgd, packagekit, and python-h2), Red Hat (corosync, delve, git-lfs, grafana-pcp, gstreamer1-plugins-base, libvirt, opentelemetry-collector, and rhc-worker-playbook), Slackware (mozilla-firefox and mozilla-thunderbird), SUSE (acl, attr, alloy, ansible-core, clamav, containerized-data-importer, corosync, cups, distribution, glibc, google-cloud-sap-agent, govulncheck-vulndb, gvfs, helm, jq, kbd, kubernetes1.34-apiserver, kubernetes1.35-apiserver, lcms2, libcupsfilters, liblzmasdk26, libzypp, zypper, mistral-vibe, opensc, openvpn, pcre2, python-jwcrypto, tomcat, tomcat10, and tomcat11), and Ubuntu (guix, libheif, perl, python-cryptography, sqlite3, and valkey).

Post Syndicated from corbet original https://lwn.net/Articles/1094762/

The Register looks
forward to the upcoming Fedora 45 release.

The biggest surprise is that Linux’s legacy in-kernel console – the
text-mode interface normally hidden beneath the GUI – has been
replaced with a software-controlled alternative.
The replacement is kmscon, a
userspace terminal emulator that has been in development for more
than a decade.

Post Syndicated from corbet original https://lwn.net/Articles/1094720/

Security updates have been issued by AlmaLinux (kernel, kernel-rt, libkcapi, nginx, nginx:1.24, openssl, osbuild-composer, perl, perl:5.32, python-tornado, rsync, and rust), Debian (cjose and nginx), Fedora (environment-modules, erlang, GitPython, knot, perl-Authen-SASL, python-configargparse, ruby, rubygems, and sblim-sfcb), Oracle (firefox, git-lfs, gstreamer1-plugins-base, kernel, libkcapi, nginx, nginx:1.26, openssl, osbuild-composer, perl, perl-YAML-Syck, postgresql18, python-tornado, and rust), Red Hat (fence-agents, git-lfs, microcode_ctl, osbuild-composer, podman, python-pyasn1, and resource-agents), SUSE (389-ds, ant, bson-devel, chirp-20260911, docker, gimp, google-cloud-sap-agent, hauler, kernel, kimi-code, libpcap, python-GitPython, python310, syncthing, yast2-samba-client, and zstd-jni), and Ubuntu (aom, imagemagick, kitty, openssh, phpseclib, policykit-1, python-sql, python-webob, shibboleth-sp, simplesamlphp, snapcast, srt, and suricata-update).

Post Syndicated from corbet original https://lwn.net/Articles/1093661/

The scheduling of block I/O requests has long
been a challenge for operating-system kernels. For many years, the
performance characteristics of rotating drives meant that putting
considerable resources into request ordering was worthwhile. In a world
with fast, solid-state drives, scheduling is more concerned with enforcing
fairness between competing users while being fast enough to keep up with
drives that can perform millions of I/O
operations per second. The blk-iocost I/O
controller was designed for the solid-state world and generally performs
well, but there is always a desire to do better. This patch
series from Tao Cui aims to make blk-iocost more flexible by enabling
the loading of a BPF program to make cost decisions.

Post Syndicated from corbet original https://lwn.net/Articles/1093929/

Just a reminder that prices for LWN subscriptions will increase after
September 15. Until then, the older rate still applies. See this article for details on this change.
Thanks, yet again, to all of our subscribers for your support — that is
what keeps LWN going.

Post Syndicated from corbet original https://lwn.net/Articles/1093962/

The 7.3-rc3 kernel prepatch is out for
testing. Linus said: “Another fairly large rc release, and again one
with a bigger filesystem footprint that we usually see.“

Post Syndicated from corbet original https://lwn.net/Articles/1093398/

Kernel developers do a lot of kernel builds. Since the kernel is not a
small program, those builds can take a fair amount of time, even on a fast
machine. The kernel also has a complex build system; it is probably fair
to say that few developers truly understand it, and fewer still are willing
to try to improve it. Lorenzo Stoakes, armed with LLM-based assistance,
decided to give it a try, though, and has managed to reduce the time it
takes to build a kernel — and not by a small amount.

Post Syndicated from corbet original https://lwn.net/Articles/1092555/

The restartable sequences feature is one of
the stranger corners of the kernel’s user-space interface; it provides a
way for user space to carry out simple lockless operations and be informed
if it is preempted over the course of an operation (and must, thus,
restart). Work merged in the 6.19 release to improve the performance of restartable
sequences broke the TCMalloc allocator,
which was relying on an undocumented (and unintended) kernel behavior.
Now, Olivier Dion is proposing an
addition to the restartable-sequences API that will bring TCMalloc back
into the fold; it does not make the restartable-sequences API any less
strange, though.

