68 lines
2.5 KiB
Diff
68 lines
2.5 KiB
Diff
From 1b5e4c317d80f4826eceb3781702d18d06b14394 Mon Sep 17 00:00:00 2001
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From: "T.J. Alumbaugh" <talumbau@google.com>
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Date: Wed, 18 Jan 2023 00:18:21 +0000
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Subject: [PATCH 12/19] UPSTREAM: mm: multi-gen LRU: section for working set
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protection
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Patch series "mm: multi-gen LRU: improve".
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This patch series improves a few MGLRU functions, collects related
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functions, and adds additional documentation.
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This patch (of 7):
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Add a section for working set protection in the code and the design doc.
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The admin doc already contains its usage.
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Link: https://lkml.kernel.org/r/20230118001827.1040870-1-talumbau@google.com
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Link: https://lkml.kernel.org/r/20230118001827.1040870-2-talumbau@google.com
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Change-Id: I65599075fd42951db7739a2ab7cee78516e157b3
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Signed-off-by: T.J. Alumbaugh <talumbau@google.com>
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Cc: Yu Zhao <yuzhao@google.com>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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(cherry picked from commit 7b8144e63d84716f16a1b929e0c7e03ae5c4d5c1)
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Bug: 274865848
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Signed-off-by: T.J. Mercier <tjmercier@google.com>
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---
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Documentation/mm/multigen_lru.rst | 15 +++++++++++++++
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mm/vmscan.c | 4 ++++
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2 files changed, 19 insertions(+)
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--- a/Documentation/mm/multigen_lru.rst
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+++ b/Documentation/mm/multigen_lru.rst
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@@ -141,6 +141,21 @@ loop has detected outlying refaults from
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this end, the feedback loop uses the first tier as the baseline, for
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the reason stated earlier.
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+Working set protection
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+----------------------
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+Each generation is timestamped at birth. If ``lru_gen_min_ttl`` is
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+set, an ``lruvec`` is protected from the eviction when its oldest
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+generation was born within ``lru_gen_min_ttl`` milliseconds. In other
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+words, it prevents the working set of ``lru_gen_min_ttl`` milliseconds
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+from getting evicted. The OOM killer is triggered if this working set
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+cannot be kept in memory.
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+
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+This time-based approach has the following advantages:
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+
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+1. It is easier to configure because it is agnostic to applications
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+ and memory sizes.
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+2. It is more reliable because it is directly wired to the OOM killer.
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+
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Summary
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-------
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The multi-gen LRU can be disassembled into the following parts:
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--- a/mm/vmscan.c
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+++ b/mm/vmscan.c
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@@ -4461,6 +4461,10 @@ done:
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return true;
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}
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+/******************************************************************************
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+ * working set protection
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+ ******************************************************************************/
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+
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static bool lruvec_is_sizable(struct lruvec *lruvec, struct scan_control *sc)
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{
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int gen, type, zone;
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