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Benchmarking Short Codes on Modern Processors
Around 15 years ago, as a newish graduate student, I got access to a Pentium-based Linux machine. One of the coolest things about this machine was the new RDTSC instruction that measured the number of clock ticks since the processor had been reset. This could be used to directly observe cache misses, branch mispredictions, and…
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A Quick Update to Comparing Compiler Optimizations
Saturday’s post on Comparing Compiler Optimizations featured some work done by my student Yang Chen. Since then: There has been some discussion of these problems on the GCC mailing list; some of the problems are already in the Bugzilla and a new PR was filed. A patch fixing the problem is already available! On Sunday…
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Sometimes the Name Is the Contribution
Every now and then I read or re-read a famous, influential paper and realize (or at least suspect strongly) that it did not — at the time it was published — contain any new ideas. My guess is that a paper like this can become highly cited for one or more of the following reasons:…
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Comparing Compiler Optimizations
[Update from Dec 14: Some of these problems have already been fixed! Details here.] [This is a guest post by my grad student Yang Chen, describing one of the projects he’s been working on lately. I elaborated on some of Yang’s points, edited, and did some formatting for WordPress.] Our goal is to help C…
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Interviewing PhD Students
Although I work with a great collection of students, I’ve come to realize that my selection of students is based too much on luck and not enough on my skill in evaluating them. Therefore, I have a serious question for the professors out there, and particularly for the computer science professors in systems-related areas: Given…
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Wanted: Invariant-Based Synchronization
Although a significant fraction of the programming languages community works on detecting race conditions in multi-threaded software, I haven’t been able to get very excited about this. Certainly race-free programs have some nice properties, but race freedom is neither a necessary nor sufficient condition for concurrency correctness. This research area doesn’t feel to me like…
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Wanted: One RSS Feed Per Conference
I attend a few computer science conferences each year, and look closely at the proceedings for another half dozen. I know how to deal with these conferences. On the other hand, the conferences that give me trouble are the next 25 or so that I’m passingly interested in, that probably each contain 1-2 papers per…
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Staying Sane in Academia
This is a quick followup to this post from the other day. Here I’m going to list a few of the strategies I’ve developed for keeping my job from driving me crazy. Find places to work: home, the library, the coffee shop, whatever. Although new professors are often able to get work done in the…
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Reviewers Get Worse Over Time
This is a depressing paper. The study shows that: 92% of peer reviewers deteriorated during 14 years of study in the quality and usefulness of their reviews (as judged by editors at the time of decision) The quality of reviews that I write has definitely decreased over the 12 or so years that I’ve been…
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Computer Systems Evaluation Mistake #1
Tonight I wrote this in a paper review: The results section of this paper contains what is probably the most elementary and most annoying flaw that could possibly plague a computer systems paper. All of the numbers are relative and we’re never told the absolute values. It’s great that you can achieve a 30% reduction…