Re: What to do with slow Chip/ST RAM

[email protected] wrote:

> On Wed, 11 Mar 2009, Izumi Tsutsui wrote:
> > [email protected] wrote:
> >>  	Both amiga and atari have the concept of 'fast' and 'slow' RAM.
> >>  	For a system with a reasonable amount of fast RAM using the
> >>  	slow RAM can actually slow things down, though it seems like
> >>  	a shame to waste it...
> >
> > I guess ST is on 16 bit bus and TT is on 32 bit bus on atari,
> > and both could be handled by pmap/uvm with proper priorities
> > by MI uvm(9) API. IIRC, mvme68k has some code which handles
> > slower (no cache) VME bus memory.
> 
>  	Aha, that would be the free_list param to uvm_page_physload()?
>  	Is memory allocated strictly from the freelists in ascending
>  	order?

uvm_page_physget() in sys/uvm/uvm_page.c seems to do so.

>  	So the 'slow' ram on amiga and atari is probably not 'slow enough'
>  	to be worth switching to swap, though it would be beneficial to
>  	put them on separate free lists, so fast ram is consumed first?

I think so, but currently atari passes both ST and TT ram to
uvm_page_physload() with the same free_list in pmap_bootstrap.c.

Maybe we could add some parameter which represents ST/TT
in usable_segs[] in atari_init.c.

---
Izumi Tsutsui