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2b3a58b121
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Kairui Song 2b3a58b121 mm/swap_cgroup: remove global swap cgroup lock 
commit e9e58a4ec3 ("memcg: avoid use cmpxchg in swap cgroup
maintainance") replaced the cmpxchg/xchg with a global irq spinlock
because some archs doesn't support 2 bytes cmpxchg/xchg.  Clearly this
won't scale well.

And as commented in swap_cgroup.c, this lock is not needed for map
synchronization.

Emulation of 2 bytes xchg with atomic cmpxchg isn't hard, so implement it
to get rid of this lock.  Introduced two helpers for doing so and they can
be easily dropped if a generic 2 byte xchg is support.

Testing using 64G brd and build with build kernel with make -j96 in 1.5G
memory cgroup using 4k folios showed below improvement (6 test run):

Before this series:
Sys time: 10782.29 (stdev 42.353886)
Real time: 171.49 (stdev 0.595541)

After this commit:
Sys time: 9617.23 (stdev 37.764062), -10.81%
Real time: 159.65 (stdev 0.587388), -6.90%

With 64k folios and 2G memcg:
Before this series:
Sys time: 8176.94 (stdev 26.414712)
Real time: 141.98 (stdev 0.797382)

After this commit:
Sys time: 7358.98 (stdev 54.927593), -10.00%
Real time: 134.07 (stdev 0.757463), -5.57%

Sequential swapout of 8G 64k zero folios with madvise (24 test run):
Before this series:
5461409.12 us (stdev 183957.827084)

After this commit:
5420447.26 us (stdev 196419.240317)

Sequential swapin of 8G 4k zero folios (24 test run):
Before this series:
19736958.916667 us (stdev 189027.246676)

After this commit:
19662182.629630 us (stdev 172717.640614)

Performance is better or at least not worse for all tests above.

Link: https://lkml.kernel.org/r/20241218114633.85196-4-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-01-25 20:22:19 -08:00
arch mm/early_ioremap: add null pointer checks to prevent NULL-pointer dereference 2025-01-13 22:40:59 -08:00
block block: avoid to reuse hctx not removed from cpuhp callback list 2024-12-18 07:25:37 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: rsassa-pkcs1 - Copy source data for SG list 2024-12-10 13:34:05 +08:00
Documentation mm: add per-order mTHP swap-in fallback/fallback_charge counters 2025-01-13 22:40:49 -08:00
drivers mm/early_ioremap: add null pointer checks to prevent NULL-pointer dereference 2025-01-13 22:40:59 -08:00
fs mm: perform all memfd seal checks in a single place 2025-01-13 22:40:51 -08:00
include mm/swap_cgroup: remove swap_cgroup_cmpxchg 2025-01-25 20:22:19 -08:00
init - The series "resource: A couple of cleanups" from Andy Shevchenko 2024-11-25 16:09:48 -08:00
io_uring io_uring/kbuf: use pre-committed buffer address for non-pollable file 2025-01-03 09:38:37 -07:00
ipc - The series "resource: A couple of cleanups" from Andy Shevchenko 2024-11-25 16:09:48 -08:00
kernel mm: convert mm_lock_seq to a proper seqcount 2025-01-13 22:40:50 -08:00
lib test_maple_tree: test exhausted upper limit of mtree_alloc_cyclic() 2025-01-25 20:22:19 -08:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm/swap_cgroup: remove global swap cgroup lock 2025-01-25 20:22:19 -08:00
net Nothing major here. Over the last two weeks we gathered only around 2025-01-03 14:36:54 -08:00
rust workqueue: Fixes for v6.13-rc5 2025-01-03 15:03:56 -08:00
samples samples/damon/prcl: implement schemes setup 2025-01-13 22:40:57 -08:00
scripts scripts/decode_stacktrace.sh: fix decoding of lines with an additional info 2025-01-12 19:03:34 -08:00
security selinux/stable-6.13 PR 20241217 2024-12-18 12:10:15 -08:00
sound sound fixes for 6.13-rc6 2025-01-03 10:54:51 -08:00
tools tools: testing: add simple __mmap_region() userland test 2025-01-25 20:22:18 -08:00
usr kbuild: Drop support for include/asm-<arch> in headers_check.pl 2024-12-21 11:43:17 +09:00
virt VFIO updates for v6.13 2024-11-27 12:57:03 -08:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: enable Clippy's check-private-items 2024-10-07 21:39:57 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Kbuild updates for v6.13 2024-11-30 13:41:50 -08:00
.mailmap mailmap: modify the entry for Mathieu Othacehe 2024-12-30 17:59:08 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS cgroup: Changes for v6.13 2024-11-20 09:54:49 -08:00
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: update MEMORY MAPPING section 2025-01-13 22:40:59 -08:00
Makefile Linux 6.13-rc6 2025-01-05 14:13:40 -08:00
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.