> It was said that ‘‘you really can’t appreciate troff (and runoff and scribe) unless you do all of your document preparation on a fixed width font 24 line by 80 column terminal’’. ‘‘Challenge accepted’’ I said to myself.
But the title is a misleading: this was a modern v7 port with some extra amenities. It's hard to appreciate just how primitive these early systems were without using them in their original form.
Speaking of which, here's some people attempting to get the original PDP-7 unix (i.e. pre-v1) running agin. There aren't scans for all of the source code though. Most importantly the shell is missing. So they had to rewrite one themselves.
A story full of "I didn't realize it was impossible, so I went ahead and did it" moments.
A bit like a a very compressed "Soul of a New Machine". I've been reading a lot of old timesharing papers, most of them are dreadfully boring even for me. (Don't ask why I've been reading that stuff...) But this particular kind of personal story of the creation of influential but totally forgotten technology is like catnip.
Designing a timeout system for a Python IO API. (Feels like a very Common Lisp-y solution to me, with the hidden global state with enforced dynamic extent).
> One tiny, ugly bug. Fifteen years. Full system compromise.
A step-by-step walk through an OS X local vulnerability (and it's a lot of steps). Another of those writeups that make you wonder how anyone ever manages to get from concept to an actual exploit.
Oh, ok... So that's what the Linux page table changes discussed a couple of weeks ago were about. This looks really bad. It seems amazing that nobody found it before now, but on the other hand at least the exploits for Spectre look really hard to pull off (needing to e.g. reverse engineer the branch predictor, so that it can be trained to expose one bit of data...) So maybe a lot of people had tried, and nobody just managed to do it.
Now that's a much more approachable speculative execution bug!
I like this paper. It doesn't just naively measure TCP vs QUIC, but also tries to map the results to the underlying mechanisms. But "ouch" on the fairness tests.
The dangers of just throwing garbage data at a machine learning model. (And in a medical setting, even!)
What happens if you switch the example code of a difficult systems programming course from gnarly '80s style C to modern C? Apparently the students are able to implement much more complex memory allocator features.
(They also changed the malloc test suite at the same time. But it seems hard to believe that the tests would have a major effect here).
> The correct solution to the “integer printing is too slow” problem is simple: don’t do that.
> However, once you find yourself in this bad spot, it’s trivial to do better than generic libc conversion code. This makes it a dangerously fun problem in a way… especially given that the data distribution can matter so much.
Paul Khuong on fast integer -> decimal string conversions.
Reporting on some mysterious ongoing Linux development. Just how bad a security bug does this have to be, if they're willing to take a 5% system-wide performance hit to work around it?
Insane retro-hardware maintenance.
A funny story about extreme capitalism in an MMO setting, the kind you'd expect to be a digression in a good Neal Stephenson novel. I have no idea whether this is actually true or not, but it probable doesn't matter either way :)
Input-to-display latency measurements for 40 years of computers.
How the voxel physics engine of Roblox works.
And then for physics of a different kind... Basically modeling crowds of people as a fluid dynamics system.
> Developing and testing a virtual version of Unix on OS/32 has practical advantages. There was no need for exclusive use of the machine; [...]. And the OS/32 interactive debugger was available for breakingpoint and single-stepping through the Unix kernel just like any other program.
A port of Unix v6, from before it was really meant to be portable. A lovely systems programming story.
A very amusing system programmer's lament.
Ignore the title. It's not actually a rant about Skype sucking, but a really cool article series on someone writing their own codec + packet-loss tolerant UDP networking for a prototype video conferencing app.
Micro-optimizing lockless message passing between threads.
Then use this to replace locks on data structures. Instead of data structures being shared, they're owned by a specific server process. If a client needs to operate on data structure, it asks the server to do it instead. Assuming heavy contention, this'll be much faster since fewer cache coherency roundtrips are required.
(Obviously not widely applicable, due to the scheme requiring busylooping to work well.)
This'll go into the hall of fame of great debugging stories.
The PDP-I 1 was designed to be a small computer, yet its design has been successfully extended to high-performance models. This paper recollects the experience of designing the PDP-I I, commenting on its success from the point of view of its goals, its use of technology, and on the people who designed, built and marketed it.
A lovely mid-life postmortem for the PDP-11.
(Via Dave Cheney; a useful companion piece putting the paper in the historical context, but not a replacement for reading the original.)
Could you replace B-Tree/hash/bloom filter database indexes with machine learning models? The depressing answer appears to be that it's viable. I thought the systems programmer was going to be the last job in the world!
But assuming this is the state of the art (rather than a more typical "this is what we were deploying 5 years ago" Google paper), it's not quite practical yet. CPUs aren't efficient enough, communication overhead with GPUs/TPUs too large. But that's an architecture problem that will get solved.
Creating a bogus @google.com address using one bug, and then getting rights to access the details of all (most?) bugs in the system.
There's a funny thing where for most software vulnerabilities a writeup like this can explain exactly what happened why. But then for web-based services all you see is a bug that looks totally braindead. It's user accounts! how hard can that possibly be?
I work on stuff related to security of account systems at the moment; turns out that just like in every other area of modern computing, it's incredibly complicated.
You've forgot the PIN and passphrase of your hardware bitcoin wallet. Must be out of luck, those things can't possibly have trivial vulnerabilities. I mean, surely those sophisticated cryptocurrency enthusiasts would be able to spot the snakeoil a mile away. Oh... No?
Rewriting the Xen control plane to optimize the boot time of thousands of tiny VMs. Benchmarked against Docker, which seems just absurdly bad at this one.
(Not impressed by the numbers outside of booting with regard to "lightness". E.g. the throughput and scaling numbers for the personal firewall application are just miserable.)
It's possible for multiple houses (e.g. in different cities) to have the same street name and number. What's the closest pair of such "twins" in the UK?
I truly appreciate the dedication that went into researching this bit of trivia.
Why POSIX filesystem semantics aren't a good fit for large scale systems. (The funny thing is that it never occurred to me that anyone would use POSIX APIs in a modern distributed context. But apparently in supercomputing they do).