Re: [PATCH] mm, vmscan: do not count freed pages as PGDEACTIVATE

From: Vlastimil Babka
Date: Fri Jan 13 2017 - 04:55:53 EST


On 01/12/2017 10:12 PM, Michal Hocko wrote:
From: Michal Hocko <mhocko@xxxxxxxx>

PGDEACTIVATE represents the number of pages moved from the active list
to the inactive list. At least this sounds like the original motivation
of the counter. move_active_pages_to_lru, however, counts pages which
got freed in the mean time as deactivated as well. This is a very rare
event and counting them as deactivation in itself is not harmful but it
makes the code more convoluted than necessary - we have to count both
all pages and those which are freed which is a bit confusing.

After this patch the PGDEACTIVATE should have a slightly more clear
semantic and only count those pages which are moved from the active to
the inactive list which is a plus.

Suggested-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>