On September 21, 2021 12:06:35 AM UTC, Paul Wise <p...@debian.org> wrote:
>It sounds like you are talking about userland and Debian still supports
>a 32-bit userland under a 64-bit Linux kernel on 64-bit devices,
which... and i apologise, i cannot remember your name, our
person-running-CNC-lathes pointed out that the latency on context-switches,
presumably because of conversions on system calls between 64 and 32 bit and
back, is awful, and making microsecond response time barely achievable.
microsecond response... 1e6.... clock speeds 2e9... bordering on 2,000
instructions for a contextswitch and syscall, any typeconversion is apparently
too much.
> do
>these concerns also apply to the Linux kernel itself?
to a lesser extent given the relative size of the linux kernel, we may surmise
only the most extreme resource constrained scenarios would be concerned about
that, and they're likely to be using yocto, buildroot, Zephyr or other RTOS
etc. custom from-source builds.
i had forgotten about the latency issue though, and was fascinated to hear that
running CNCs is so borderline.
i wonder if x86 does so much better there due to hyperthreading.
l.
