Add configuration options for the multigenerational lru.
Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx>
Tested-by: Konstantin Kharlamov <Hi-Angel@xxxxxxxxx>
---
Documentation/vm/multigen_lru.rst | 18 ++++++++++++
mm/Kconfig | 48 +++++++++++++++++++++++++++++++
2 files changed, 66 insertions(+)
diff --git a/Documentation/vm/multigen_lru.rst b/Documentation/vm/multigen_lru.rst
index 6f9e0181348b..a54c5637c455 100644
--- a/Documentation/vm/multigen_lru.rst
+++ b/Documentation/vm/multigen_lru.rst
@@ -6,6 +6,13 @@ Multigenerational LRU
Quick start
===========
+Build configurations
+--------------------
+:Required: Set ``CONFIG_LRU_GEN=y``.
+
+:Optional: Set ``CONFIG_LRU_GEN_ENABLED=y`` to enable this feature by
+ default.
+
Runtime configurations
----------------------
:Required: Write ``1`` to ``/sys/kernel/mm/lru_gen/enable`` if the
@@ -25,6 +32,17 @@ Personal computers
Data centers
------------
+:Optional: Change ``CONFIG_NR_LRU_GENS`` to a larger value to support
+ more generations for ``Working set estimation`` and
+ ``Proactive reclaim``.
+
+:Optional: Change ``CONFIG_TIERS_PER_GEN`` to a larger value to
+ support more tiers, which generally provide better protection for
+ page cache when under heavy buffered I/O workloads.
+
+:Optional: Set ``CONFIG_LRU_GEN_STATS=y`` to enable full stats for
+ debugging. See ``Debugfs interface``.
+
:Debugfs interface: ``/sys/kernel/debug/lru_gen`` has the following
format:
::
diff --git a/mm/Kconfig b/mm/Kconfig
index 356f4f2c779e..8a33605917f5 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -900,6 +900,54 @@ config IO_MAPPING
config SECRETMEM
def_bool ARCH_HAS_SET_DIRECT_MAP && !EMBEDDED
+# multigenerational lru {
+config LRU_GEN
+ bool "Multigenerational LRU"
+ depends on MMU
+ # the following options can use up the spare bits in page flags
+ depends on !MAXSMP && (64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP)
+ help
+ A high performance LRU implementation for memory overcommit. See
+ Documentation/vm/multigen_lru.rst for details.
+
+config LRU_GEN_ENABLED
+ bool "Enable by default"
+ depends on LRU_GEN
+ help
+ This option enables the multigenerational lru by default.
+
+config NR_LRU_GENS
+ int "Max number of generations"
+ depends on LRU_GEN
+ range 4 31
+ default 4
+ help
+ This option uses order_base_2(N+1) bits in page flags.
+
+ Do not configure more generations than you plan to use. They have a
+ per-memcg and per-node memory overhead.
+
+config TIERS_PER_GEN
+ int "Number of tiers per generation"
+ depends on LRU_GEN
+ range 2 5
+ default 4
+ help
+ This option uses N-2 bits in page flags.
+
+ Larger values generally provide better protection for page cache when
+ under heavy buffered I/O workloads.
+
+config LRU_GEN_STATS
+ bool "Full stats for debugging"
+ depends on LRU_GEN
+ help
+ This option keeps historical stats for evicted generations.
+
+ Do not enable full stats unless you plan to look at them. They have a
+ per-memcg and per-node memory overhead.
+# }
+
source "mm/damon/Kconfig"
endmenu
--
2.34.1.448.ga2b2bfdf31-goog
