Linus Torvalds df8f6181ab Merge tag 'perf-tools-for-v7.1-2026-04-17' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools
Pull perf tools updates from Namhyung Kim:
 "perf report:

   - Add 'comm_nodigit' sort key to combine similar threads that only
     have different numbers in the comm. In the following example, the
     'comm_nodigit' will have samples from all threads starting with
     "bpfrb/" into an entry "bpfrb/<N>".

        $ perf report -s comm_nodigit,comm -H
        ...
        #
        #    Overhead  CommandNoDigit / Command
        # ...........  ........................
        #
            20.30%     swapper
               20.30%     swapper
            13.37%     chrome
               13.37%     chrome
            10.07%     bpfrb/<N>
                7.47%     bpfrb/0
                0.70%     bpfrb/1
                0.47%     bpfrb/3
                0.46%     bpfrb/2
                0.25%     bpfrb/4
                0.23%     bpfrb/5
                0.20%     bpfrb/6
                0.14%     bpfrb/10
                0.07%     bpfrb/7

   - Support flat layout for symfs. The --symfs option is to specify the
     location of debugging symbol files. The default 'hierarchy' layout
     would search the symbol file using the same path of the original
     file under the symfs root. The new 'flat' layout would search only
     in the root directory.

   - Update 'simd' sort key for ARM SIMD flags to cover ASE/SME and more
     predicate flags.

  perf stat:

   - Add --pmu-filter option to select specific PMUs. This would be
     useful when you measure metrics from multiple instance of uncore
     PMUs with similar names.

        # perf stat -M cpa_p0_avg_bw
         Performance counter stats for 'system wide':

            19,417,779,115      hisi_sicl0_cpa0/cpa_cycles/      #     0.00 cpa_p0_avg_bw
                         0      hisi_sicl0_cpa0/cpa_p0_wr_dat/
                         0      hisi_sicl0_cpa0/cpa_p0_rd_dat_64b/
                         0      hisi_sicl0_cpa0/cpa_p0_rd_dat_32b/
            19,417,751,103      hisi_sicl10_cpa0/cpa_cycles/     #     0.00 cpa_p0_avg_bw
                         0      hisi_sicl10_cpa0/cpa_p0_wr_dat/
                         0      hisi_sicl10_cpa0/cpa_p0_rd_dat_64b/
                         0      hisi_sicl10_cpa0/cpa_p0_rd_dat_32b/
            19,417,730,679      hisi_sicl2_cpa0/cpa_cycles/      #     0.31 cpa_p0_avg_bw
                75,635,749      hisi_sicl2_cpa0/cpa_p0_wr_dat/
                18,520,640      hisi_sicl2_cpa0/cpa_p0_rd_dat_64b/
                         0      hisi_sicl2_cpa0/cpa_p0_rd_dat_32b/
            19,417,674,227      hisi_sicl8_cpa0/cpa_cycles/      #     0.00 cpa_p0_avg_bw
                         0      hisi_sicl8_cpa0/cpa_p0_wr_dat/
                         0      hisi_sicl8_cpa0/cpa_p0_rd_dat_64b/
                         0      hisi_sicl8_cpa0/cpa_p0_rd_dat_32b/

              19.417734480 seconds time elapsed

     With --pmu-filter, users can select only hisi_sicl2_cpa0 PMU.

        # perf stat --pmu-filter hisi_sicl2_cpa0 -M cpa_p0_avg_bw
         Performance counter stats for 'system wide':

             6,234,093,559      cpa_cycles                       #     0.60 cpa_p0_avg_bw
                50,548,465      cpa_p0_wr_dat
                 7,552,182      cpa_p0_rd_dat_64b
                         0      cpa_p0_rd_dat_32b

               6.234139320 seconds time elapsed

  Data type profiling:

   - Quality improvements by tracking register state more precisely

   - Ensure array members to get the type

   - Handle more cases for global variables

  Vendor event/metric updates:

   - Update various Intel events and metrics

   - Add NVIDIA Tegra 410 Olympus events

  Internal changes:

   - Verify perf.data header for maliciously crafted files

   - Update perf test to cover more usages and make them robust

   - Move a couple of copied kernel headers not to annoy objtool build

   - Fix a bug in map sorting in name order

   - Remove some unused codes

  Misc:

   - Fix module symbol resolution with non-zero text address

   - Add -t/--threads option to `perf bench mem mmap`

   - Track duration of exit*() syscall by `perf trace -s`

   - Add core.addr2line-timeout and core.addr2line-disable-warn config
     items"

* tag 'perf-tools-for-v7.1-2026-04-17' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools: (131 commits)
  perf loongarch: Fix build failure with CONFIG_LIBDW_DWARF_UNWIND
  perf annotate: Use jump__delete when freeing LoongArch jumps
  perf test: Fixes for check branch stack sampling
  perf test: Fix inet_pton probe failure and unroll call graph
  perf build: fix "argument list too long" in second location
  perf header: Add sanity checks to HEADER_BPF_BTF processing
  perf header: Sanity check HEADER_BPF_PROG_INFO
  perf header: Sanity check HEADER_PMU_CAPS
  perf header: Sanity check HEADER_HYBRID_TOPOLOGY
  perf header: Sanity check HEADER_CACHE
  perf header: Sanity check HEADER_GROUP_DESC
  perf header: Sanity check HEADER_PMU_MAPPINGS
  perf header: Sanity check HEADER_MEM_TOPOLOGY
  perf header: Sanity check HEADER_NUMA_TOPOLOGY
  perf header: Sanity check HEADER_CPU_TOPOLOGY
  perf header: Sanity check HEADER_NRCPUS and HEADER_CPU_DOMAIN_INFO
  perf header: Bump up the max number of command line args allowed
  perf header: Validate nr_domains when reading HEADER_CPU_DOMAIN_INFO
  perf sample: Fix documentation typo
  perf arm_spe: Improve SIMD flags setting
  ...
2026-04-18 09:24:56 -07:00
2026-01-26 19:07:09 -08:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -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/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst
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