Re: page_launder() on 2.4.9/10 issue

[Jan Harkes]

On Tue, Sep 04, 2001 at 01:27:50PM -0300, Rik van Riel wrote:
> I've been working on a CPU and memory efficient reverse
> mapping patch for Linux, one which will allow us to do
> a bunch of optimisations for later on (infrastructure)
> and has as its short-term benefit the potential for
> better page aging.

Yes, I can see that using reverse mappings would be a way of correcting
the aging if you call page_age_up from try_to_swap_out, in which case
there probably needs to be a page_age_down on virtual mappings as well
to correctly balance things.

> It seems the balancing FreeBSD does (up aging +3, down
> aging -1, inactive list in LRU order as extra stage) is

One other observation, we should add anonymously allocated memory to the
active-list as soon as they are allocated in do_nopage. At the moment a
large part of memory is not aged at all until we start swapping things
out.

Jan