LWN.net's Journal
[Most Recent Entries]
[Calendar View]
Wednesday, May 8th, 2019
| Time |
Event |
| 2:13p |
Security updates for Wednesday
Security updates have been issued by Arch Linux (dovecot, kernel, linux-zen, munin, nautilus, perl-email-address, and tcpreplay), Debian (atftp), Fedora (perl-YAML and teeworlds), Mageia (java-1.8.0-openjdk, ldb, libsolv, and putty/filezilla/wxgtk), openSUSE (freeradius-server, libjpeg-turbo, pacemaker, rubygem-actionpack-5_1, wpa_supplicant, and yubico-piv-tool), Red Hat (chromium-browser, container-tools:rhel8, edk2, firefox, flatpak, ghostscript, httpd:2.4, mod_auth_mellon, openwsman, python-jinja2, python27:2.7, python3, python36:3.6, redhat-virtualization-host, systemd, and wget), SUSE (freeradius-server), and Ubuntu (ghostscript and wpa). | | 2:21p |
Stable kernel updates Stable kernels 5.0.14, 4.19.41, 4.14.117, and 4.9.174 have been released. As usual there are important fixes and users should upgrade. | | 3:01p |
[$] Taking ZUFS upstream
At the 2018 Linux Storage, Filesystem, and Memory-Management Summit
(LSFMM), Boaz Harrosh introduced the ZUFS
filesystem. At this year's event, he was back to talk about what it
would take to merge ZUFS into the mainline. ZUFS, which Harrosh pronounced
as both "zoo-eff-ess"
and "zoofs", has been running in production for his employer's (NetApp's)
customers for some time now, so he wondered if it was something that could
go upstream. | | 3:48p |
[$] Alignment guarantees for kmalloc()
kmalloc() is one of the kernel's fundamental memory-allocation
primitives for relatively small objects. Most of the time, developers
don't worry about the alignment of memory returned from
kmalloc(), and things generally just work. But, Vlastimil Babka
said during a plenary session at the 2019 Linux Storage,
Filesystem, and Memory-Management Summit, every now and then
kmalloc() will do something surprising. He proposed tightening
the guarantees around object alignment in the hope of generating fewer
surprises in the future. | | 4:27p |
[$] Improving access to physically contiguous memory
For years, kernel developers have been told to avoid allocating large chunks of
physically contiguous memory; as the system runs and memory becomes
fragmented, satisfying such allocations becomes increasingly difficult.
But, as Zi Yan pointed out in a memory-management track session at the 2019
Linux Storage, Filesystem, and Memory-Management Summit, there are times
when contiguous memory is useful. In this session, the memory-management
developers discussed ways to make such allocations more likely to succeed. | | 5:35p |
[$] How to get rid of mmap_sem
The mmap_sem lock used in the memory-management subsystem has been
a known scalability problem for years, but it has proved difficult to
remove. During a session in the memory-management track of the 2019 Linux
Storage, Filesystem, and Memory-Management Summit, Laurent Dufour and
Matthew Wilcox discussed a possible solution: replacing the red-black tree
currently used to track virtual memory areas (VMAs) with a new data
structure called a "maple tree". | | 6:51p |
[$] Memory management for 400Gb/s interfaces
Christoph Lameter has spent years improving Linux for high-performance
computing tasks. During the memory-management track of the 2019 Linux
Storage, Filesystem, and Memory-Management Summit, he talked about the
problem of keeping up with a 400Gb/s network interface. At that speed,
there simply is no time for the system to get its work done. Some ways of
improving the situation are in sight, but it's a hard problem overall and,
despite some progress, the situation is getting worse. | | 8:03p |
[$] Presenting heterogeneous memory to user space
Computer memory architecture is growing more complex over time, with
different types of memory attached to a CPU via a number of paths. The
kernel development community is duly working to make this memory available
to user space in an equally diverse set of ways. Two sessions at the 2019
Linux Storage, Filesystem, and Memory-Management Summit presented possible
mechanisms and APIs to allow programs to work with the types of memory they
need. | | 10:21p |
[$] Inheritance versus composition
The idea of "inheritance" is something that most students learn about early
on when they are studying object-oriented programming (OOP). But one of
the seminal books about OOP recommends favoring "composition" over
inheritance. Ariel Ortiz came to PyCon in Cleveland, Ohio to describe the
composition pattern and to explain the tradeoffs between using
it and inheritance. |
|