4 ms·

What do you even mean by "predictable latencies"? Afaik this needs an RTOS.

• bayindirh 3y ago
  An RTOS defines a stricter latency envelope than a mainframe, almost into "deterministic latency" range. For example, you can say "this operation will take at most 3ms" in an RTOS, and it'll never exceed that number. If you're running on a fixed-frequency system, you can even say that I expect an answer in 2.8ms all the time, every time. In a mainframe this is a bit relaxed. You can say that latency is <3ms 99% of the time, <3.1ms in 99.999% of the time and <3.5ms in 100% of the time. IOW, you never think/say "somebody is running a heavy load on the host, and I also slowed down because of them".
  • jupp0r 3y ago
    How is the mainframe's 100% number different from the upper boundary that RTOSes offer? It's not 100%, is it?
    • bayindirh 3y ago
      What I tried to say is, a mainframe might answer late, but rarely, and very slightly. a RTOS doesn't deviate from that number in either direction. It's neither early nor late. Some RTOS even doesn't consider late answers as acceptable.
      • jupp0r 3y ago
        Yeah exactly. My arm64 Linux box also might answer late, but rarely.
        • bayindirh 3y ago
          That's true, but that jitter envelope gets bigger as the load increases. For a mainframe this jitter envelope is much narrower, and in a competent RTOS, that's basically 0.