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Baolin Wang d2136d749d mm: support multi-size THP numa balancing Now the anonymous page allocation already supports multi-size THP (mTHP), but the numa balancing still prohibits mTHP migration even though it is an exclusive mapping, which is unreasonable. Allow scanning mTHP: Commit `859d4adc34` ("mm: numa: do not trap faults on shared data section pages") skips shared CoW pages' NUMA page migration to avoid shared data segment migration. In addition, commit `80d47f5de5` ("mm: don't try to NUMA-migrate COW pages that have other uses") change to use page_count() to avoid GUP pages migration, that will also skip the mTHP numa scanning. Theoretically, we can use folio_maybe_dma_pinned() to detect the GUP issue, although there is still a GUP race, the issue seems to have been resolved by commit `80d47f5de5`. Meanwhile, use the folio_likely_mapped_shared() to skip shared CoW pages though this is not a precise sharers count. To check if the folio is shared, ideally we want to make sure every page is mapped to the same process, but doing that seems expensive and using the estimated mapcount seems can work when running autonuma benchmark. Allow migrating mTHP: As mentioned in the previous thread[1], large folios (including THP) are more susceptible to false sharing issues among threads than 4K base page, leading to pages ping-pong back and forth during numa balancing, which is currently not easy to resolve. Therefore, as a start to support mTHP numa balancing, we can follow the PMD mapped THP's strategy, that means we can reuse the 2-stage filter in should_numa_migrate_memory() to check if the mTHP is being heavily contended among threads (through checking the CPU id and pid of the last access) to avoid false sharing at some degree. Thus, we can restore all PTE maps upon the first hint page fault of a large folio to follow the PMD mapped THP's strategy. In the future, we can continue to optimize the NUMA balancing algorithm to avoid the false sharing issue with large folios as much as possible. Performance data: Machine environment: 2 nodes, 128 cores Intel(R) Xeon(R) Platinum Base: 2024-03-25 mm-unstable branch Enable mTHP to run autonuma-benchmark mTHP:16K Base Patched numa01 numa01 224.70 143.48 numa01_THREAD_ALLOC numa01_THREAD_ALLOC 118.05 47.43 numa02 numa02 13.45 9.29 numa02_SMT numa02_SMT 14.80 7.50 mTHP:64K Base Patched numa01 numa01 216.15 114.40 numa01_THREAD_ALLOC numa01_THREAD_ALLOC 115.35 47.41 numa02 numa02 13.24 9.25 numa02_SMT numa02_SMT 14.67 7.34 mTHP:128K Base Patched numa01 numa01 205.13 144.45 numa01_THREAD_ALLOC numa01_THREAD_ALLOC 112.93 41.88 numa02 numa02 13.16 9.18 numa02_SMT numa02_SMT 14.81 7.49 [1] https://lore.kernel.org/all/20231117100745.fnpijbk4xgmals3k@techsingularity.net/ [baolin.wang@linux.alibaba.com: v3] Link: https://lkml.kernel.org/r/c33a5c0b0a0323b1f8ed53772f50501f4b196e25.1712132950.git.baolin.wang@linux.alibaba.com Link: https://lkml.kernel.org/r/d28d276d599c26df7f38c9de8446f60e22dd1950.1711683069.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Ryan Roberts <ryan.roberts@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>		2024-04-25 20:56:30 -07:00
arch	x86/mm: care about shadow stack guard gap during placement	2024-04-25 20:56:28 -07:00
block	block-6.9-20240412	2024-04-12 10:22:33 -07:00
certs	This update includes the following changes:	2023-11-02 16:15:30 -10:00
crypto	This push fixes a regression that broke iwd as well as a divide by	2024-03-25 10:48:23 -07:00
Documentation	zram: add max_pages param to recompression	2024-04-25 20:56:30 -07:00
drivers	zram: add max_pages param to recompression	2024-04-25 20:56:30 -07:00
fs	mm/ksm: fix ksm exec support for prctl	2024-04-25 20:56:29 -07:00
include	mm: init_mlocked_on_free_v3	2024-04-25 20:56:29 -07:00
init	mm: introduce slabobj_ext to support slab object extensions	2024-04-25 20:55:51 -07:00
io_uring	mm: switch mm->get_unmapped_area() to a flag	2024-04-25 20:56:25 -07:00
ipc	sysctl changes for v6.9-rc1	2024-03-18 14:59:13 -07:00
kernel	mm: switch mm->get_unmapped_area() to a flag	2024-04-25 20:56:25 -07:00
lib	mm/filemap: optimize filemap folio adding	2024-04-25 20:56:09 -07:00
LICENSES	LICENSES: Add the copyleft-next-0.3.1 license	2022-11-08 15:44:01 +01:00
mm	mm: support multi-size THP numa balancing	2024-04-25 20:56:30 -07:00
net	mm: change inlined allocation helpers to account at the call site	2024-04-25 20:55:59 -07:00
rust	rust: add a rust helper for krealloc()	2024-04-25 20:55:55 -07:00
samples	Tracing updates for 6.9:	2024-03-18 15:11:44 -07:00
scripts	lib: add allocation tagging support for memory allocation profiling	2024-04-25 20:55:52 -07:00
security	mm: init_mlocked_on_free_v3	2024-04-25 20:56:29 -07:00
sound	fix missing vmalloc.h includes	2024-04-25 20:55:49 -07:00
tools	selftest/mm: ksm_functional_tests: extend test case for ksm fork/exec	2024-04-25 20:56:29 -07:00
usr	Kbuild updates for v6.8	2024-01-18 17:57:07 -08:00
virt	KVM Xen and pfncache changes for 6.9:	2024-03-11 10:42:55 -04:00
.clang-format	clang-format: Update with v6.7-rc4's `for_each` macro list	2023-12-08 23:54:38 +01:00
.cocciconfig
.editorconfig	Add .editorconfig file for basic formatting	2023-12-28 16:22:47 +09:00
.get_maintainer.ignore	Add Jeff Kirsher to .get_maintainer.ignore	2024-03-08 11:36:54 +00:00
.gitattributes	.gitattributes: set diff driver for Rust source code files	2023-05-31 17:48:25 +02:00
.gitignore	kbuild: create a list of all built DTB files	2024-02-19 18:20:39 +09:00
.mailmap	MAINTAINERS: update Naoya Horiguchi's email address	2024-04-16 15:39:51 -07:00
.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	MAINTAINERS: Drop Gustavo Pimentel as PCI DWC Maintainer	2024-03-27 13:41:02 -05:00
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	MAINTAINERS: add entries for code tagging and memory allocation profiling	2024-04-25 20:55:58 -07:00
Makefile	Linux 6.9-rc4	2024-04-14 13:38:39 -07:00
README	README: Fix spelling	2024-03-18 03:36:32 -06:00

README

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 reStructuredText 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.