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Linus Torvalds 9e906a9dea [GIT PULL] perf tools changes for v6.19
Perf event/metric description
 -----------------------------
 Unify all event and metric descriptions in JSON format.
 Now event parsing and handling is greatly simplified by that.
 
 From users point of view, perf list will provide richer
 information about hardware events like the following.
 
     $ perf list hw
 
     List of pre-defined events (to be used in -e or -M):
 
     legacy hardware:
       branch-instructions
            [Retired branch instructions [This event is an alias of branches]. Unit: cpu]
       branch-misses
            [Mispredicted branch instructions. Unit: cpu]
       branches
            [Retired branch instructions [This event is an alias of branch-instructions]. Unit: cpu]
       bus-cycles
            [Bus cycles,which can be different from total cycles. Unit: cpu]
       cache-misses
            [Cache misses. Usually this indicates Last Level Cache misses; this is intended to be used in conjunction with the
             PERF_COUNT_HW_CACHE_REFERENCES event to calculate cache miss rates. Unit: cpu]
       cache-references
            [Cache accesses. Usually this indicates Last Level Cache accesses but this may vary depending on your CPU. This may include
             prefetches and coherency messages; again this depends on the design of your CPU. Unit: cpu]
       cpu-cycles
            [Total cycles. Be wary of what happens during CPU frequency scaling [This event is an alias of cycles]. Unit: cpu]
       cycles
            [Total cycles. Be wary of what happens during CPU frequency scaling [This event is an alias of cpu-cycles]. Unit: cpu]
       instructions
            [Retired instructions. Be careful,these can be affected by various issues,most notably hardware interrupt counts. Unit: cpu]
       ref-cycles
            [Total cycles; not affected by CPU frequency scaling. Unit: cpu]
 
 But most notable changes would be in the perf stat.  On the right side,
 the default metrics are better named and aligned. :)
 
     $ perf stat -- perf test -w noploop
 
      Performance counter stats for 'perf test -w noploop':
 
                     11      context-switches                 #     10.8 cs/sec  cs_per_second
                      0      cpu-migrations                   #      0.0 migrations/sec  migrations_per_second
                  3,612      page-faults                      #   3532.5 faults/sec  page_faults_per_second
               1,022.51 msec task-clock                       #      1.0 CPUs  CPUs_utilized
                110,466      branch-misses                    #      0.0 %  branch_miss_rate         (88.66%)
          6,934,452,104      branches                         #   6781.8 M/sec  branch_frequency     (88.66%)
          4,657,032,590      cpu-cycles                       #      4.6 GHz  cycles_frequency       (88.65%)
         27,755,874,218      instructions                     #      6.0 instructions  insn_per_cycle  (89.03%)
                             TopdownL1                        #      0.3 %  tma_backend_bound
                                                              #      9.3 %  tma_bad_speculation      (89.05%)
                                                              #      9.7 %  tma_frontend_bound       (77.86%)
                                                              #     80.7 %  tma_retiring             (88.81%)
 
            1.025318171 seconds time elapsed
 
            1.013248000 seconds user
            0.012014000 seconds sys
 
 Deferred unwinding support
 --------------------------
 With the kernel support [1], perf can use deferred callchains for
 userspace stack trace with frame pointers like below:
 
     $ perf record --call-graph fp,defer ...
 
 This will be transparent to users when it comes to other commands like
 perf report and perf script.  They will merge the deferred callchains to
 the previous samples as if they were collected together.
 
 [1] https://git.kernel.org/torvalds/c/c69993ecdd4dfde2b7da08b022052a33b203da07
 
 ARM SPE updates
 ---------------
 * Extensive enhancements to support various kinds of memory operations
   including GCS, MTE allocation tags, memcpy/memset, register access,
   and SIMD operations.
 
 * Add inverted data source filter (inv_data_src_filter) support to
   exclude certain data sources.
 
 * Improve documentation.
 
 Vendor event updates
 --------------------
 * Intel: Updated event files for Sierra Forest, Panther Lake, Meteor Lake,
          Lunar Lake, Granite Rapids, and others.
 
 * Arm64: Added metrics for i.MX94 DDR PMU and Cortex-A720AE definitions.
 
