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What’s Operating Systems Research About?
The other day at lunch I tried to explain to Suresh what operating systems research is all about, which got me thinking about this subject. As a quick glace at the OSDI 2012 program will confirm, the obvious answer “it’s about building operating systems” no longer applies, if it ever did. In fact, the trend away from…
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The Citation Telephone Game
My kids often come home from school spouting crazy “facts” they’ve learned from classmates. It seems fundamentally human to repeat stories and, in the repeating, alter them—often unintentionally. Researchers do the same thing, and just this morning I was irritated to read an entirely inaccurate citation of one of my own papers. No doubt others…
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The Hidden Cost of Compiler Bugs
I have a hypothesis that compiler bugs impose a noticeable but hard-to-measure tax on software development. I’m not talking so much about compiler crashes, although they are annoying, but more about cases where an optimization or code generation bug causes a program to incorrectly segfault or generate a wrong result. Generally, when looking at a test case…
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Core Question
[This post is about machines used by people. I realize things are different in the server room.] We had one core per socket for a long time. When multi-cores came along, dual core seemed pretty awkward: real concurrency was possible, but with speedup bounded above by two, there wasn’t much point doing anything trickier than…
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Cyber War
I recently read Richard Clarke’s Cyber War. Although I didn’t learn anything new on the technical side, that isn’t the focus of the book. Clarke’s main agenda is to build awareness of the uniquely vulnerable position that the United States finds itself in as well as proposing national policies that might lead to a more…
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It’s Time to Get Serious About Exploiting Undefined Behavior
[Note: I promise, this is almost my last post about undefined behavior for a while. Maybe just one more in the queue.] The current crop of C and C++ compilers will exploit undefined behaviors to generate efficient code (lots of examples here and here), but not consistently or well. It’s time for us to take this…
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Undefined Behavior Consequences Contest Winners
The contest that I posted the other day received some very nice entries. I decided to pick multiple winners since the best entries illustrate consequences of several kinds of undefined behavior. First, here’s the runner up, submitted by Octoploid: This program is undefined by C99, where signed left shifts must not push a 1 bit…
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Contest: Craziest Compiler Output due to Undefined Behavior
[UPDATE: Winners are here.] The C and C++ standards fail to assign a meaning to a program that overflows a signed integer or performs any of the 190+ other kinds of undefined behavior. In principle, a conforming compiler can turn such a program into a binary that posts lewd messages to Twitter and then formats…
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Parallelizing Delta Debugging
Delta debugging is a technique for taking an input to a computer program that causes the program to display a certain behavior (such as crashing) and automatically creating a smaller input that triggers the same behavior. For complex programs that typically process large inputs (compilers, web browsers, etc.) delta debugging is an important part of…
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Scooping and New Publication Models
If I come up with a great new research idea, sit on it for a couple of years, and then someone else publishes it before I do, then I got scooped. This is unfortunate but as long as the ideas were developed independently, nobody has done anything wrong. Of course, in the real world, establishing…