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EBPF
eBPF (often aliased BPF) is a technology that can run sandboxed programs in a privileged context such as the operating system kernel. It is used to safely and efficiently extend the capabilities of the kernel at runtime without requiring to change kernel source code or load kernel modules. Safety is provided through an in-kernel verifier which performs static code analysis and rejects programs which crash, hang or otherwise interfere with the kernel negatively. Loaded programs which passed the verifier are either interpreted or in-kernel JIT compiled for native execution performance. The execution model is event-driven and with few exceptions run-to-completion, meaning, programs can be attached to various hook points in the operating system kernel and are run upon triggering of an event. eBPF use cases include (but are not limited to) networking such as XDP, tracing and security subsystems. Given eBPF's efficiency and flexibility opened up new possibilities to solve productio ...
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Berkeley Packet Filter
The Berkeley Packet Filter (BPF) is a technology used in certain computer operating systems for programs that need to, among other things, analyze network traffic. It provides a raw interface to data link layers, permitting raw link-layer packets to be sent and received. In addition, if the driver for the network interface supports promiscuous mode, it allows the interface to be put into that mode so that all packets on the network can be received, even those destined to other hosts. BPF supports filtering packets, allowing a userspace process to supply a filter program that specifies which packets it wants to receive. For example, a tcpdump process may want to receive only packets that initiate a TCP connection. BPF returns only packets that pass the filter that the process supplies. This avoids copying unwanted packets from the operating system kernel to the process, greatly improving performance. The filter program is in the form of instructions for a virtual machine, which are ...
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Linux Foundation
The Linux Foundation (LF) is a non-profit technology consortium founded in 2000 as a merger between Open Source Development Labs and the Free Standards Group to standardize Linux, support its growth, and promote its commercial adoption. Additionally, it hosts and promotes the collaborative development of open source software projects. It is a major force in promoting diversity and inclusion in both Linux and the wider open source software community. The foundation was launched in 2000, under the Open Source Development Labs (OSDL) and became the organization it is today when OSDL merged with the Free Standards Group (FSG). The Linux Foundation sponsors the work of Linux creator Linus Torvalds and lead maintainer Greg Kroah-Hartman. Furthermore, it is supported by members, such as AT&T, Cisco, Fujitsu, Google, Hitachi, Huawei, IBM, Intel, Meta, Microsoft, NEC, Oracle, Orange S.A., Qualcomm, Samsung, Tencent, and VMware, as well as developers from around the world. In recent y ...
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Loadable Kernel Module
In computing, a loadable kernel module (LKM) is an object file that contains code to extend the running kernel, or so-called ''base kernel'', of an operating system. LKMs are typically used to add support for new hardware (as device drivers) and/or filesystems, or for adding system calls. When the functionality provided by an LKM is no longer required, it can be unloaded in order to free memory and other resources. Most current Unix-like systems and Microsoft Windows support loadable kernel modules under different names, such as kernel loadable module (kld) in FreeBSD, kernel extension (kext) in macOS (although support for third-party modules is being dropped), kernel extension module in AIX, kernel-mode driver in Windows NT and downloadable kernel module (DKM) in VxWorks. They are also known as kernel loadable modules (or KLM), and simply as kernel modules (KMOD). Advantages Without loadable kernel modules, an operating system would have to include all possible anticipated fu ...
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Seccomp
seccomp (short for secure computing mode) is a computer security facility in the Linux kernel. seccomp allows a process to make a one-way transition into a "secure" state where it cannot make any system calls except exit(), sigreturn(), read() and write() to already-open file descriptors. Should it attempt any other system calls, the kernel will either just log the event or terminate the process with SIGKILL or SIGSYS. In this sense, it does not virtualize the system's resources but isolates the process from them entirely. seccomp mode is enabled via the system call using the PR_SET_SECCOMP argument, or (since Linux kernel 3.17) via the system call. seccomp mode used to be enabled by writing to a file, /proc/self/seccomp, but this method was removed in favor of prctl(). In some kernel versions, seccomp disables the RDTSC x86 instruction, which returns the number of elapsed processor cycles since power-on, used for high-precision timing. seccomp-bpf is an extension to seccomp ...
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Windows
Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for servers, and Windows IoT for embedded systems. Defunct Windows families include Windows 9x, Windows Mobile, and Windows Phone. The first version of Windows was released on November 20, 1985, as a graphical operating system shell for MS-DOS in response to the growing interest in graphical user interfaces (GUIs). Windows is the most popular desktop operating system in the world, with 75% market share , according to StatCounter. However, Windows is not the most used operating system when including both mobile and desktop OSes, due to Android's massive growth. , the most recent version of Windows is Windows 11 for consumer PCs and tablets, Windows 11 Enterprise for corporations, and Windows Server 2022 for servers. Genealogy By marketing ...
