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David L. Mills
Personal blog · eecis.udel.edusystemsscience
David L. Mills's personal blog at eecis.udel.edu covers systems and science. Since 2010, 36 different Hacker News readers have linked it 39 times, most often “Execution in the Kingdom of Nouns (2006) [pdf]”. No feed was found, so read it on the site itself.
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39mentions?
36HN people?
2010–2025first – last linked?
Most-linked posts?
- /~amer/PEL/poc/pdf/SPDY-Fan.pdf6 people · 6 mentions · first linked 2012-02-23
- Execution in the Kingdom of Nouns (2006) [pdf]2 people · 4 mentions · first linked 2018-08-17
- LZW and GIF explained2 people · 2 mentions · first linked 2018-05-14
- A Brief History of NTP Time: Confessions of an Internet Timekeeper (2003) [pdf]2 people · 2 mentions · first linked 2012-11-23
What Hacker News says?
If someone is interested, here is the Reference and Implementation Guide of the latest NTP version (2006, was revised in 2010), written by Dave Mills: https://www.eecis.udel.edu/~mills/database/reports/ntp4/ntp4... Quite well written, in my opinion.
Comment linking /~mills/database/reports/ntp4/ntp4.pdf
on “Dave Mills has died”Submitted LZW and GIF explained as a story · 92 points
HN discussionAn "fun" use of ip addresses is in NTP. in the ntp config file, you will have stuff like this: server 127.127.1.0 # local clock or: server 127.127.20.0 minpoll 4 iburst prefer # gps clock where the "ip address" is of the form: 127.127.<clocktype>.<instance> here's a page explaining the clock types: https://www.eecis.udel.edu/~mills/ntp/html/refclock.html but basically it's a weird anachronism. I'm not sure if NTP wi…
Comment linking /~mills/ntp/html/refclock.html
on “Fun with IP address parsing”Submitted The Nanokernel [pdf] as a story · 57 points
HN discussionI'm a bit rusty, but I believe the way NTP works (at least the reference version which is commonly used) is that if a client sends too many requests in a short time, they are ignored except to reply with a "back off packet" which is called the KoD (Kiss of death) in NTP terms. Security audits have found some issues with abusing the KoD so I'm not sure if it still works like that or if it tends to be disabled. (I was…
Comment linking /~mills/ntp/html/rate.html
on “TP-Link firmware sends six DNS requests and one NTP query every 5 seconds”Submitted A Brief History of NTP Time: Confessions of an Internet Timekeeper (2003) [pdf] as a story · 14 points
HN discussionOf the various internet .+P, NTP is one I never learned about as a student, so now I'm looking at its web page [1] by its creator David L. Mills (1938-2024). I've found one video of him giving a retrospective of his extensive internet work; he talks about NTP at 34:51 [2] and later at 56:26 [3]. [1] https://www.eecis.udel.edu/~mills/ntp.html [2] https://youtu.be/08jBmCvxkv4?si=WXJCV_v0qlZQK3m4&t=2092 [3] https://you…
Comment linking /~mills/ntp.html
on “NTP at NIST Boulder Has Lost Power”Submitted Text Chunking using NLTK as a story · 6 points
HN discussionNTP does store context for a limited number of clients (600 by default). https://www.eecis.udel.edu/~mills/ntp/html/miscopt.html
Comment linking /~mills/ntp/html/miscopt.html
on “Excessive load on NTP servers”Submitted Timekeeping in the Interplanetary Internet as a story · 5 points
HN discussionNTP has rate limiting built into the protocol ( https://www.eecis.udel.edu/~mills/ntp/html/accopt.html ), but Snapchat appear to be using a large list of servers. Also, NTP runs on UDP rather than TCP, and it only requires one packet from each party to exchange time, so it's harder to rate-limit it without making your server unreliable.
