> On the subject of priority levels, here is one suggestion and some notes:
> 
> 160 - 191       Interrupt (32)
> 96 - 160        Real time (64)
> 64 - 95         Kernel (32)
> 0 - 63          User (64)
> 
> o FreeBSD positions "real time" below kernel, this is the other way around.
> o FreeBSD also has the concept of idle priority levels. Is this something
>   we also want? Are multiple levels required?
> o Low really does mean low, and high means high. Traditionally the priority
>   has been "inverted".
> o It's fairly arbitrary!

i think dedicating the lowest priority (== 0) to idle lwps can save
some "if (idlelwp)".

(i'm talking about ci->ci_data.cpu_idlelwp, not freebsd's idle priorities.)

YAMAMOTO Takashi