 * RISC-V: Added JSON support for T-HEAD C920V2.
 
 Misc
 ----
 * Improve pointer tracking in data type profiling.  It'd give better
   output when the variable is using container_of() to convert type.
 
 * Annotation support for perf c2c report in TUI.  Press 'a' key to
   enter annotation view from cacheline browser window.  This will show
   which instruction is causing the cacheline contention.
 
 * Lots of fixes and test coverage improvements!
 
 Signed-off-by: Namhyung Kim <namhyung@kernel.org>
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Merge tag 'perf-tools-for-v6.19-2025-12-06' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools

Pull perf tools updates from Namhyung Kim:
 "Perf event/metric description:

  Unify all event and metric descriptions in JSON format. Now event
  parsing and handling is greatly simplified by that.

  From users point of view, perf list will provide richer information
  about hardware events like the following.

    $ perf list hw

    List of pre-defined events (to be used in -e or -M):

    legacy hardware:
      branch-instructions
           [Retired branch instructions [This event is an alias of branches]. Unit: cpu]
      branch-misses
           [Mispredicted branch instructions. Unit: cpu]
      branches
           [Retired branch instructions [This event is an alias of branch-instructions]. Unit: cpu]
      bus-cycles
           [Bus cycles,which can be different from total cycles. Unit: cpu]
      cache-misses
           [Cache misses. Usually this indicates Last Level Cache misses; this is intended to be used in conjunction with the
            PERF_COUNT_HW_CACHE_REFERENCES event to calculate cache miss rates. Unit: cpu]
      cache-references
           [Cache accesses. Usually this indicates Last Level Cache accesses but this may vary depending on your CPU. This may include
            prefetches and coherency messages; again this depends on the design of your CPU. Unit: cpu]
      cpu-cycles
           [Total cycles. Be wary of what happens during CPU frequency scaling [This event is an alias of cycles]. Unit: cpu]
      cycles
           [Total cycles. Be wary of what happens during CPU frequency scaling [This event is an alias of cpu-cycles]. Unit: cpu]
      instructions
           [Retired instructions. Be careful,these can be affected by various issues,most notably hardware interrupt counts. Unit: cpu]
      ref-cycles
           [Total cycles; not affected by CPU frequency scaling. Unit: cpu]

  But most notable changes would be in the perf stat. On the right side,
  the default metrics are better named and aligned. :)

    $ perf stat -- perf test -w noploop

     Performance counter stats for 'perf test -w noploop':

                    11      context-switches                 #     10.8 cs/sec  cs_per_second
                     0      cpu-migrations                   #      0.0 migrations/sec  migrations_per_second
                 3,612      page-faults                      #   3532.5 faults/sec  page_faults_per_second
              1,022.51 msec task-clock                       #      1.0 CPUs  CPUs_utilized
               110,466      branch-misses                    #      0.0 %  branch_miss_rate         (88.66%)
         6,934,452,104      branches                         #   6781.8 M/sec  branch_frequency     (88.66%)
         4,657,032,590      cpu-cycles                       #      4.6 GHz  cycles_frequency       (88.65%)
        27,755,874,218      instructions                     #      6.0 instructions  insn_per_cycle  (89.03%)
                            TopdownL1                        #      0.3 %  tma_backend_bound
                                                             #      9.3 %  tma_bad_speculation      (89.05%)
                                                             #      9.7 %  tma_frontend_bound       (77.86%)
                                                             #     80.7 %  tma_retiring             (88.81%)

           1.025318171 seconds time elapsed

           1.013248000 seconds user
           0.012014000 seconds sys

  Deferred unwinding support:

  With the kernel support (commit c69993ecdd4d: "perf: Support deferred
  user unwind"), perf can use deferred callchains for userspace stack
  trace with frame pointers like below:

    $ perf record --call-graph fp,defer ...

  This will be transparent to users when it comes to other commands like
  perf report and perf script. They will merge the deferred callchains
  to the previous samples as if they were collected together.

  ARM SPE updates

   - Extensive enhancements to support various kinds of memory
     operations including GCS, MTE allocation tags, memcpy/memset,
     register access, and SIMD operations.

   - Add inverted data source filter (inv_data_src_filter) support to
     exclude certain data sources.