Comment linking /~mills/ntp/html/accopt.html
on “Excessive load on NTP servers”Submitted LZW and GIF explained as a story · 3 points
HN discussion[author] > I wish he'd explained somewhere how they leapt to examining virtualized NTP clients... I had a hunch [wrongly] that the traffic was caused by a particular operating system. I didn't have enough machines to run the tests on bare-metal, so I virtualized them. And I suspected that virtualization would provide a worst-case scenario (the virtualized clocks would be jittery). My big surprise was that Windows wa…
Comment linking /~mills/ntp/html/rate.html
on “Why is my NTP server costing $500 per year? Part 1 (2014)”Submitted Confessions of an Internet Timekeeper as a story · 3 points
HN discussionIEEE 1588 (Precision Time Protocol) has already solved this problem for every use case that matters and offers microsecond precision. https://www.eecis.udel.edu/~mills/ptp.html PTP takes advantage of special Ethernet switches and other devices which can decode or manipulate the time tags in hardware because yes your switches add latency. This just sounds like more horseshit out of SV. I applaud them for convincing s…
Comment linking /~mills/ptp.html
on “Clockwork raises $21M to keep server clocks in sync”Submitted A Brief History of NTP Time: Confessions of an Internet Timekeeper [pdf] as a story · 2 points
HN discussionI believe Patrick already well explained why this the binary representation is useful, so I won't bother addressing that. I'd like to comment on your statement on the header compression dictionary. Firstly, your statement is only true for the initial header compression dictionary. Most of the improvement is achieved strictly through the use of compression at all, with very marginal gains from different compression a…
Comment linking /~amer/PEL/poc/pdf/SPDY-Fan.pdf
on “Speeding up HTTP with minimal protocol changes”Submitted Execution in the Kingdom of Nouns (2006) [pdf] as a story · 2 points
HN discussionWell, quoting from: http://www.eecis.udel.edu/~mills/ntp.html " Used in the Internet of today with computers ranging from personal workstations to supercomputers, NTP provides accuracies generally in the range of a millisecond in LANs and up to a few tens of milliseconds in the global Internet " But this is news to me, interesting: "When kernel support for precision timing signals, such as a pulse-per-second (PPS) s…
Comment linking /~mills/ntp.html
on “Twitter Announces "Snowflake" for Unique Tweet IDs”Submitted Execution in the Kingdom of Nouns [pdf] as a story · 1 points
HN discussionLooks like I was wrong: https://www.eecis.udel.edu/~mills/leap.html
Comment linking /~mills/leap.html
on “Making every (leap) second count with our new public NTP servers”Submitted Features that you most probably didn’t know your Microprocessor had(.ppt file) as a story · 1 points
HN discussion> This is what boggles my mind about Spdy, the dissonance. On the one hand Spdy is great because it does a bunch of requests on the same TCP connection, but on the other hand Spdy is great because it saves 100 bytes per connection and that's a big deal because there are going to be so many connections made? It doesn't make sense. Adaptability: SPDY works well for both cases, rather than only picking one case and opt…
Comment linking /~amer/PEL/poc/pdf/SPDY-Fan.pdf
on “SPDY Protocol (draft 3) submitted to IETF”Submitted Combining Physics and Computer Science as a story · 1 points
HN discussion> Browsers won't keep SPDY connections open forever in the hopes of someday reusing them; the "initial connection" case will happen quite frequently in a normal browsing session. This is what boggles my mind about Spdy, the dissonance. On the one hand Spdy is great because it does a bunch of requests on the same TCP connection, but on the other hand Spdy is great because it saves 100 bytes per connection and that's…
Comment linking /~amer/PEL/poc/pdf/SPDY-Fan.pdf
on “SPDY Protocol (draft 3) submitted to IETF”http://www.chromium.org/spdy - contains some great and in-depth research motivating SPDY. Original whitepaper: http://www.chromium.org/spdy/spdy-whitepaper Here's a good tech talk to checkout as well: http://www.youtube.com/watch?v=TNBkxA313kk Draft 3 has also updated the dictionary, here's the research paper motivating the change: http://www.eecis.udel.edu/~amer/PEL/poc/pdf/SPDY-Fan.pdf
Comment linking /~amer/PEL/poc/pdf/SPDY-Fan.pdf
on “SPDY Protocol (draft 3) submitted to IETF”I have a (mostly working, neglected) implementation of SPDYv2 in erlang (github.com/RJ/erlang-spdy). I've been following the mailing list about the v3 spec. Notable differences if you are updating a spdy library: * various fields changed size * compression dictionary [1] for headers block updated * a few things clarified where spec was ambiguous * CREDENTIAL frame, so multiple ssl certs can be used on one connection…
Comment linking /~amer/PEL/poc/pdf/SPDY-Fan.pdf
on “SPDY Protocol (draft 3) submitted to IETF”> Then, in the late 1980s--spurred by the early work of Judea Pearl, a professor of computer science at UCLA, and breakthrough mathematical equations by Danish researchers--AI researchers discovered that Bayesian networks offered an efficient way to deal with the lack or ambiguity of information that has hampered previous systems. The "mathematical equations by Danish researchers", for those interested, are most lik…
Comment linking /~shatkay/Course/papers/Lauritzen1988.pdf
on “Improbable Inspiration: Bayesian Networks (1996)”I highly doubt that. I have a FingerWorks Touchstream LP that (while I don't use it anymore) was performing the same exact gestures we all recognize as "swipes" on capacitive touchscreen phones/tablets. As evidence I point you to the founder's dissertation on the topic from 1999: http://www.eecis.udel.edu/~westerma/main.pdf The only difference between how it worked on a Touchstream LP and a modern capacitive touchsc…
Comment linking /~westerma/main.pdf
on “Apple Patent on Touch Typing, Multitouch Upheld; Allows Ban on Most Androids”A good portion of the size difference (though certainly not all) is that ntp.org's ntpd has a lot of drivers to interface with physical devices [1], while OpenNTPD doesn't. If you don't own the physical devices, the LoC in the drivers are kind of a wash: they're not useful to you, but you also won't be running them. A stripped-down NTP-client-only build option would be nicer, though. PHK's suite of ntpd replacement…
Comment linking /~mills/ntp/html/refclock.html
on “OpenNTPD 5.7p1 Released”
