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Andrea Righi 29f512f555 sched_ext: idle: Extend topology optimizations to all tasks
The built-in idle selection policy, scx_select_cpu_dfl(), always
prioritizes picking idle CPUs within the same LLC or NUMA node, but
these optimizations are currently applied only when a task has no CPU
affinity constraints.

This is done primarily for efficiency, as it avoids the overhead of
updating a cpumask every time we need to select an idle CPU (which can
be costly in large SMP systems).

However, this approach limits the effectiveness of the built-in idle
policy and results in inconsistent behavior, as affinity-restricted
tasks don't benefit from topology-aware optimizations.

To address this, modify the policy to apply LLC and NUMA-aware
optimizations even when a task is constrained to a subset of CPUs.

We can still avoid updating the cpumasks by checking if the subset of
LLC and node CPUs are contained in the subset of allowed CPUs usable by
the task (which is true in most of the cases - for tasks that don't have
affinity constratints).

Moreover, use temporary local per-CPU cpumasks to determine the LLC and
node subsets, minimizing potential overhead even on large SMP systems.

Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
History 2025-04-07 07:13:52 -10:00
arch RISC-V Patches for the 6.15 Merge Window, Part 1 2025-04-04 09:49:17 -07:00
block block: don't grab elevator lock during queue initialization 2025-04-03 08:32:03 -06:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push fixes reverts the multibuffer hash testing as it is buggy. 2025-04-02 09:14:59 -07:00
Documentation RISC-V Patches for the 6.15 Merge Window, Part 1 2025-04-04 09:49:17 -07:00
drivers RISC-V Patches for the 6.15 Merge Window, Part 1 2025-04-04 09:49:17 -07:00
fs 4 ksmbd SMB3 server fixes, all also for stable 2025-04-03 16:18:06 -07:00
include RISC-V Patches for the 6.15 Merge Window, Part 1 2025-04-04 09:49:17 -07:00
init ARM and clkdev updates for 6.15-rc1 2025-04-03 12:21:44 -07:00
io_uring io_uring: always do atomic put from iowq 2025-04-03 08:31:57 -06:00
ipc treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
kernel sched_ext: idle: Extend topology optimizations to all tasks 2025-04-07 07:13:52 -10:00
lib One bugfix and a couple of small late-arriving updates. 2025-04-03 11:16:57 -07:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm - The 2 patch series "mm: fixes for fallouts from mem_init() cleanup" 2025-04-03 11:10:00 -07:00
net Including fixes from netfilter. 2025-04-04 09:15:35 -07:00
rust ARM and clkdev updates for 6.15-rc1 2025-04-03 12:21:44 -07:00
samples tracing fixes for 6.15 2025-04-03 09:52:44 -07:00
scripts ARM and clkdev updates for 6.15-rc1 2025-04-03 12:21:44 -07:00
security mseal sysmap: kernel config and header change 2025-04-01 15:17:14 -07:00
sound sound fixes for 6.15-rc1 2025-04-04 07:05:33 -07:00
tools sched_ext: Drop "ops" from scx_ops_bypass(), scx_ops_breather() and friends 2025-04-04 08:52:49 -10:00
usr kbuild: hdrcheck: fix cross build with clang 2025-03-05 04:06:45 +09:00
virt ARM: 2025-03-25 14:22:07 -07:00
.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: give Clippy the minimum supported Rust version 2025-01-10 00:17:25 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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 rust: use host dylib naming convention to support macOS 2025-01-10 01:01:24 +01:00
.mailmap mailmap: add an entry for Nicolas Schier 2025-04-01 15:20:45 -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 Including fixes from netfilter. 2025-04-04 09:15:35 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Including fixes from netfilter. 2025-04-04 09:15:35 -07:00
Makefile [ Merge note: this pull request depends on you having merged 2025-03-24 22:06:11 -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.