How does realtime enforce precision and not latency? I was referring to hard realtime.

And wow, so I wasn't too far off the mark. FPGAs and exotic networking. Huh.

I remember reading a story about a trading floor running on SQL Server, which was doing continuous throughput of 6000 queries/second. I didn't know enough at the time to discern what percentage of that was writes, but I think the point may have been that it was all of it. This was quite a few years ago. So perhaps Windows isn't actually the slowe{st,r} system out there for certain tasks.

As I've always understood (but I'm no RTOS expert) is that RTOS does not guarantee LOWER latency. It guarantees A latency.

But again: not an RTOS expert. We had a lab that would constantly test configurations of hardware and software. And I remember them finding RTOS not being helpful.

That's right, real-time does not mean real-fast. In a hard real-time system, there is a deterministic worst-case bound for response times. "Real fast" CPUs, like the latest and greatest Intel CPUs, are actually pretty difficult to get deterministic bounds on. There are factors like unpreventable SMI events, possibility of L1/L2/L3 cache misses, etc. Often systems that need to be really deterministic, like say an engine controller in a car, run on simple CPUs like the Cortex-R series from ARM.

> "Real fast" CPUs, like the latest and greatest Intel CPUs, are actually pretty difficult to get deterministic bounds on. There are factors like unpreventable SMI events, possibility of L1/L2/L3 cache misses, etc.

Oh yeah. I remember reading something along the same lines about x86 a while back. I guess it didn't really go in properly, heh. Thanks

I'm reminded of the "x86 is high level" thing: https://news.ycombinator.com/item?id=9264195

Also, I think the iPhone 6's NVMe apparently uses a Cortex-R: https://ramtin-amin.fr/#nvmepcie