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Kuan-Wei Chiu c641722e0c lib min_heap: optimize number of comparisons in min_heapify()
Optimize the min_heapify() function, resulting in a significant reduction
of approximately 50% in the number of comparisons for large random inputs,
while maintaining identical results.

The current implementation performs two comparisons per level to identify
the minimum among three elements.  In contrast, the proposed bottom-up
variation uses only one comparison per level to assess two children until
reaching the leaves.  Then, it sifts up until the correct position is
determined.

Typically, the process of sifting down proceeds to the leaf level,
resulting in O(1) secondary comparisons instead of log2(n).  This
optimization significantly reduces the number of costly indirect function
calls and improves overall performance.

Link: https://lkml.kernel.org/r/20240110081213.2289636-3-visitorckw@gmail.com
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-02-22 15:38:52 -08:00
arch treewide: update LLVM Bugzilla links 2024-02-22 15:38:51 -08:00
block blk-iocost: Fix an UBSAN shift-out-of-bounds warning 2024-02-08 10:11:39 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto treewide: update LLVM Bugzilla links 2024-02-22 15:38:51 -08:00
Documentation Kbuild fixes for v6.8 (2nd) 2024-02-18 10:09:25 -08:00
drivers bcache: use of hlist_count_nodes() 2024-02-22 15:38:51 -08:00
fs ocfs2: spelling fix 2024-02-22 15:38:51 -08:00
include lib min_heap: optimize number of comparisons in min_heapify() 2024-02-22 15:38:52 -08:00
init update workarounds for gcc "asm goto" issue 2024-02-15 11:14:33 -08:00
io_uring io_uring/net: fix multishot accept overflow handling 2024-02-14 18:30:19 -07:00
ipc shm: Slim down dependencies 2023-12-20 19:26:31 -05:00
kernel panic: suppress gnu_printf warning 2024-02-22 15:38:51 -08:00
lib treewide: update LLVM Bugzilla links 2024-02-22 15:38:51 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm treewide: update LLVM Bugzilla links 2024-02-22 15:38:51 -08:00
net treewide: update LLVM Bugzilla links 2024-02-22 15:38:51 -08:00
rust Rust changes for v6.8 2024-01-11 13:05:41 -08:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-09 15:57:48 -08:00
scripts kallsyms: ignore ARMv4 thunks along with others 2024-02-15 22:44:56 +09:00
security treewide: update LLVM Bugzilla links 2024-02-22 15:38:51 -08:00
sound ALSA: usb-audio: More relaxed check of MIDI jack names 2024-02-15 16:56:05 +01:00
tools selftests: add eventfd selftests 2024-02-22 15:38:51 -08:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt Generic: 2024-01-17 13:03:37 -08:00
.clang-format clang-format: Update with v6.7-rc4's for_each macro list 2023-12-08 23:54:38 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.mailmap Including fixes from can, wireless and netfilter. 2024-02-15 11:39:27 -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 MAINTAINERS: supplement of zswap maintainers update 2024-01-25 23:52:21 -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 Driver core fixes for 6.8-rc5 2024-02-17 08:56:41 -08:00
Makefile Linux 6.8-rc5 2024-02-18 12:56:25 -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.