Re: uarea swap-out

[Mindaugas Rasiukevicius <rmind%netbsd.org@localhost>]

matthew green <mrg%eterna.com.au@localhost> wrote:
> 
> i'm really curious how this affects platforms with very
> few hardware pages, like acorn26.
> 

I cannot measure that empirically, therefore CC'ing port-acorn26 and
port-acorn32 lists. There are few points regarding this:

- Merge of lwp_cache and uarea (it puts struct lwp, pcb and kstack together)
  should have positive effect i.e. it would increase the utilisation of pages.

- The criteria when LWP can be swapped-out is relatively strict i.e. there
  are already many states when it cannot, see swappable() in uvm_glue.c.

- If your machine starts swapping uareas, I think it is already quite a
  hammer, especially for machines like acorn26/32.

Newer patch removing uarea swap-out:

http://www.netbsd.org/~rmind/uarea_swapout3.diff

By the way, patch cuts ~4k from amd64 kernel size.

> 
> .mrg.

-- 
Mindaugas