[PATCH v5 09/10] mm: multigenerational lru: Kconfig

[Yu Zhao]

Add configuration options for the multigenerational lru.

Signed-off-by: Yu Zhao <yuzhao at google.com>
Tested-by: Konstantin Kharlamov <Hi-Angel at yandex.ru>
---
 mm/Kconfig | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/mm/Kconfig b/mm/Kconfig
index d16ba9249bc5..48e7babb22e5 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -896,4 +896,63 @@ config SECRETMEM
 
 source "mm/damon/Kconfig"
 
+# the multigenerational lru {
+config LRU_GEN
+	bool "Multigenerational LRU"
+	depends on MMU
+	# the following options may leave not enough spare bits in page->flags
+	depends on !MAXSMP && (64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP)
+	help
+	  A high performance LRU implementation to heavily overcommit workloads
+	  that are not IO bound. See Documentation/vm/multigen_lru.rst for
+	  details.
+
+	  Warning: do not enable this option unless you plan to use it because
+	  it introduces a small per-process and per-memcg and per-node memory
+	  overhead.
+
+config LRU_GEN_ENABLED
+	bool "Turn on by default"
+	depends on LRU_GEN
+	help
+	  The default value of /sys/kernel/mm/lru_gen/enabled is 0. This option
+	  changes it to 1.
+
+	  Warning: the default value is the fast path. See
+	  Documentation/static-keys.txt for details.
+
+config LRU_GEN_STATS
+	bool "Full stats for debugging"
+	depends on LRU_GEN
+	help
+	  This option keeps full stats for each generation, which can be read
+	  from /sys/kernel/debug/lru_gen_full.
+
+	  Warning: do not enable this option unless you plan to use it because
+	  it introduces an additional small per-process and per-memcg and
+	  per-node memory overhead.
+
+config NR_LRU_GENS
+	int "Max number of generations"
+	depends on LRU_GEN
+	range 4 31
+	default 7
+	help
+	  This will use order_base_2(N+1) spare bits from page flags.
+
+	  Warning: do not use numbers larger than necessary because each
+	  generation introduces a small per-node and per-memcg memory overhead.
+
+config TIERS_PER_GEN
+	int "Number of tiers per generation"
+	depends on LRU_GEN
+	range 2 5
+	default 4
+	help
+	  This will use N-2 spare bits from page flags.
+
+	  Larger values generally offer better protection to active pages under
+	  heavy buffered I/O workloads.
+# }
+
 endmenu
-- 
2.34.0.rc0.344.g81b53c2807-goog