How to track the LRU pages access?

How to track the LRU pages access?

[Jin Huang]

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Hi, everyone
My name is Jin Huang, a graduate student interested in Linux Kernel.
Hope I ask the question in the right place.

I want to track the access activity of the pages in the LUR lists,
including Anon/File active/inactive lists, the access times and stuff.

(1) I find a function very interesting and promising, void
folio_mark_accessed(struct folio *folio), in mm/swap.c in linux v6.0.
Looking at the comment, seems it is used to mark the page access for the
LRU algorithm.
(2) I try to use some conditions,
like folio_test_lru, folio_test_anon, folio_test_active, to collect the
access information for anon_[in/]activelist, file_[in/]activelist.
(3) From this experiment, I found I could not get the information I want.

Seems there are always, even I do not run any application, many many file
pages access(for system) coming into folio_mark_accessed();
Even though I run some large memory-intensive application workload, the
information of the anon pages I get from this function is so limited, only
about 200 page access for a more than 50G memory consumption workload.

I want to ask/confirm folio_mark_accessed() does not track every page
access as I expect, right?
Do you have some suggestions if I want to track the LRU page access
information? Especially for the application pages.


Thank You
Best
Jin Huang

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