kernel/linux.git/Documentation/tools/rtla, branch master

Merge tag 'trace-rtla-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2026-04-16T00:48:24+00:00

Pull RTLA updates from Steven Rostedt: - Simplify option parsing Auto-generate getopt_long() optstring for short options from long options array, avoiding the need to specify it manually and reducing the surface for mistakes. - Add unit tests Implement unit tests (make unit-tests) using libcheck, next to existing runtime tests (make check). Currently, three functions from utils.c are tested. - Add --stack-format option In addition to stopping stack pointer decoding (with -s/--stack option) on first unresolvable pointer, allow also skipping unresolvable pointers and displaying everything, configurable with a new option. - Unify number of CPUs into one global variable Use one global variable, nr_cpus, to store the number of CPUs instead of retrieving it and passing it at multiple places. - Fix behavior in various corner cases Make RTLA behave correctly in several corner cases: memory allocation failure, invalid value read from kernel side, thread creation failure, malformed time value input, and read/write failure or interruption by signal. - Improve string handling Simplify several places in the code that handle strings, including parsing of action arguments. A few new helper functions and variables are added for that purpose. - Get rid of magic numbers Few places handling paths use a magic number of 1024. Replace it with MAX_PATH and ARRAY_SIZE() macro. - Unify threshold handling Code that handles response to latency threshold is duplicated between tools, which has led to bugs in the past. Unify it into a new helper as much as possible. - Fix segfault on SIGINT during cleanup The SIGINT handler touches dynamically allocated memory. Detach it before freeing it during cleanup to prevent segmentation fault and discarding of output buffers. Also, properly document SIGINT handling while at it. * tag 'trace-rtla-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (28 commits) Documentation/rtla: Document SIGINT behavior rtla: Fix segfault on multiple SIGINTs rtla/utils: Fix loop condition in PID validation rtla/utils: Fix resource leak in set_comm_sched_attr() rtla/trace: Fix I/O handling in save_trace_to_file() rtla/trace: Fix write loop in trace_event_save_hist() rtla/timerlat: Simplify RTLA_NO_BPF environment variable check rtla: Use str_has_prefix() for option prefix check rtla: Enforce exact match for time unit suffixes rtla: Use str_has_prefix() for prefix checks rtla: Add str_has_prefix() helper function rtla: Handle pthread_create() failure properly rtla/timerlat: Add bounds check for softirq vector rtla: Simplify code by caching string lengths rtla: Replace magic number with MAX_PATH rtla: Introduce common_threshold_handler() helper rtla/actions: Simplify argument parsing rtla: Use strdup() to simplify code rtla: Exit on memory allocation failures during initialization tools/rtla: Remove unneeded nr_cpus from for_each_monitored_cpu ...

Documentation/rtla: Convert links to RST format

2026-04-09T14:23:12+00:00

Web links in the documentation are not properly displayed. In the man pages web links look like: Osnoise tracer documentation: < > On web pages the URL caption is the URL itself. Convert tracer documentation links to RST anonymous hyperlink format for better rendering. Use newer docs.kernel.org instead of www.kernel.org/doc/html/latest for brevity. After the change, the links in the man pages look like: Osnoise tracer On web pages the captions are the titles of the links. Signed-off-by: Costa Shulyupin Signed-off-by: Jonathan Corbet Message-ID: <20260405163847.3337981-1-costa.shul@redhat.com>

Documentation/rtla: Document SIGINT behavior

2026-03-27T09:58:30+00:00

The behavior of RTLA on receiving SIGINT is currently undocumented. Describe it in RTLA's common appendix that appears in man pages for all RTLA tools to avoid confusion. Suggested-by: Attila Fazekas Reviewed-by: Steven Rostedt (Google) Link: https://lore.kernel.org/r/20260324123229.152424-1-tglozar@redhat.com Signed-off-by: Tomas Glozar

Documentation/rtla: Document --stack-format option

2026-03-04T14:51:56+00:00

Add documentation for --stack-format option of rtla-timerlat into its common options. Reviewed-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260119115222.744150-2-tglozar@redhat.com Signed-off-by: Tomas Glozar

Documentation/rtla: Add hwnoise to main page

2026-02-23T21:32:58+00:00

Add hwnoise to the command list and SEE ALSO section. The command list is ordered from low level to high level. Signed-off-by: Costa Shulyupin Signed-off-by: Jonathan Corbet Message-ID: <20260215131249.33437-1-costa.shul@redhat.com>

