[PATCH v2 15/16] mm: multigenerational lru: Kconfig

Yu Zhao
2021-04-13T06:57:45Z

Add configuration options for the multigenerational lru.

Signed-off-by: Yu Zhao <yuzhao@google.com>
---
mm/Kconfig | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 55 insertions(+)

diff --git a/mm/Kconfig b/mm/Kconfig
index 24c045b24b95..0be1c6c90cc0 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -872,4 +872,59 @@ config MAPPING_DIRTY_HELPERS
config KMAP_LOCAL
bool

+config LRU_GEN
+ bool "Multigenerational LRU"
+ depends on MMU
+ 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 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.
+
+ Higher values generally offer better protection to active pages under
+ heavy buffered I/O workloads.
+
+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.
+
endmenu
--
2.31.1.295.g9ea45b61b8-goog