alt Hacker NewsCasey Muratori – The Root of the Root of All Evil – BSC 2026 [video]
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Terrific presentation. But I have a comment:
His dismissal of the argument Knuth makes regarding the hot loops could have been explored a bit better. I found it weird he didn’t mention the difference of types of programs of then vs now. Even today, in scientific code it is still absolutely the case a lot of the time that a huge chunk of the runtime comes from a single very very hot loop. It might be hidden in a library, but it’s there. Instead he focuses only on “program size”. Knuth samples where very small FORTRAN programs (compared to today’s standards). Today’s program are bigger but the fundamental number crunching primitive of “let’s compute stuff in a loop” remains. It’s just buried under a pile of extra cruft (data loading, parallelism, dispatching etc).
Now we just deal with a lot more programs that are of a whole different class compared to what they where doing with computers in the 70s. We have much more I/O involved. And hot loops don’t like being I/O bound.
Personally I'm quite sure this is super interesting, but I don't really have 3 hours to listen to this, even 1.5h at 2x speed is too much.
I would very much prefer something written down, so I could absorb this at my own pace. I know, gift horse, but still.
It's a common situation for many quotes of such kind. Taken out of context they loose or completely change their initial meaning.
I enjoyed this talk. It’s long, but it’s interesting and goes into a lot of “lost” history.
Do not guess. Measure, but only measure the bottlenecks that threaten the business
Will have to give this a watch after the kids go to bed. I like a lot of Casey’s views even if I don’t agree with them.
tl;dr the saying is that "premature optimisation is the root of all evil", and Casey burrows into contemporary data to show that really although the claim was 3% of the code takes up 90% of the runtime even then it was more likely 4% takes 50%.
The best thing you could take away from this lecture is something a reasonable person should take away from the original "root of all evil" saying anyway. Measure. Measure. Measure. If you aren't measuring that's not optimization it's masturbation.
Ironically in the process of measuring for a third time yesterday I tripped a bug in Bill's language for which I opened an issue. This is not the goal of measuring three times but merely a happy accident.
Along the way Casey discovers (?) that Structured Programming means just what we today call programming†, that software was a lot smaller in the days when 4096 bytes of RAM was a good entry level option and that loads of these famous people from 1970s computer science knew each other.
† And knowing about this is one reason the Structured Concurrency people want that everywhere. Very possibly there's a future where it seems silly that people once wrote programs which did not use structured concurrency.
It's premature optimization, according to the video description.
Legend
I think Casey is currently the most informed person to make a series of books or articles summarizing the history of SW Engineering, all the lessons learned and forgotten, and all the good stuff that was published and still hasn't gained traction in the practice