[hinkley]

Once upon the time I became the de facto admin for a VxWorks box because my code was to be the bottleneck on a task with a min throughput defined in the requirements and we weren't hitting the numbers. I ended up having to KVM into it and run benchmarks in vivo, which meant understanding the command line which I'd never seen before.

People were understandably concerned that we had fucked up in the feasibility phase of the project. Lots of people get themselves in trouble this way, and this was a 9 figure piece of hardware sitting idle while our app picked its nose crunching data, if we didn't finish our work on time during maintenance windows.

But I was on my longest hot streak of accurate perf estimates in my career and this one was not going to be my Icarus moment. It ended being tweaks needed from the compiler writer and from Wind River (DMA problem). I had to spend a lot of social capital on all of this, especially the Wind River conference call (which took ten minutes for them to come around to my suggestion for a fix that they shipped us in a week. After months and months of begging for a conference call).

[iscoelho]

100% on the business implications. Although a lot of engineers never have to touch it, DMA (& zero-copy) implementations are foundational to the performance of modern day computers that we sometimes take for granted.

[hinkley]

The hard drive was running so slow I exclaimed “it’s almost like this drive is running in PATA mode.”

It was. Motherboard and CPU were newer than the VxWorks version and it was running in compatibility mode. We treated it like the previous hardware revision it was backward compatible with and 30% more throughput like magic. Exactly as predicted.