Matthew Dillon (born 1966) is an American

software engineer Software engineering is a systematic engineering approach to software development. A software engineer is a person who applies the principles of software engineering to design, develop, maintain, test, and evaluate computer software. The term ''p ...

known for

Amiga Amiga is a family of personal computers introduced by Commodore in 1985. The original model is one of a number of mid-1980s computers with 16- or 32-bit processors, 256 KB or more of RAM, mouse-based GUIs, and significantly improved graphi ...

software, contributions to

FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ...

and for starting and leading the

DragonFly BSD DragonFly BSD is a free and open-source Unix-like operating system forked from FreeBSD 4.8. Matthew Dillon, an Amiga developer in the late 1980s and early 1990s and FreeBSD developer between 1994 and 2003, began working on DragonFly BSD in Ju ...

project since 2003.

Biography

Dillon studied

electronic engineering Electronics engineering is a sub-discipline of electrical engineering which emerged in the early 20th century and is distinguished by the additional use of active components such as semiconductor devices to amplify and control electric current ...

and

computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, practical discipli ...

at the

University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant u ...

, where he first became involved with

BSD The Berkeley Software Distribution or Berkeley Standard Distribution (BSD) is a discontinued operating system based on Research Unix, developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berk ...

in 1985. He also became known for his

programming, his C compiler DICE and his work on the

Linux kernel The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ope ...

. He founded and worked at Best Internet from 1994 until 1997, contributing to

in that time. His "Diablo" internet news transit program was very popular with many ISPs. In 1997, Dillon gained commit access to the FreeBSD code and heavily contributed to the

virtual memory In computing, virtual memory, or virtual storage is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very l ...

subsystem, amongst other contributions. Concerned with problems he saw in the direction FreeBSD 5.x was headed in regards to concurrency, and coupled with the fact that Dillon's access to the FreeBSD source code repository was revoked due to a falling-out with other FreeBSD developers, he started the

project in 2003, implementing the SMP model using light-weight kernel threads. The DragonFly project also led to the development of a new

userspace A modern computer operating system usually segregates virtual memory into user space and kernel space. Primarily, this separation serves to provide memory protection and hardware protection from malicious or errant software behaviour. Kernel ...

kernel

virtualisation In computing, virtualization or virtualisation (sometimes abbreviated v12n, a numeronym) is the act of creating a virtual (rather than actual) version of something at the same abstraction level, including virtual computer hardware platforms, sto ...

technique in 2006, called

Virtual Kernel Virtual may refer to: * Virtual (horse), a thoroughbred racehorse * Virtual channel, a channel designation which differs from that of the actual radio channel (or range of frequencies) on which the signal travels * Virtual function, a programming ...

, originally to ease the development and testing of subsequent kernel-level features; a new

file system In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one larg ...

, called

HAMMER A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nails into wood, to shape metal (as w ...

, which he created using

B-tree In computer science, a B-tree is a self-balancing tree data structure that maintains sorted data and allows searches, sequential access, insertions, and deletions in logarithmic time. The B-tree generalizes the binary search tree, allowing for n ...

s; HAMMER was declared production-ready with DragonFly 2.2 in 2009; and, subsequently,

HAMMER2 HAMMER2 is a successor to the HAMMER filesystem, redesigned from the ground up to support enhanced clustering. HAMMER2 supports online and batched deduplication, snapshots, directory entry indexing, multiple mountable filesystem roots, mounta ...

, declared stable in 2018 with DragonFly 5.2. Most recently, Dillon has gotten a number of headlines around CPU

errata An erratum or corrigendum (plurals: errata, corrigenda) (comes from la, errata corrige) is a correction of a published text. As a general rule, publishers issue an erratum for a production error (i.e., an error introduced during the publishing pro ...

. In 2007, this was after

Theo de Raadt Theo de Raadt (; ; born May 19, 1968) is a South African-born software engineer who lives in Calgary, Alberta, Canada. He is the founder and leader of the OpenBSD and OpenSSH projects and was also a founding member of NetBSD. In 2004, De Raadt wo ...

OpenBSD OpenBSD is a security-focused, free and open-source, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by forking NetBSD 1.0. According to the website, the OpenBSD project em ...

raised the alarm around the seriousness of some of the errata for

Intel Core 2 Intel Core 2 is the processor family encompassing a range of Intel's consumer 64-bit x86-64 single-, dual-, and quad-core microprocessors based on the Core microarchitecture. The single- and dual-core models are single-die, whereas the quad-core ...

family of CPUs. Dillon has independently evaluated Intel's errata, and did an overview of

Intel Core Intel Core is a line of streamlined midrange consumer, workstation and enthusiast computer central processing units (CPUs) marketed by Intel Corporation. These processors displaced the existing mid- to high-end Pentium processors at the time ...

errata as well, suggesting that several of them were so serious as to warrant avoiding any processor where the issues remain unfixed. Dillon has since been a fan of

AMD Advanced Micro Devices, Inc. (AMD) is an American multinational semiconductor company based in Santa Clara, California, that develops computer processors and related technologies for business and consumer markets. While it initially manufactur ...

processors, and, subsequently in 2012, he has discovered a brand-new deficiency in some

processors for which no existing erratum existed at the time. Dillon continued his work around CPU issues as late as 2018, presenting solutions to tackle the latest security vulnerabilities like

Meltdown Meltdown may refer to: Science and technology * Nuclear meltdown, a severe nuclear reactor accident * Meltdown (security vulnerability), affecting computer processors * Mutational meltdown, in population genetics Arts and entertainment Music * Me ...

, some of which have been subsequently adopted by

as well. Dillon was a frequent guest on bsdtalk during the runtime of the show, and was interviewed several times for

KernelTrap KernelTrap was a computing news website which covered topics related to the development of free and open source operating system kernels, and especially, the Linux kernel. News stories usually consisted of a summary of a recent discussion from a ...

References

External links

Matt Dillon home page

fro
SlashNet

OSNews interview
(March 13, 2004) {{DEFAULTSORT:Dillon, Matthew 1966 births Living people People from San Francisco University of California, Berkeley alumni American computer programmers Amiga people BSD people DragonFly BSD FreeBSD people Free software programmers Kernel programmers