From: Barry Song <v-songbaohua@xxxxxxxx>
The doc needs update. As only in the case of virtual address, we are
calling madvise() with MADV_PAGEOUT; but in the case of physical
address, we are actually calling reclaim_pages() directly. And
madvise() with MADV_PAGEOUT is much more aggresive on reclamation
compared to reclaim_pages() on paddr.
Cc: SeongJae Park <sj@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
---
Documentation/mm/damon/design.rst | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index 8c89d26f0baa..6c50743552f5 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -315,7 +315,13 @@ that supports each action are as below.
Supported by ``vaddr`` and ``fvaddr`` operations set.
- ``cold``: Call ``madvise()`` for the region with ``MADV_COLD``.
Supported by ``vaddr`` and ``fvaddr`` operations set.
- - ``pageout``: Call ``madvise()`` for the region with ``MADV_PAGEOUT``.
+ - ``pageout``: Call ``madvise()`` for the region with ``MADV_PAGEOUT`` if
+ the region is using virtual address; otherwise, call ``reclaim_pages()``
+ for the region if physical address is used.
+ ``madvise()`` with ``MADV_PAGEOUT`` is aggressively reclaiming memory
+ when pages are not shared by multiple processes. Differently, paddr's
+ pageout will do the best-effort reclamation by scanning PTEs to figure
+ out if pages are young, if not, pages are reclaimed.
Supported by ``vaddr``, ``fvaddr`` and ``paddr`` operations set.
- ``hugepage``: Call ``madvise()`` for the region with ``MADV_HUGEPAGE``.
Supported by ``vaddr`` and ``fvaddr`` operations set.
--
2.34.1
