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Katherine Johnson’s mathematical calculations helped guide some of America’s most important early space missions while she confronted the racial and gender barriers faced by Black women in twentieth-century America.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
io_uring[a] is a Linux kernel system call interface for storage device asynchronous I/O operations. It addresses performance issues with similar interfaces provided by functions like read()/write() or aio_read()/aio_write() for operations on data accessed by file descriptors.[2][3]: 2
It works by creating two circular buffers, called "queue rings", to track the submission and completion of I/O requests, respectively. For storage devices, these are called the submission queue (SQ) and completion queue (CQ).[4] Keeping these buffers shared between the kernel and application helps to boost the I/O performance by eliminating the need to issue extra and expensive system calls to copy these buffers between the two.[2][4][5] According to the io_uring design paper, the SQ buffer is writable only by consumer applications, and the CQ buffer is writable only by the kernel.[2]: 3
eBPF can be combined with io_uring.[6]
The Linux kernel has supported asynchronous I/O since version 2.5, but it was seen as difficult to use and inefficient.[7] This older API only supported certain niche use cases,[8] notably it only enables asynchronous operation when using the O_DIRECT flag and while accessing already allocated files. This prevents utilizing the page cache, while also exposing the application to complex O_DIRECT semantics. Linux AIO also does not support sockets, so it cannot be used to multiplex network and disk I/O.[9]
The io_uring kernel interface was adopted in Linux kernel version 5.1 (2019) to resolve the deficiencies of Linux AIO.[2][5][10] The liburing library provides an API to interact with the kernel interface easily from userspace.[2]: 12
In June 2023, Google's security team reported that 60% of the exploits submitted to their bug bounty program in 2022 were exploits of io_uring vulnerabilities. As a result, io_uring was disabled for apps in Android, and disabled entirely in ChromeOS as well as Google servers.[11] Docker also consequently disabled io_uring from their default seccomp profile.[12]
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Blocking during io_submit on ext4, on buffered operations, network access, pipes, etc. Some operations are not well-represented by the AIO interface. With completely unsupported operations like buffered reads, operations on a socket or pipes, the entire operation will be performed during the io_submit syscall, with the completion available immediately for access with io_getevents. AIO access to a file on a filesystem like ext4 is partially supported: if a metadata read is required to look up the data block (ie if the metadata is not already in memory), then the io_submit call will block on the metadata read. Certain types of file-enlarging writes are completely unsupported and block for the entire duration of the operation.
60% of the submissions exploited the io_uring component of the Linux kernel
liburing source repositoryio_uring source directory in the Linux kernel repository| Organization | |||||
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Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
The Linux kernel provides multiple interfaces to user-space and kernel-mode code. The interfaces can be classified as either application programming interface (API) or application binary interface (ABI), and they can be classified as either kernel–user space or kernel-internal.
NetworkManager is a daemon that sits on top of libudev and other Linux kernel interfaces (and a couple of other daemons) and provides a high-level interface for the configuration of the network interfaces to simplify the use of computer networks on Linux distributions.
Namespaces are a feature of the Linux kernel that partition kernel resources such that one set of processes sees one set of resources, while another set of processes sees a different set of resources. The feature works by assigning the same namespace type to a set of resources and processes, but allowing those namespaces to refer to distinctly isolated environments. This provides the illusion that a process or a process group is the sole user of the system's hardware and software resources. Examples of such resources include process IDs, hostnames, user IDs, file names, network interfaces, and inter-process communication (IPC) mechanisms. Linux namespaces, alongside cgroups (control groups), are the foundational technologies underpinning modern OS-level virtualization and Linux containerization platforms such as Docker, Kubernetes, LXC, and Podman. While cgroups dictate how much of a system's resources a process can use (such as CPU, memory, and disk I/O limits), namespaces dictate what a process is allowed to see and interact with. The term "namespace" is often used to denote a specific type of namespace (e.g., process ID namespace) as well as a particular space of names. A Linux system begins with a single initial namespace of each type, which is shared by all processes. Processes can subsequently create additional namespaces or join existing ones, allowing complex, nested isolation boundaries.
io_uring is a Linux kernel system call interface for storage device asynchronous I/O operations. It addresses performance issues with similar interfaces provided by functions like read()/write() or aio_read()/aio_write() for operations on data accessed by file descriptors.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Joe Louis.
