From 8c987beaae2bdfa3fb35468fe681a9b57f064fc8 Mon Sep 17 00:00:00 2001 From: Yu Zhao Date: Mon, 25 Jan 2021 21:47:24 -0700 Subject: [PATCH] BACKPORT: FROMLIST: mm: multigenerational lru: Kconfig Add configuration options for the multigenerational lru. Signed-off-by: Yu Zhao Tested-by: Konstantin Kharlamov (am from https://lore.kernel.org/patchwork/patch/1432188/) BUG=b:123039911 TEST=Built Change-Id: Ic74ea07f8fb5f56e6904a1b80c3c286bc2911635 Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2987192 Reviewed-by: Yu Zhao Tested-by: Yu Zhao Commit-Queue: Sonny Rao Commit-Queue: Yu Zhao --- mm/Kconfig | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) --- a/mm/Kconfig +++ b/mm/Kconfig @@ -723,4 +723,63 @@ config ARCH_HAS_PTE_SPECIAL config ARCH_HAS_HUGEPD bool +# the multigenerational lru { +config LRU_GEN + bool "Multigenerational LRU" + depends on MMU + # the following options may consume too many 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