One of my previous jobs involved coding on a media processor. That processor had a direct-mapped cache, so code size and layout mattered. Ideally, you wanted the performance-critical code to fit in the cache and be in different cache lines to avoid thrashing.
As a concrete example, Carlos Bueno's Mature Optimization Handbook[0] describes how the HHVM team got substantial performance wins by reducing instruction cache misses in rarely executed code.
Personally I see the value in exploring the limits of what systems are capable of, and exploring ways to use them outside of the parameters for which they were designed.
I would also generally like to avoid being on-call for a system that is being pushed to its limits or used outside the parameters it was designed for.
I am very curious to hear if anyone is shipping cosmopolitan-libc/Actually-portable-executable binaries, either internally or for consumption by end users. I would love to hear more about the experience!
Not to belittle Justine's achievements, but the role of the most important software developer probably goes to the maintainer of some hugely important infrastructure project that we barely know about.
If Justine didn't optimize struct padding, binaries would be a bit larger, but software would keep working. However, if a trivial library like left-pad is gone, it triggers global chaos of such monumental proportions that it warrants its own Wikipedia article https://en.wikipedia.org/wiki/Npm_left-pad_incident
Or there might be some unsung hero responsible for fixing a year 2038 bug in a bunch of ICBMs who prevented worldwide nuclear annihilation (or who caused it, if you have a more pessimistic view of the future).
She's created a compatibility layer enabling portability of a huge amount of software between operating systems, which will enable a huge number of other developers a path into those operating systems and the hardware they are running.
