f0001cff25c0795159531e2517ebc8868eb183faa2b30d95016c5314.patch

From a780e9ae2249ba8c5c9f6f91b5b98486cee12c15 Mon Sep 17 00:00:00 2001
From: Yu Zhao <yuzhao@google.com>
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 <yuzhao@google.com>
Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru>
(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/+/2987927
Tested-by: Yu Zhao <yuzhao@chromium.org>
Reviewed-by: Sonny Rao <sonnyrao@chromium.org>
Reviewed-by: Yu Zhao <yuzhao@chromium.org>
Commit-Queue: Yu Zhao <yuzhao@chromium.org>
---
 mm/Kconfig | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/mm/Kconfig b/mm/Kconfig
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -922,6 +922,63 @@ config LOW_MEM_NOTIFY
 	  the presence of large swap space, the system is likely to become
 	  unusable before the OOM killer is triggered.
 
+# the multigenerational lru {
+config LRU_GEN
+	bool "Multigenerational LRU"
+	depends on MMU && !MAXSMP
+	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.
+# }
+
 source "mm/damon/Kconfig"
 
 endmenu
-- 
2.33.0.464.g1972c5931b-goog