Andrew Doran <ad@netbsd.org> wrote:
> o FreeBSD positions "real time" below kernel, this is the other way around.
Well, it would be POSIX defined real-time: SCHED_FIFO and SCHED_RR. I would
also like to implement SCHED_RR2 (from HP-UX), which would be the same as
traditional SCHED_RR, just with time-slicing.

> o FreeBSD also has the concept of idle priority levels. Is this something
>   we also want? Are multiple levels required?
IMHO, having the idle LWPs done by dispatcher is a benefit.

> o Low really does mean low, and high means high. Traditionally the priority
>   has been "inverted".
One would need to precisely review all >, < changes :)

As Matt already wrote - it would be good to have a high priority levels for
kernel threads (it would be specific threads, thought). You have proposed 32
priority levels for interrupts, and as we know, not all architectures would
need so many levels. Hence, I don't know the requrements of those
architectures which would use all 32 levels and I am not sure if it would be
the sane thing, but maybe we could share the 160-167 (8 levels - I don't
think would need more) range for those specific threads?

Another question is - how we would change and use PSWP..PUSER constants after
this priority model change?

> Comments?
In essence - very great!

-- 
Best regards,
Mindaugas
www.NetBSD.org