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Linus Torvalds
Linus Benedict Torvalds ( , ; born 28 December 1969) is a Finnish software engineer who is the creator and, historically, the lead developer of the Linux kernel, used by Linux distributions and other operating systems such as Android. He also created the distributed version control system Git. He was honored, along with Shinya Yamanaka, with the 2012 Millennium Technology Prize by the Technology Academy Finland "in recognition of his creation of a new open source operating system for computers leading to the widely used Linux kernel." He is also the recipient of the 2014 IEEE Computer Society Computer Pioneer Award and the 2018 IEEE Masaru Ibuka Consumer Electronics Award. Life and career Early years Torvalds was born in Helsinki, Finland, the son of journalists Anna and Nils Torvalds, the grandson of statistician Leo Törnqvist and of poet Ole Torvalds, and the great-grandson of journalist and soldier Toivo Karanko. His parents were campus radicals at the University of H ...
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Computer Security Software
Computer security software or cybersecurity software is any computer program designed to influence information security. This is often taken in the context of defending computer systems or data, yet can incorporate programs designed specifically for subverting computer systems due to their significant overlap, and the adage that the best defense is a good offense. The defense of computers against intrusion and unauthorized use of resources is called ''computer security''. Similarly, the defense of computer networks is called ''network security''. The subversion of computers or their unauthorized use is referred to using the terms ''cyberwarfare'', ''cybercrime'', or ''security hacking'' (later shortened to ''hacking'' for further references in this article due to issues with ''hacker'', ''hacker culture'' and differences in white/grey/black 'hat' color identification). Types Below, various software implementations of Cybersecurity patterns and groups outlining ways a host syste ...
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Tracing (software)
In software engineering, tracing involves a specialized use of logging to record information about a program's execution. This information is typically used by programmers for debugging purposes, and additionally, depending on the type and detail of information contained in a trace log, by experienced system administrators or technical-support personnel and by software monitoring tools to diagnose common problems with software. Tracing is a cross-cutting concern. There is not always a clear distinction between ''tracing'' and other forms of ''logging'', except that the term ''tracing'' is almost never applied to logging that is a functional requirement of a program (therefore excluding logging of data from an external source, such as data acquisition in a high-energy physics experiment, and write-ahead logging). Logs that record program usage (such as a server log) or operating-system events primarily of interest to a system administrator (see for example ''Event Viewer'') fal ...
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Express Data Path
XDP (eXpress Data Path) is an eBPF-based high-performance data path used to send and receive network packets at high rates by bypassing most of the operating system networking stack. It is merged in the Linux kernel since version 4.8. This implementation is licensed under GPL. Large technology firms including Amazon, Google and Intel support its development. Microsoft released their free and open source implementation ''XDP for Windows'' in May 2022. It is licensed under MIT License. Data path The idea behind XDP is to add an early hook in the RX path of the kernel, and let a user supplied eBPF program decide the fate of the packet. The hook is placed in the network interface controller (NIC) driver just after the interrupt processing, and before any memory allocation needed by the network stack itself, because memory allocation can be an expensive operation. Due to this design, XDP can drop 26 million packets per second per core with commodity hardware. The eBPF program must p ...
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Packet Processing
In digital communications networks, packet processing refers to the wide variety of algorithms that are applied to a packet of data or information as it moves through the various network elements of a communications network. With the increased performance of network interfaces, there is a corresponding need for faster packet processing. There are two broad classes of packet processing algorithms that align with the standardized network subdivision of control plane and data plane. The algorithms are applied to either: :* Control information contained in a packet which is used to transfer the packet safely and efficiently from origin to destination :or :* The data content (frequently called the payload) of the packet which is used to provide some content-specific transformation or take a content-driven action. Within any network enabled device (e.g. router, switch, network element or terminal such as a computer or smartphone) it is the packet processing subsystem that manages the t ...
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Run-to-completion
Run-to-completion scheduling or nonpreemptive scheduling is a scheduling model in which each task runs until it either finishes, or explicitly yields control back to the scheduler. Run to completion systems typically have an event queue which is serviced either in strict order of admission by an event loop, or by an admission scheduler which is capable of scheduling events out of order, based on other constraints such as deadlines. Some preemptive multitasking scheduling systems behave as run-to-completion schedulers in regard to scheduling tasks at one particular process priority level, at the same time as those processes still preempt other lower priority tasks and are themselves preempted by higher priority tasks. See also * Deadline scheduling * Preemptive multitasking * Cooperative multitasking Cooperative multitasking, also known as non-preemptive multitasking, is a style of computer multitasking in which the operating system never initiates a context switch from a run ...
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Event-driven
Event driven may refer to: The term event-driven refers to a methodology that focuses on events and event dependencies. Examples include * Event-driven finite-state machine, finite-state machine where the transition from one state to another is triggered by an event or a message * Event-driven programming, a programming paradigm in which the flow of the program is determined by events, and is often characterised by a main loop, event handlers, and asynchronous programming * Event-driven architecture, a software architecture pattern promoting the production, detection, consumption of, and reaction to events * Event-driven investing, a hedge fund investment strategy that seeks to exploit pricing inefficiencies that may occur before or after a corporate event * Event-driven process chains, a type of flowchart used for business process modelling * Workflow A workflow consists of an orchestrated and repeatable pattern of activity, enabled by the systematic organization of resource ...
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