Re: Plain 2.4.5 VM

[Mark Hahn <hahn@coffee.psychology.mcmaster.ca>]

> The "easy way out" seems to be physical -> virtual
> page reverse mappings, these make it trivial to apply
> balanced pressure on all pages.

hmm, I've been wondering if one of our problems is that while
the active/inactive-clean/inactive-dirty system does well
at preserving age info, but the only place we actually
*learn* NEW information about page use is in try_to_swap_out:

	if (ptep_test_and_clear_young(pte))
		age up;
	else		
		get rid of it;

shouldn't we try to gain more information by scanning page tables
at a good rate?  we don't have to blindly get rid of every page
that isn't young (referenced since last scan) - we could base that
on age.  admittedly, more scanning would eat some additional CPU,
but then again, we currently shuffle pages among lists based on relatively
sparse PAGE_ACCESSED info.

or am I missing something?  

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