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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
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
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.