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authorT.J. Alumbaugh <talumbau@google.com>2023-01-18 03:18:21 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-02-03 09:33:26 +0300
commit7b8144e63d84716f16a1b929e0c7e03ae5c4d5c1 (patch)
tree2fae6ecc7f9c29d6654fbffe929d53147c355010 /Documentation/mm
parentb2db9ef2c0926ba86898136704cdc757c7a5a60a (diff)
downloadlinux-7b8144e63d84716f16a1b929e0c7e03ae5c4d5c1.tar.xz
mm: multi-gen LRU: section for working set protection
Patch series "mm: multi-gen LRU: improve". This patch series improves a few MGLRU functions, collects related functions, and adds additional documentation. This patch (of 7): Add a section for working set protection in the code and the design doc. The admin doc already contains its usage. Link: https://lkml.kernel.org/r/20230118001827.1040870-1-talumbau@google.com Link: https://lkml.kernel.org/r/20230118001827.1040870-2-talumbau@google.com Signed-off-by: T.J. Alumbaugh <talumbau@google.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'Documentation/mm')
-rw-r--r--Documentation/mm/multigen_lru.rst15
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/mm/multigen_lru.rst b/Documentation/mm/multigen_lru.rst
index d8f721f98868..6e1483e70fdc 100644
--- a/Documentation/mm/multigen_lru.rst
+++ b/Documentation/mm/multigen_lru.rst
@@ -141,6 +141,21 @@ loop has detected outlying refaults from the tier this page is in. To
this end, the feedback loop uses the first tier as the baseline, for
the reason stated earlier.
+Working set protection
+----------------------
+Each generation is timestamped at birth. If ``lru_gen_min_ttl`` is
+set, an ``lruvec`` is protected from the eviction when its oldest
+generation was born within ``lru_gen_min_ttl`` milliseconds. In other
+words, it prevents the working set of ``lru_gen_min_ttl`` milliseconds
+from getting evicted. The OOM killer is triggered if this working set
+cannot be kept in memory.
+
+This time-based approach has the following advantages:
+
+1. It is easier to configure because it is agnostic to applications
+ and memory sizes.
+2. It is more reliable because it is directly wired to the OOM killer.
+
Summary
-------
The multi-gen LRU can be disassembled into the following parts: