Matthew Dillon
Matthew Dillon (DragonFly BSD leader) on bicycle with bicycle helmet--2008-08.jpeg
Matthew Dillon on bicycle with bicycle helmet, August 2008
Born (1966-07-01) 1 July 1966 (age 56)[1]
Alma materUniversity of California, Berkeley
OccupationSoftware engineer
Known forAmiga DICE,[2][3] DME;[4] FreeBSD, DragonFly BSD, HAMMER

Matthew Dillon (born 1966) is an American software engineer known for Amiga software,[3] contributions to FreeBSD and for starting and leading the DragonFly BSD project since 2003.[3][5][6][7]


Dillon studied electronic engineering and computer science at the University of California, Berkeley, where he first became involved with BSD in 1985. He also became known for his Amiga programming,[3] his C compiler DICE[2] and his work on the Linux kernel.[8] He founded and worked at Best Internet from 1994 until 1997, contributing to FreeBSD in that time.[9] 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 subsystem,[10] amongst other contributions.

Concerned with problems he saw in the direction FreeBSD 5.x was headed in regards to concurrency,[10] and coupled with the fact that Dillon's access to the FreeBSD source code repository was revoked due to a falling-out with other FreeBSD developers, he started the DragonFly BSD project in 2003, implementing the SMP model using light-weight kernel threads.[3][11] The DragonFly project also led to the development of a new userspace kernel virtualisation technique in 2006, called Virtual Kernel,[3][12] originally to ease the development and testing of subsequent kernel-level features;[13] a new file system, called HAMMER, which he created using B-trees; HAMMER was declared production-ready with DragonFly 2.2 in 2009;[12] and, subsequently, HAMMER2, declared stable in 2018 with DragonFly 5.2.

Most recently, Dillon has gotten a number of headlines around CPU errata. In 2007, this was after Theo de Raadt of OpenBSD raised the alarm around the seriousness of some of the errata for Intel Core 2 family of CPUs.[14] Dillon has independently evaluated Intel's errata, and did an overview of Intel Core errata as well, suggesting that several of them were so serious as to warrant avoiding any processor where the issues remain unfixed.[14] Dillon has since been a fan of AMD processors, and, subsequently in 2012, he has discovered a brand-new deficiency in some AMD processors for which no existing erratum existed at the time.[15] Dillon continued his work around CPU issues as late as 2018, presenting solutions to tackle the latest security vulnerabilities like Meltdown, some of which have been subsequently adopted by OpenBSD as well.[16]

Dillon was a frequent guest on bsdtalk during the runtime of the show,[17] and was interviewed several times for KernelTrap.[5][6]


  1. ^ a b "usr.bin/calendar/calendars/calendar.freebsd". Super User's BSD Cross Reference. FreeBSD. 2019-02-09. Retrieved 2019-03-02.
  2. ^ a b "Matt Dillon: Where has he gone?". Newsgroupcomp.sys.amiga.programmer. 1992-11-05. Usenet: Retrieved 2019-03-02.
  3. ^ a b c d e f David Chisnall (2007-06-15). "DragonFly BSD: UNIX for Clusters?". InformIT. Prentice Hall Professional. Retrieved 2019-03-06.
  4. ^ "Happy birthday, Amiga: The 'other' home computer turns 30". The Register. 2015-07-24. Retrieved 2019-03-02. I loved Matt Dillon's editor DME, did anyone else come across that ?
  5. ^ a b Jeremy Andrews (2002-01-02). "Interview: Matthew Dillon". KernelTrap. Archived from the original on 2012-02-07. Retrieved 2019-03-03.
  6. ^ a b Jeremy Andrews (2007-08-06). "Interview: Matthew Dillon". KernelTrap. Archived from the original on 2012-02-07. Retrieved 2019-03-03.
  7. ^ "team". DragonFly BSD. 2018-05-24. Archived from the original on 2018-11-18. Retrieved 2019-03-02.
  8. ^ Matus Telgarsky (2004), "Conference Reports, USENIX Annual Technical Conference (USENIX '04), UseBSD SIG, Panel: The State of the BSD Projects" (PDF), ;login:, USENIX (published October 2004), 29 (5): 54–55, ISSN 1044-6397, Already a veteran hacker (contributor to Linux and FreeBSD, among many other projects), …
  9. ^ Greg Kulosa (1998-09-15). "BayLISA meeting: Unix on Intel: Implementing Reliable Production Systems". sage-members@ (Mailing list). USENIX. Retrieved 2019-04-12. The panelists are: BSD/OS, Paul Vixie [Internet Software Consortium founder]; FreeBSD, Matt Dillon [Systems Architect at Best Internet]; …
  10. ^ a b Federico Biancuzzi (2004-07-08). "Behind DragonFly BSD". O'Reilly Media. Archived from the original on 2011-05-13. Retrieved 2019-03-02.
  11. ^ David Chisnall (2012). "Why Go?". The Go Programming Language Phrasebook (1st ed.). Addison-Wesley Professional. p. 5. ISBN 978-0-321-81714-3. In creating DragonFly BSD, Matt Dillon observed that there was no point in creating an N:M threading model—where N userspace threads are multiplexed on top of M kernel threads—because C code that uses more than a handful of threads is very rare.
  12. ^ a b Koen Vervloesem (2010-04-21). "DragonFly BSD 2.6: towards a free clustering operating system". Retrieved 2019-03-07.
  13. ^ Jeremy C. Reed, ed. (2007-02-10). "Answers from Matt Dillon about DragonFly's virtual kernel". BSD Newsletter .com. Reed Media .net. Archived from the original on 2007-02-24.
  14. ^ a b Constantine A. Murenin (2007-07-03). "Matthew Dillon об ошибках Intel Core и Core 2" (in Russian). Retrieved 2019-03-02.
  15. ^ "DragonFly BSD developer stung by Opteron bug". The Register. 2012-03-07. Retrieved 2019-03-02.
  16. ^ "OpenBSD releases Meltdown patch". The Register. 2018-02-23. Retrieved 2019-03-02. Part of the OpenBSD solution used the approach employed by Matthew Dillon in his DragonFly BSD – the per-CPU page layout aspect.
  17. ^ "bsdtalk: DragonFlyBSD with Matthew Dillon". bsdtalk. 2014-11-19. Retrieved 2019-03-02.