Hi, I am a novice working with 2.4.20. I have a couple of questions w.r.t
shrink_caches and try_to_swap_out - help is greatly appreciated.
try_to_swap_out is adding pages to the swap_cache but I don't see the code
where it is actually swapping out... is the swap out meant to be done in
the next pass in the shrink_cache function where if a page has mapping,
writepage is called ? So, anonymous pages which do not have any buffers
are swapped this way ? At the same time, if this is a page that has
buffers, then it is done through try_to_release_page ->
try_to_free_buffers ->.. - correct ?
was wondering how the movement between the inactive and active lists is
triggered ? in the kswapd code, refill_inactive moves the non-referenced
pages to the inactive list and try_to_swap_out checks the PTE and if the
page has recently been accessed, sets the reference bit and moves it into
the active list if it not there. now, when a new page is being
created[do_page_fault],
do_page_fault
1 do_no_page
a -> do_anonymous_page -> lru_cache_add + mark_page_accessed
[essentially adding to the active list]
b -> vm_ops defined => lru_cache_add
[adding to inactive list]
2 do_swap_page
-> lru_cache_add + mark_page_accessed
[adding to active list]
3 do_wp_page
-> lru_cache_add [adding to inactive list]
Why is this difference ? - why are 1a and 2 to the active list and 1b and
3 to the inactive list ?
Also, when is an anonymous page[belonging to a heap or stack of a process]
moved into the swap xactly ? - are buffers ever created for this page ?
is it possiblt for a page to be in the active list and swap cache ?
Thanks alot!
-gokul--
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