   - Improve documentation.

  Vendor event updates:

   - Intel: Updated event files for Sierra Forest, Panther Lake, Meteor
     Lake, Lunar Lake, Granite Rapids, and others.

   - Arm64: Added metrics for i.MX94 DDR PMU and Cortex-A720AE
     definitions.

   - RISC-V: Added JSON support for T-HEAD C920V2.

  Misc:

   - Improve pointer tracking in data type profiling. It'd give better
     output when the variable is using container_of() to convert type.

   - Annotation support for perf c2c report in TUI. Press 'a' key to
     enter annotation view from cacheline browser window. This will show
     which instruction is causing the cacheline contention.

   - Lots of fixes and test coverage improvements!"

* tag 'perf-tools-for-v6.19-2025-12-06' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools: (214 commits)
  libperf: Use 'extern' in LIBPERF_API visibility macro
  perf stat: Improve handling of termination by signal
  perf tests stat: Add test for error for an offline CPU
  perf stat: When no events, don't report an error if there is none
  perf tests stat: Add "--null" coverage
  perf cpumap: Add "any" CPU handling to cpu_map__snprint_mask
  libperf cpumap: Fix perf_cpu_map__max for an empty/NULL map
  perf stat: Allow no events to open if this is a "--null" run
  perf test kvm: Add some basic perf kvm test coverage
  perf tests evlist: Add basic evlist test
  perf tests script dlfilter: Add a dlfilter test
  perf tests kallsyms: Add basic kallsyms test
  perf tests timechart: Add a perf timechart test
  perf tests top: Add basic perf top coverage test
  perf tests buildid: Add purge and remove testing
  perf tests c2c: Add a basic c2c
  perf c2c: Clean up some defensive gets and make asan clean
  perf jitdump: Fix missed dso__put
  perf mem-events: Don't leak online CPU map
  perf hist: In init, ensure mem_info is put on error paths
  ...
2025-12-07 07:07:02 -08:00
arch TTY/Serial changes for 6.19-rc1 2025-12-06 18:38:19 -08:00
block VFIO updates for v6.19-rc1 2025-12-04 18:42:48 -08:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto Networking changes for 6.19. 2025-12-03 17:24:33 -08:00
Documentation USB/Thunderbolt changes for 6.19-rc1 2025-12-06 18:42:12 -08:00
drivers Staging driver updates for 6.19-rc1 2025-12-06 18:52:00 -08:00
fs ocfs2: fix xattr array entry __counted_by error 2025-12-06 15:28:11 -08:00
include Staging driver updates for 6.19-rc1 2025-12-06 18:52:00 -08:00
init Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
io_uring Significant patch series in this merge are as follows: 2025-12-05 13:52:43 -08:00
ipc Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
kernel Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
lib fbdev fixes & enhancements for 6.19-rc1: 2025-12-06 15:41:26 -08:00
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 Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
net NFSD 6.19 Release Notes 2025-12-06 10:57:02 -08:00
rust USB/Thunderbolt changes for 6.19-rc1 2025-12-06 18:42:12 -08:00
samples USB/Thunderbolt changes for 6.19-rc1 2025-12-06 18:42:12 -08:00
scripts Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
security Landlock update for v6.19-rc1 2025-12-06 09:52:41 -08:00
sound bitmap updates for v6.19 2025-12-06 09:01:27 -08:00
tools [GIT PULL] perf tools changes for v6.19 2025-12-07 07:07:02 -08:00
usr initramfs: add gen_init_cpio to hostprogs unconditionally 2025-11-26 21:55:40 +01:00
virt soc: driver updates for 6.19 2025-12-05 17:29:04 -08:00
.clang-format Significant patch series in this merge are as follows: 2025-12-05 13:52:43 -08:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: kbuild: add proc macro library support 2025-11-24 17:15:36 +01:00
.mailmap Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
.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 CREDITS: update Martin's information 2025-11-12 10:00:14 -08:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Staging driver updates for 6.19-rc1 2025-12-06 18:52:00 -08:00
Makefile Detect unused tracepoints for v6.19: 2025-12-05 09:37:41 -08:00
README README: restructure with role-based documentation and guidelines 2025-11-29 08:40:33 -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


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



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