11 ms·

It's already being merged; PREEMPT_RT got merged last year. We're close to the endgame on that front. There are some performance tradeoffs to using an RT kerne

It's already being merged; PREEMPT_RT got merged last year. We're close to the endgame on that front. There are some performance tradeoffs to using an RT kernel; you trade some throughput for determinism. That said, I've been running RT on my desktop most of the time for years and never had any issues.

pabs3 5y ago
After all the patches are merged, will there be work on making PREEMPT_RT a boot-time or run-time choice rather than build-time? Why did you choose RT for your desktop?
- op00to 5y ago
  Id consider RT if I was serious about audio.
- marcan_42 5y ago
  I do audio stuff :)
  - justaj 5y ago
    And luckily _much_ more! (I'm deeply grateful for your contributions btw)
- chippiewill 5y ago
  > will there be work on making PREEMPT_RT a boot-time or run-time choice rather than build-time? Given the performance critical nature of how this changes things I personally think it's unlikely. It does stuff like change the way spinlocks work in the Kernel which would be not only difficult, but expensive without recompilation. The best I think you'll get is a boot-time option to switch between pre-compiled kernels. That being said, most of the RT Linux patches over the years are actually compiled in all the time anyway so a lot of these improvements have been incorporated for a long time.
  - marcan_42 5y ago
    It's not impossible; Linux already has a mechanism for this (alternatives, static keys), which allows patching code at runtime. It is used precisely for this kind of thing, where you don't want the performance impact of branching every time to decide what code path to use. However, while it can practically eliminate code overhead, it can't eliminate data overhead. I'm guessing the RT stuff does add overhead to data structures, and alternatives wouldn't fix that.

11 ms·

It's already being merged; PREEMPT_RT got merged last year. We're close to the endgame on that front. There are some performance tradeoffs to using an RT kerne

by marcan_42 5y ago

pabs3 5y ago
After all the patches are merged, will there be work on making PREEMPT_RT a boot-time or run-time choice rather than build-time? Why did you choose RT for your desktop?
- op00to 5y ago
  Id consider RT if I was serious about audio.
- marcan_42 5y ago
  I do audio stuff :)
  - justaj 5y ago
    And luckily _much_ more! (I'm deeply grateful for your contributions btw)
- chippiewill 5y ago
  > will there be work on making PREEMPT_RT a boot-time or run-time choice rather than build-time? Given the performance critical nature of how this changes things I personally think it's unlikely. It does stuff like change the way spinlocks work in the Kernel which would be not only difficult, but expensive without recompilation. The best I think you'll get is a boot-time option to switch between pre-compiled kernels. That being said, most of the RT Linux patches over the years are actually compiled in all the time anyway so a lot of these improvements have been incorporated for a long time.
  - marcan_42 5y ago
    It's not impossible; Linux already has a mechanism for this (alternatives, static keys), which allows patching code at runtime. It is used precisely for this kind of thing, where you don't want the performance impact of branching every time to decide what code path to use. However, while it can practically eliminate code overhead, it can't eliminate data overhead. I'm guessing the RT stuff does add overhead to data structures, and alternatives wouldn't fix that.