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Chunhai Guo 0f6273ab46 erofs: add a reserved buffer pool for lz4 decompression
This adds a special global buffer pool (in the end) for reserved pages.

Using a reserved pool for LZ4 decompression significantly reduces the
time spent on extra temporary page allocation for the extreme cases in
low memory scenarios.

The table below shows the reduction in time spent on page allocation for
LZ4 decompression when using a reserved pool. The results were obtained
from multi-app launch benchmarks on ARM64 Android devices running the
5.15 kernel with an 8-core CPU and 8GB of memory. In the benchmark, we
launched 16 frequently-used apps, and the camera app was the last one in
each round. The data in the table is the average time of camera app for
each round.

After using the reserved pool, there was an average improvement of 150ms
in the overall launch time of our camera app, which was obtained from
the systrace log.

+--------------+---------------+--------------+---------+
|              | w/o page pool | w/ page pool |  diff   |
+--------------+---------------+--------------+---------+
| Average (ms) |     3434      |      21      | -99.38% |
+--------------+---------------+--------------+---------+

Based on the benchmark logs, 64 pages are sufficient for 95% of
scenarios. This value can be adjusted with a module parameter
`reserved_pages`. The default value is 0.

This pool is currently only used for the LZ4 decompressor, but it can be
applied to more decompressors if needed.

Signed-off-by: Chunhai Guo <guochunhai@vivo.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240402131523.2703948-1-guochunhai@vivo.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2024-05-08 17:12:51 +08:00
arch powerpc fixes for 6.9 #4 2024-05-05 10:44:04 -07:00
block vfs-6.9-rc6.fixes 2024-04-26 11:01:28 -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 Char/Misc driver fixes for 6.9-rc7 2024-05-05 10:08:52 -07:00
drivers - Fix error logging and check user-supplied data when injecting an error 2024-05-05 10:51:29 -07:00
fs erofs: add a reserved buffer pool for lz4 decompression 2024-05-08 17:12:51 +08:00
include tracing and tracefs fixes for v6.9 2024-05-05 09:53:09 -07:00
init Rust fixes for v6.9 2024-04-27 12:11:55 -07:00
io_uring io_uring/net: restore msg_control on sendzc retry 2024-04-08 21:48:41 -06:00
ipc sysctl changes for v6.9-rc1 2024-03-18 14:59:13 -07:00
kernel Fix suspicious RCU usage in __do_softirq(). 2024-05-05 10:12:32 -07:00
lib Char/Misc driver fixes for 6.9-rc7 2024-05-05 10:08:52 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/hugetlb: fix DEBUG_LOCKS_WARN_ON(1) when dissolve_free_hugetlb_folio() 2024-04-25 10:07:27 -07:00
net Including fixes from bpf. 2024-05-02 08:51:47 -07:00
rust rust: remove params from module macro example 2024-04-25 17:34:33 +02:00
samples Tracing updates for 6.9: 2024-03-18 15:11:44 -07:00
scripts Rust fixes for v6.9 2024-04-27 12:11:55 -07:00
security security: Place security_path_post_mknod() where the original IMA call was 2024-04-03 10:21:32 -07:00
sound ALSA: hda/realtek: Fix build error without CONFIG_PM 2024-05-02 08:25:06 +02:00
tools cxl fix for v6.9-rc7 2024-05-03 16:21:05 -07:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt KVM: Drop unused @may_block param from gfn_to_pfn_cache_invalidate_start() 2024-04-11 12:58:53 -07:00
.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 bpf-for-netdev 2024-04-26 17:36:53 -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 Including fixes from bpf. 2024-05-02 08:51:47 -07:00
Makefile Linux 6.9-rc7 2024-05-05 14:06:01 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -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 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.