Post Syndicated from corbet original https://lwn.net/Articles/1092757/

The 7.3-rc2 kernel prepatch is out for
testing. Linus said:

This didn’t *feel* like a particularly busy rc2, but it clearly
was. rc2 is usually the quietest time when people take a breather
after the merge window and it takes a while to start finding
bugs. But not this time – this is a “full fat” rc release. […]

Nothing looks particularly odd, even if the rc2 timing is a bit
unusual. It might be just random, but we’ll obviously all blame it
on AI, because whether that’s really the cause or not, it’s an easy
thing to blame 😉

Post Syndicated from corbet original https://lwn.net/Articles/1092001/

Tiered-memory systems are built with multiple types of memory, each of
which has different performance characteristics. In addition to the usual
DRAM, a tiered system might also provide faster high-bandwidth memory or
slower CXL memory. On these systems, the placement of memory allocations
has a significant effect on the performance that a workload will obtain.
While work on tiered-memory improvements has been ongoing for years, it
feels like the pace has slowed a bit recently. Even so, there are a few
efforts underway, but they are facing questions about whether the tiering
design makes sense.

Post Syndicated from corbet original https://lwn.net/Articles/1090585/

The online publication industry, as a whole, is struggling, with challenges
coming from multiple directions. Thanks to the support of all of you, our
readers, LWN would appear to be doing better than most. But the world has
changed around us and, in particular, prices have changed considerably. By
now, you probably know where this is going: subscription prices at LWN will
be increasing as of September 15.

Post Syndicated from corbet original https://lwn.net/Articles/1089791/

By the time Linus Torvalds released
7.3-rc1 and closed the merge window for this release, 15,267 non-merge
changesets had been pulled into the mainline repository. That is the
second-highest commit count for an -rc1 release in the kernel’s history;
only the 6.7-rc1 release, which included nearly 3,000 commits of bcachefs
history, had more. About 13,000 of those commits entered the mainline
after the first 7.3 merge-window summary
was written so, needless to say, there are a lot of changes to cover.

Post Syndicated from corbet original https://lwn.net/Articles/1091421/

Linus has released 7.3-rc1 and closed the
merge window for this release. “Nothing really stands out – except for
the fact that it’s big. It’s not the biggest rc1 we’ve ever had, but it’s
certainly up there, at least in number of commits.” He pulled 15,267
commits during this merge window, making it the second busiest ever; only
6.7 has exceeded it.

Post Syndicated from corbet original https://lwn.net/Articles/1091231/

The results of the
Debian general-resolution vote on the use
of large language models have been posted; the winner is choice 5:
Responsible Use of Generative AI.

Debian neither endorses nor prohibits the use of generative AI
tools in the development, maintenance, or documentation of
software, packaging, documentation, and other media published
within the Debian Project. We recognize that such tools can
substantially improve the productivity of contributors when used
responsibly, allowing volunteers to spend more of their limited
time on work that requires technical expertise, judgment, review,
and collaboration.

The Debian Project nevertheless expects that all contributions
submitted to Debian, regardless of how and with which tools they
were produced, satisfy the same standards of quality, correctness,
maintainability, and legal compliance. The use of a generative AI
tool does not diminish the contributor’s responsibility for the
work they submit. Contributors are expected to understand, review,
test, and, where appropriate, modify AI-assisted output before
incorporating it into Debian.

Post Syndicated from corbet original https://lwn.net/Articles/1090381/

Virtualization can increase CPU utilization by allowing a large number of
virtual CPUs to share a smaller number of physical CPUs. The amount of CPU
time that is actually available does not change, though, so heavy activity
on too many virtual CPUs can lead to contention and significant performance
loss. The steal governor
patch series from Shrikanth Hegde is an attempt to address that problem
with a mechanism that allows virtual machines to voluntarily reduce the
number of virtual CPUs they use when contention is high.

Post Syndicated from corbet original https://lwn.net/Articles/1090582/

For people who would like to experiment with the multi-kernel Linux concept, Cong Wang has
announced the
release of mklinux v7.0-mk2.

mklinux lets one machine run several independent Linux kernels at
the same time on bare metal, without a hypervisor. A host kernel
owns a pool of CPUs, memory and PCI devices, carves that pool into
instances, and boots a spawn kernel into each instance through
kexec_file_load(). Every spawn kernel runs natively on its own
CPUs, its own physical memory and its own devices. Nothing is
emulated and nothing is trapped; the only thing shared is what you
choose to share.

Note that this is not the old MkLinux, which was a port to PowerPC
Macintosh systems.

Post Syndicated from corbet original https://lwn.net/Articles/1090099/

The
7.1.10,
6.18.46,
6.12.105,
6.6.153,
6.1.184,
5.15.217, and
5.10.266
stable kernels have all been released; each contains another set of
important fixes.

Post Syndicated from corbet original https://lwn.net/Articles/1090098/

From Jeremy Allison we have the
sad news of the passing of Steve French. He was the maintainer of the
kernel’s SMB filesystem code for many years, having only dropped that
role due to health issues in the last week. “I’ve known Steve for
over 20 years. He was a legend in the community, and a really good
friend. He will be greatly missed. Farewell Steve.” He will indeed be missed.