Re: fix swapping on 8xx?

[Tom Rini <trini@kernel.crashing.org>]

On Tue, Nov 08, 2005 at 01:59:26PM +0200, David Jander wrote:
> On Tuesday 08 November 2005 01:55, Dan Malek wrote:
> > On Nov 7, 2005, at 10:10 AM, Marcelo Tosatti wrote:
> > > The following is an attempt to fix swapping on 8xx by not touching
> > > _PAGE_ACCESSED bit if the page is not present.
> >
> > Ugh ....  I suppose.  I hate assembler code macros .......
> > Somehow, "swapping" and "8xx" just don't belong together.
> 
> Well, at least it sounds ugly together, but it is also at least conceiveable. 
> There seem to be people who use PCMCIA for an IDE interface, so swapping may 
> become desireable in some cases.

I think Dan might be in the camp that says a properly designed embedded
system won't need to swap.  And when I hear about how people do try and
swap on systems like this, I really start agreeing.  Maybe we could make
8xx just select SWAP=n? :)

> > I'm tempted to add a configuration option that is the complete
> > opposite of this and assumes are really embedded system.
> > Mark pages as always accessed, data pages as always dirty,
> > and you can eliminate lots of TLB faults in systems that are
> > fairly static.
> 
> It sounds tempting indeed, but should you really notice a performance increase 
> out of this?

Compared to 8xx in 2.6 today?  Absolutely.

-- 
Tom Rini
http://gate.crashing.org/~trini/