Re: rw_swap_page() and swapin readahead

[Rik van Riel <H.H.vanRiel@phys.uu.nl>]

On Wed, 25 Nov 1998, Stephen C. Tweedie wrote:
> On Wed, 25 Nov 1998 23:02:30 +0100 (CET), Rik van Riel
> <H.H.vanRiel@phys.uu.nl> said:
> 
> > it appears that rw_swap_page() needs a small change to be
> > able to do asynchonous swapin.
> 
> > On line 128:
> > 		if (!wait) {
> > 			set_bit(PG_free_after, &page->flags);
			set_bit(PG_decr_after, &page->flags);
			set_bit(PG_swap_unlock_after, &page->flags);
			atomic_inc(&nr_async_pages);
> > 		}
> 
> The PG_free_after bit is there only to mark that increment, so that
> the page count is decremented again (asynchronously) once the IO is
> complete and no sooner. 

Then what does the PG_decr_after do? It seems like there
are two flags to do the same thing... I'm curious :)

cheers,

Rik -- slowly getting used to dvorak kbd layout...
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| Linux memory management tour guide.        H.H.vanRiel@phys.uu.nl |
| Scouting Vries cubscout leader.      http://www.phys.uu.nl/~riel/ |
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