From 3008095eb835d207dd7e5b60899aad17f32aa9f7 Mon Sep 17 00:00:00 2001 From: Yu Zhao Date: Mon, 25 Jan 2021 21:47:24 -0700 Subject: [PATCH 09/10] mm: multigenerational lru: Kconfig Add configuration options for the multigenerational lru. Signed-off-by: Yu Zhao Tested-by: Konstantin Kharlamov Change-Id: Ic74ea07f8fb5f56e6904a1b80c3c286bc2911635 --- mm/Kconfig | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) --- a/mm/Kconfig +++ b/mm/Kconfig @@ -899,4 +899,63 @@ 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