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Mykyta Yatsenko 84f7a49e76 selftests/bpf: Add resizable hashmap to benchmarks
Support resizable hashmap in BPF map benchmarks.

1. LOOKUP  (single producer, M events/sec)

  key | max | nr    |    htab |   rhtab | ratio | delta
  ----+-----+-------+---------+---------+-------+-------
    8 |  1K |   750 |   99.85 |   81.92 | 0.82x |  -18 %
    8 |  1K |    1K |  100.71 |   80.19 | 0.80x |  -20 %
    8 |  1M |  750K |   23.37 |   72.09 | 3.08x | +208 %
    8 |  1M |    1M |   13.39 |   53.72 | 4.01x | +301 %
   32 |  1K |   750 |   51.57 |   42.78 | 0.83x |  -17 %
   32 |  1K |    1K |   50.81 |   45.83 | 0.90x |  -10 %
   32 |  1M |  750K |   11.27 |   15.29 | 1.36x |  +36 %
   32 |  1M |    1M |    7.32 |    8.75 | 1.19x |  +19 %
  256 |  1K |   750 |    7.58 |    7.88 | 1.04x |   +4 %
  256 |  1K |    1K |    7.43 |    7.81 | 1.05x |   +5 %
  256 |  1M |  750K |    3.69 |    4.27 | 1.16x |  +16 %
  256 |  1M |    1M |    2.60 |    3.12 | 1.20x |  +20 %

Pattern:
  * Small map (1K): htab wins for 8 / 32 byte keys by 10-20%
  * Large map (1M): rhtab wins everywhere, up to 4x at high load
    factor with 8 byte keys.
  * Higher load factor amplifies rhtab's lead: rhtab grows the
    bucket array; htab stays at user-declared max.

2. FULL UPDATE  (M events/sec per producer)

  htab  per-producer:
    20.33   22.02   19.27   23.61   24.18   23.17   21.07
    mean  21.94   range  19.27 - 24.18

  rhtab per-producer:
   133.51  129.47   74.52  129.29  102.26  129.98  107.64
    mean 115.24   range  74.52 - 133.51

  speedup (mean): 5.25x   (+425 %)

In-place memcpy avoids the per-update alloc + RCU pointer swap
that htab pays.

3. MEMORY

  value_size |  htab ops/s | rhtab ops/s | htab mem | rhtab mem
  -----------+-------------+-------------+----------+----------
       32 B  |  122.87 k/s |  133.04 k/s | 2.47 MiB | 2.49 MiB
     4096 B  |   64.43 k/s |   65.38 k/s | 6.74 MiB | 6.44 MiB
  rhtab/htab :  +8 % ops, +0.8 % mem   (32 B)
                +1 % ops,  -4  % mem (4096 B)

Throughput effectively tied

SUMMARY

  * Small / well-fitting map: htab is faster (cache-friendly
    fixed bucket array), but only by ~10-20 %.
  * Large / high-load-factor map: rhtab is dramatically faster
    (1.2x to 4x) because rhashtable resizes to keep the load
    factor sane while htab stays stuck at user-declared max.
  * Update-heavy workloads: rhtab is ~5x faster per producer
    via in-place memcpy.
  * Memory benchmark: effectively on par.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Link: https://lore.kernel.org/r/20260605-rhash-v7-12-5b8e05f8630d@meta.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-06-05 08:00:08 -07:00
arch bpf, arm64: Fix redundant MOV and clarify stack arg comments 2026-05-31 17:49:21 -07:00
block cgroup: Fixes for v7.1-rc4 2026-05-22 16:28:47 -07:00
certs Clang build fixes for 7.1 2026-04-24 09:29:51 -07:00
crypto crypto/krb5, rxrpc: Fix lack of pre-decrypt/pre-verify length checks 2026-05-20 16:36:45 -07:00
Documentation Merge branch 'arena_direct_access' 2026-05-25 08:35:48 -07:00
drivers Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 7.1-rc5 2026-05-25 06:33:30 -07:00
fs Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 7.1-rc5 2026-05-25 06:33:30 -07:00
include bpf: Implement resizable hashmap basic functions 2026-06-05 08:00:08 -07:00
init memblock: updates for 7.0-rc1 2026-04-18 11:29:14 -07:00
io_uring io_uring-7.1-20260522 2026-05-22 11:53:28 -07:00
ipc Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kernel bpf: Optimize word-sized keys for resizable hashtable 2026-06-05 08:00:08 -07:00
lib rhashtable: Add selftest for rhashtable_next_key() 2026-06-05 08:00:07 -07:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm cgroup: Fixes for v7.1-rc4 2026-05-22 16:28:47 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 7.1-rc5 2026-05-25 06:33:30 -07:00
rust Rust fixes for v7.1 2026-05-09 11:24:02 -07:00
samples soc: drivers for 7.1 2026-04-16 20:34:34 -07:00
scripts Second round of Kbuild fixes for 7.1 2026-05-19 09:43:24 -07:00
security lsm/stable-7.1 PR 20260519 2026-05-19 15:31:35 -05:00
sound ASoC: Fixes for v7.1 2026-05-22 08:25:18 +02:00
tools selftests/bpf: Add resizable hashmap to benchmarks 2026-06-05 08:00:08 -07:00
usr kbuild: uapi: also test UAPI headers against C++ compilers 2026-03-25 13:24:42 +01:00
virt KVM: Reject wrapped offset in kvm_reset_dirty_gfn() 2026-05-12 22:16:16 +02:00
.clang-format Devicetree updates for v7.0: 2026-02-11 18:27:08 -08:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add Askar 2026-04-15 02:15:02 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rust: provide an option to inline C helpers into Rust 2026-03-30 02:03:52 +02:00
.mailmap Including fixes from Bluetooth, wireless and netfilter. 2026-05-21 14:39:12 -07:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -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 Delete some obsolete networking code 2026-04-24 09:41:58 -07:00
Kbuild checksyscalls: move instance functionality into generic code 2026-04-05 09:21:32 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS bpf: Update bpf maintainers 2026-05-31 17:46:25 -07:00
Makefile Linux 7.1-rc5 2026-05-24 13:48:06 -07:00
README docs: add AI Coding Assistants documentation 2026-01-06 14:55:06 -07:00

Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer - Getting started with kernel development
* Academic Researcher - Studying kernel internals and architecture
* Security Expert - Hardening and vulnerability analysis
* Backport/Maintenance Engineer - Maintaining stable kernels
* System Administrator - Configuring and troubleshooting
* Maintainer - Leading subsystems and reviewing patches
* Hardware Vendor - Writing drivers for new hardware
* Distribution Maintainer - Packaging kernels for distros
* AI Coding Assistant - LLMs and AI-powered development tools


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
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