memory priorities

[Benjamin LaHaise <bcrl@kvack.org>]

Grr... I should 'fix' this ;-)
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From: Rik van Riel <H.H.vanRiel@fys.ruu.nl>
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To: Pavel Machek <pavel@Elf.mj.gts.cz>
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Subject: memory priorities
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On Wed, 17 Dec 1997, Pavel Machek wrote:

[snip Pavel (?) implemented memory priorities]
> > > But proved to be pretty ineffective. I came to this idea when I
> > > realized that to cook machine, running 100 processes will not hurt too
> > > much. But running 10 processes, 50 megabytes each will cook almost
> > > anything...
> > 
> > what about:
> > 
> > if (page->age - p->mem_priority)
> > 	exit 0 / goto next;
> > else {
> > 	get_rid_of(page);
> > 	and_dont_show_your_face_again_for_some_time(page);
> > }
> 
> I tried only manipulating comparasion, and not putting in into
> sleep. I did not find benchmark where it does any performance
> gain. ;-) Seems like it does nearly nothing.

Well, if you only swap out the page, it will be swapped
in quite soon and the only effect is that your system
will have more pagefaults...

If there is some free field in the page-table (once the
page gets swapped out) we could use it to indicate that
the system should wait some time with swapping this one
in again...

Rik.
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