Re: CVS commit: src/sys

[Andrew Doran <ad%netbsd.org@localhost>]

On Thu, Feb 06, 2020 at 11:30:20PM +0000, Jason R Thorpe wrote:

> Modified Files:
> 	src/sys/net: if.c if.h
> 	src/sys/netinet: ip_carp.c
> 
> Log Message:
> Perform link state change processing on a work queue, rather than in a
> softint.

Thinking out loud more than anything else:

Bit concerning that we're growing a ton of kthreads in the network stack (my
test system now has something like 700 kthreads total) but I'm less worried
about that and moreso that a lot of these seem to be in the kernel RT range
and will therefore cause kernel preemptions when triggered.

For something like a link state change that's no biggie but I'm not fond of
the idea of bulk wire & protcol processing needing mi_switch() + kpreempt(). 
Way back when we made a concious decision not copy the design pattern our
sister project went with on this front.  Maybe it is the right way to go now
but I think that should also be a concious design decision.

Andrew