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Mina Almasry 12a5d39552 mm: add nodes= arg to memory.reclaim
The nodes= arg instructs the kernel to only scan the given nodes for
proactive reclaim.  For example use cases, consider a 2 tier memory
system:

nodes 0,1 -> top tier
nodes 2,3 -> second tier

$ echo "1m nodes=0" > memory.reclaim

This instructs the kernel to attempt to reclaim 1m memory from node 0. 
Since node 0 is a top tier node, demotion will be attempted first.  This
is useful to direct proactive reclaim to specific nodes that are under
pressure.

$ echo "1m nodes=2,3" > memory.reclaim

This instructs the kernel to attempt to reclaim 1m memory in the second
tier, since this tier of memory has no demotion targets the memory will be
reclaimed.

$ echo "1m nodes=0,1" > memory.reclaim

Instructs the kernel to reclaim memory from the top tier nodes, which can
be desirable according to the userspace policy if there is pressure on the
top tiers.  Since these nodes have demotion targets, the kernel will
attempt demotion first.

Since commit 3f1509c57b ("Revert "mm/vmscan: never demote for memcg
reclaim""), the proactive reclaim interface memory.reclaim does both
reclaim and demotion.  Reclaim and demotion incur different latency costs
to the jobs in the cgroup.  Demoted memory would still be addressable by
the userspace at a higher latency, but reclaimed memory would need to
incur a pagefault.

The 'nodes' arg is useful to allow the userspace to control demotion and
reclaim independently according to its policy: if the memory.reclaim is
called on a node with demotion targets, it will attempt demotion first; if
it is called on a node without demotion targets, it will only attempt
reclaim.

Link: https://lkml.kernel.org/r/20221202223533.1785418-1-almasrymina@google.com
Signed-off-by: Mina Almasry <almasrymina@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Muchun Song <songmuchun@bytedance.com>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Tejun Heo <tj@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: zefan li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-12-11 18:12:19 -08:00
arch LoongArch: enable ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP 2022-12-11 18:12:12 -08:00
block block-6.1-2022-11-05 2022-11-05 09:02:28 -07:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto treewide: use get_random_bytes() when possible 2022-10-11 17:42:58 -06:00
Documentation mm: add nodes= arg to memory.reclaim 2022-12-11 18:12:19 -08:00
drivers zram: remove unused stats fields 2022-11-30 15:59:01 -08:00
fs omfs: remove ->writepage 2022-12-11 18:12:18 -08:00
include mm: add nodes= arg to memory.reclaim 2022-12-11 18:12:19 -08:00
init init: Kconfig: fix spelling mistake "satify" -> "satisfy" 2022-10-20 21:27:22 -07:00
io_uring io_uring: unlock if __io_run_local_work locked inside 2022-10-27 09:52:12 -06:00
ipc ipc/shm: call underlying open/close vm_ops 2022-11-22 18:50:42 -08:00
kernel lockdep: allow instrumenting lockdep.c with KMSAN 2022-12-11 18:12:11 -08:00
lib maple_tree: allow TEST_MAPLE_TREE only when DEBUG_KERNEL is set 2022-11-30 15:59:03 -08:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: add nodes= arg to memory.reclaim 2022-12-11 18:12:19 -08:00
net Networking fixes for 6.1-rc4, including fixes from bluetooth and 2022-11-03 10:51:59 -07:00
rust Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
samples VFIO updates for v6.1-rc1 2022-10-12 14:46:48 -07:00
scripts kconfig: fix segmentation fault in menuconfig search 2022-11-02 17:32:05 +09:00
security lsm/stable-6.1 PR 20221031 2022-10-31 12:09:42 -07:00
sound ALSA: aoa: Fix I2S device accounting 2022-10-27 08:53:08 +02:00
tools selftests: cgroup: make sure reclaim target memcg is unprotected 2022-12-11 18:12:19 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt Merge tag 'kvmarm-fixes-6.1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD 2022-11-06 03:30:49 -05:00
.clang-format PCI/DOE: Add DOE mailbox support functions 2022-07-19 15:38:04 -07:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap MAINTAINERS: update Muchun Song's email 2022-12-09 18:41:17 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS drm for 5.20/6.0 2022-08-03 19:52:08 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge branch 'mm-hotfixes-stable' into mm-stable 2022-12-09 19:31:11 -08:00
Makefile Linux 6.1-rc4 2022-11-06 15:07:11 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.