diff options
Diffstat (limited to 'target/linux/generic/backport-5.15/020-v6.1-10-mm-multigenerational-lru-documentation.patch')
| -rw-r--r-- | target/linux/generic/backport-5.15/020-v6.1-10-mm-multigenerational-lru-documentation.patch | 161 |
1 files changed, 0 insertions, 161 deletions
diff --git a/target/linux/generic/backport-5.15/020-v6.1-10-mm-multigenerational-lru-documentation.patch b/target/linux/generic/backport-5.15/020-v6.1-10-mm-multigenerational-lru-documentation.patch deleted file mode 100644 index f4716fb68d..0000000000 --- a/target/linux/generic/backport-5.15/020-v6.1-10-mm-multigenerational-lru-documentation.patch +++ /dev/null @@ -1,161 +0,0 @@ -From f59c618ed70a1e48accc4cad91a200966f2569c9 Mon Sep 17 00:00:00 2001 -From: Yu Zhao <yuzhao@google.com> -Date: Tue, 2 Feb 2021 01:27:45 -0700 -Subject: [PATCH 10/10] mm: multigenerational lru: documentation - -Add Documentation/vm/multigen_lru.rst. - -Signed-off-by: Yu Zhao <yuzhao@google.com> -Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru> -Change-Id: I1902178bcbb5adfa0a748c4d284a6456059bdd7e ---- - Documentation/vm/index.rst | 1 + - Documentation/vm/multigen_lru.rst | 132 ++++++++++++++++++++++++++++++ - 2 files changed, 133 insertions(+) - create mode 100644 Documentation/vm/multigen_lru.rst - ---- a/Documentation/vm/index.rst -+++ b/Documentation/vm/index.rst -@@ -17,6 +17,7 @@ various features of the Linux memory man - - swap_numa - zswap -+ multigen_lru - - Kernel developers MM documentation - ================================== ---- /dev/null -+++ b/Documentation/vm/multigen_lru.rst -@@ -0,0 +1,132 @@ -+.. SPDX-License-Identifier: GPL-2.0 -+ -+===================== -+Multigenerational LRU -+===================== -+ -+Quick Start -+=========== -+Build Configurations -+-------------------- -+:Required: Set ``CONFIG_LRU_GEN=y``. -+ -+:Optional: Set ``CONFIG_LRU_GEN_ENABLED=y`` to turn the feature on by -+ default. -+ -+Runtime Configurations -+---------------------- -+:Required: Write ``1`` to ``/sys/kernel/mm/lru_gen/enable`` if the -+ feature was not turned on by default. -+ -+:Optional: Write ``N`` to ``/sys/kernel/mm/lru_gen/min_ttl_ms`` to -+ protect the working set of ``N`` milliseconds. The OOM killer is -+ invoked if this working set cannot be kept in memory. -+ -+:Optional: Read ``/sys/kernel/debug/lru_gen`` to confirm the feature -+ is turned on. This file has the following output: -+ -+:: -+ -+ memcg memcg_id memcg_path -+ node node_id -+ min_gen birth_time anon_size file_size -+ ... -+ max_gen birth_time anon_size file_size -+ -+``min_gen`` is the oldest generation number and ``max_gen`` is the -+youngest generation number. ``birth_time`` is in milliseconds. -+``anon_size`` and ``file_size`` are in pages. -+ -+Phones/Laptops/Workstations -+--------------------------- -+No additional configurations required. -+ -+Servers/Data Centers -+-------------------- -+:To support more generations: Change ``CONFIG_NR_LRU_GENS`` to a -+ larger number. -+ -+:To support more tiers: Change ``CONFIG_TIERS_PER_GEN`` to a larger -+ number. -+ -+:To support full stats: Set ``CONFIG_LRU_GEN_STATS=y``. -+ -+:Working set estimation: Write ``+ memcg_id node_id max_gen -+ [swappiness] [use_bloom_filter]`` to ``/sys/kernel/debug/lru_gen`` to -+ invoke the aging, which scans PTEs for accessed pages and then -+ creates the next generation ``max_gen+1``. A swap file and a non-zero -+ ``swappiness``, which overrides ``vm.swappiness``, are required to -+ scan PTEs mapping anon pages. Set ``use_bloom_filter`` to 0 to -+ override the default behavior which only scans PTE tables found -+ populated. -+ -+:Proactive reclaim: Write ``- memcg_id node_id min_gen [swappiness] -+ [nr_to_reclaim]`` to ``/sys/kernel/debug/lru_gen`` to invoke the -+ eviction, which evicts generations less than or equal to ``min_gen``. -+ ``min_gen`` should be less than ``max_gen-1`` as ``max_gen`` and -+ ``max_gen-1`` are not fully aged and therefore cannot be evicted. -+ Use ``nr_to_reclaim`` to limit the number of pages to evict. Multiple -+ command lines are supported, so does concatenation with delimiters -+ ``,`` and ``;``. -+ -+Framework -+========= -+For each ``lruvec``, evictable pages are divided into multiple -+generations. The youngest generation number is stored in -+``lrugen->max_seq`` for both anon and file types as they are aged on -+an equal footing. The oldest generation numbers are stored in -+``lrugen->min_seq[]`` separately for anon and file types as clean -+file pages can be evicted regardless of swap and writeback -+constraints. These three variables are monotonically increasing. -+Generation numbers are truncated into -+``order_base_2(CONFIG_NR_LRU_GENS+1)`` bits in order to fit into -+``page->flags``. The sliding window technique is used to prevent -+truncated generation numbers from overlapping. Each truncated -+generation number is an index to an array of per-type and per-zone -+lists ``lrugen->lists``. -+ -+Each generation is divided into multiple tiers. Tiers represent -+different ranges of numbers of accesses from file descriptors only. -+Pages accessed ``N`` times via file descriptors belong to tier -+``order_base_2(N)``. Each generation contains at most -+``CONFIG_TIERS_PER_GEN`` tiers, and they require additional -+``CONFIG_TIERS_PER_GEN-2`` bits in ``page->flags``. In contrast to -+moving between generations which requires list operations, moving -+between tiers only involves operations on ``page->flags`` and -+therefore has a negligible cost. A feedback loop modeled after the PID -+controller monitors refaulted % across all tiers and decides when to -+protect pages from which tiers. -+ -+The framework comprises two conceptually independent components: the -+aging and the eviction, which can be invoked separately from user -+space for the purpose of working set estimation and proactive reclaim. -+ -+Aging -+----- -+The aging produces young generations. Given an ``lruvec``, the aging -+traverses ``lruvec_memcg()->mm_list`` and calls ``walk_page_range()`` -+to scan PTEs for accessed pages (a ``mm_struct`` list is maintained -+for each ``memcg``). Upon finding one, the aging updates its -+generation number to ``max_seq`` (modulo ``CONFIG_NR_LRU_GENS``). -+After each round of traversal, the aging increments ``max_seq``. The -+aging is due when ``min_seq[]`` reaches ``max_seq-1``. -+ -+Eviction -+-------- -+The eviction consumes old generations. Given an ``lruvec``, the -+eviction scans pages on the per-zone lists indexed by anon and file -+``min_seq[]`` (modulo ``CONFIG_NR_LRU_GENS``). It first tries to -+select a type based on the values of ``min_seq[]``. If they are -+equal, it selects the type that has a lower refaulted %. The eviction -+sorts a page according to its updated generation number if the aging -+has found this page accessed. It also moves a page to the next -+generation if this page is from an upper tier that has a higher -+refaulted % than the base tier. The eviction increments ``min_seq[]`` -+of a selected type when it finds all the per-zone lists indexed by -+``min_seq[]`` of this selected type are empty. -+ -+To-do List -+========== -+KVM Optimization -+---------------- -+Support shadow page table walk. |