Re: Time sharing for interrupt threads

From: John Baldwin <>
Date: Thu, 23 Jun 2022 21:56:06 UTC
On 5/4/22 2:48 PM, John Baldwin wrote:
> The changes to implement this can be found on the swi_refactor
> branch here:

I have extended this branch a bit further.  It now supports time sharing on
4BSD as well (mostly just for completeness).  I've also collapsed the
ithread priorities down to just 4 effective values merging all hardware
ithreads into a PI_HARDWARE and all SWIs to PI_SOFT.  I think I might have
moved softclock back to PI_SOFT.

I also shuffled the other priority ranges around to move the now-unused
priority values down to the user range so that CPU schedulers have a bit
more precision/granularity for user processes.

Drew did test this under a production loader and did not find any regressions.
I would still appreciate some review on the idea though?

I have not done any of the work to try to simplify interrupt handling in

John Baldwin