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473f6c8f |
| 22-Aug-2026 |
Linus Torvalds <torvalds@linux-foundation.org> |
Merge tag 'perf-tools-for-v7.3-2026-08-21' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools
Pull perf tools updates from Namhyung Kim: "perf c2c:
- Add 'function view' in perf c
Merge tag 'perf-tools-for-v7.3-2026-08-21' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools
Pull perf tools updates from Namhyung Kim: "perf c2c:
- Add 'function view' in perf c2c report TUI (switched by pressing 'TAB' in the cacheline view) to organize samples around functions rather than cachelines in 3-level hierarchy:
Level 1: Read-side function (sorted by estimated Cycles %) Level 2: Contending writer functions (sorted by Store count) Level 3: Shared cacheline addresses
Users can navigate the entries and fold/unfold using 'e' key. An example output would look like below:
Shared Data Functions Table (19 entries, sorted on Cycles %) Cycles Store % count Function / Contending function / Cacheline ---------------------------------------------------------------------- + 35.67% 876 + [k] cpupri_set + 24.31% 424 + [k] pull_rt_task - 16.53% 555 - [k] dequeue_pushable_task 145 - [k] pull_rt_task 145 0xff2d0082809da080 139 - [k] enqueue_pushable_task 70 0xff2d00a2071f9640 69 0xff2d0082809da000
python module support:
- Extend "perf" python module so that it can be fully functional. The goal is to run scripts directly, not by 'perf script' command. This would give better performance as well as more control to build standalone programs with UI.
- Add LiveSession helper (perf_live.py) to enable live event collection directly from Python using perf.evlist and perf.parse_events.
perf stat:
- Add --hide-zero-events option to suppress zero-count events - Reject conflicting --field-separator and --json-output options - Fix duplicate event output with --for-each-cgroup
perf sched latency:
- Add -H/--histogram and --hist-mode (log|linear) options to show scheduler wait latency histograms - Add --time option to filter analysis by time span in 'perf sched latency'
ARM CoreSight:
- Synthesize callchains for instruction samples from CoreSight trace using thread stack ('--itrace=g...') - Support call indentation ('perf script -F +callindent') to display call depth hierarchy on branch samples - Decode ETE (Embedded Trace Extension) exception packets
Build system:
- Add 'make install-build-deps' target to install required packages - Parallelize JSON and metric pre-computation in jevents.py for faster builds
Vendor event/metric updates:
- Add Intel Nova Lake events and update tables for existing models - Update AMD Zen 5 and Zen 6 core events - Update Arm64 Tegra410 metrics and PowerPC hcalls
Internal changes and fixes:
- Harden trace-event and synthetic event parsing against corrupted data - Fix unwinding of multi-threaded processes in libdw unwinder - Fix memory leaks in various commands and python bindings - Speed up 'perf test' shell tests"
* tag 'perf-tools-for-v7.3-2026-08-21' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools: (232 commits) perf vendor events arm64: Fix Tegra410 Olympus event 0x0197 perf vendor events arm64: fix swapped MetricGroup for Tegra410 L1 prefetcher metrics perf evlist: Warn when 'sleep' workload is used without system-wide (-a) option perf c2c: document function view in perf-c2c man page perf c2c: add function view browser UI and cacheline detail perf c2c: build and finalize the function view hierarchy perf c2c: add function view hierarchy entry creation perf c2c: add function view stats merge and memory management perf c2c: add HPP list parsing for function view columns perf c2c: add column rendering for function view perf c2c: add function view model skeleton perf c2c: extract shared data structures into util/c2c.h perf test sample-parsing: Validate PERF_FORMAT_GROUP values without LOST perf dso: Replace assert with runtime check in dso__read_symbol() perf dso: Guard against cache underflow on short reads in dso_cache__memcpy() perf dso: Use stored fd error instead of stale errno in file_read() and file_size() perf dso: Guard close() against invalid fd in dso__decompress_kmodule_path() perf dso: Guard against errno==0 when dso__get_filename() returns NULL perf build: install-build-deps: add RHEL family devel package mapping perf build: Remove leftover feature tests for removed cxx and clang support ...
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| #
f2effca1 |
| 24-Jul-2026 |
Alessio Podda <aleph.pi.gh@gmail.com> |
perf unwind-libdw: Fix unwinding of multi-threaded processes
The libdw callback API has two levels: dwfl_getthread_frames() first finds the requested thread using the next_thread() or get_thread() c
perf unwind-libdw: Fix unwinding of multi-threaded processes
The libdw callback API has two levels: dwfl_getthread_frames() first finds the requested thread using the next_thread() or get_thread() callback and then walks its stack.
Since perf only has a snapshot of the stack of a single thread, it provides a stubbed-out API that always returns the pid the Dwfl was attached with (i.e. whatever was passed to dwfl_attach_state()), rather than the actual sampled thread's TID.
Commit 6b2658b3f36a ("perf unwind-libdw: Don't discard loaded ELF/DWARF after every unwind") changed libdw unwinding from recreating the Dwfl object for each sample to caching it in struct maps, which is shared by every thread in the process. It left next_thread() unchanged.
Since the pid passed to dwfl_attach_state() is only set at creation, only the thread of the first sample is ever found. As a result, dwfl_getthread_frames() fails with ESRCH when asked to unwind a sample from another thread.
Make next_thread() return the current sample's TID, provide get_thread() so libdw can find it directly, and pass the process PID expected by dwfl_attach_state(). This allows libdw to unwind samples from every thread in a multi-threaded process.
Add a shell regression test that records a four-thread workload and verifies that libdw recovers the worker callchain for every worker TID.
Fixes: 6b2658b3f36a ("perf unwind-libdw: Don't discard loaded ELF/DWARF after every unwind") Assisted-by: Codex:gpt-5.6-sol Signed-off-by: Alessio Podda <aleph.pi.gh@gmail.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
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