Merge tag 'trace-rtla-v7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2026-02-12T22:31:02+00:00

Pull RTLA updates from Steven Rostedt: - Remove unused function declarations Some functions were removed in recent code consolidation 6.18, but their prototypes were not removed from headers. Remove them. - Set stop threshold after enabling instances Prefer recording samples without stopping on them on the start of tracing to stopping on samples that are never recorded. This fixes flakiness of some RTLA tests and unifies behavior of sample collection between tracefs mode and BPF mode. - Consolidate usage help message implementation RTLA tools (osnoise-top, osnoise-hist, timerlat-top, timerlat-hist) each implement usage help individually. Move common logic between them into a new function to reduce code duplication. - Add BPF actions feature Add option --bpf-action to attach a BPF program (passed as filename of its ELF representation) to be executed via BPF tail call at latency threshold. - Consolidate command line option parsing Each RTLA tool implements the parsing of command line options individually. Now that we have a common structure for parameters, unify the parsing of those options common among all four tools into one function. - De-duplicate cgroup common code Two functions in utils.c, setting cgroup for comm and setting cgroup for pid, duplicate code for constructing the cgroup path. Extract it to a new helper function. - String and error handling fixes and cleanups There were several instances of unsafe string and error handling that could cause invalid memory access; fix them. Also, remove a few unused headers, update .gitignore, and deduplicate code. * tag 'trace-rtla-v7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (30 commits) rtla: Fix parse_cpu_set() bug introduced by strtoi() rtla: Fix parse_cpu_set() return value documentation rtla: Ensure null termination after read operations in utils.c rtla: Make stop_tracing variable volatile rtla: Add generated output files to gitignore rtla: Fix NULL pointer dereference in actions_parse rtla: Remove unused headers rtla: Remove redundant memset after calloc rtla: Use standard exit codes for result enum rtla: Replace atoi() with a robust strtoi() rtla: Introduce for_each_action() helper tools/rtla: Deduplicate cgroup path opening code tools/rtla: Consolidate -H/--house-keeping option parsing tools/rtla: Consolidate -P/--priority option parsing tools/rtla: Consolidate -e/--event option parsing tools/rtla: Consolidate -d/--duration option parsing tools/rtla: Consolidate -D/--debug option parsing tools/rtla: Consolidate -C/--cgroup option parsing tools/rtla: Consolidate -c/--cpus option parsing tools/rtla: Add common_parse_options() ...

Documentation: use a source-read extension for the index link boilerplate

2026-01-23T18:59:34+00:00

The root document usually has a special :ref:`genindex` link to the generated index. This is also the case for Documentation/index.rst. The other index.rst files deeper in the directory hierarchy usually don't. For SPHINXDIRS builds, the root document isn't Documentation/index.rst, but some other index.rst in the hierarchy. Currently they have a ".. only::" block to add the index link when doing SPHINXDIRS html builds. This is obviously very tedious and repetitive. The link is also added to all index.rst files in the hierarchy for SPHINXDIRS builds, not just the root document. Put the boilerplate in a sphinx-includes/subproject-index.rst file, and include it at the end of the root document for subproject builds in an ad-hoc source-read extension defined in conf.py. For now, keep having the boilerplate in translations, because this approach currently doesn't cover translated index link headers. Cc: Jonathan Corbet Cc: Mauro Carvalho Chehab Cc: Randy Dunlap Signed-off-by: Jani Nikula Tested-by: Mauro Carvalho Chehab Reviewed-by: Mauro Carvalho Chehab [jc: did s/doctree/kern_doc_dir/ ] Signed-off-by: Jonathan Corbet Message-ID: <20260123143149.2024303-1-jani.nikula@intel.com>

Documentation/rtla: Document --bpf-action option

2026-01-07T14:57:16+00:00

Add new option --bpf-action into common_timerlat_options.txt, including the format in which it takes the BPF program, and a reference to an example. Link: https://lore.kernel.org/r/20251126144205.331954-8-tglozar@redhat.com Signed-off-by: Tomas Glozar

Documentation/rtla: Rename sample/ to example/

2026-01-07T14:57:16+00:00

The sample/ directory in tools/tracing/rtla was renamed to example/ in an earlier commit. Rename it also in the documentation. Reviewed-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20251126144205.331954-7-tglozar@redhat.com Signed-off-by: Tomas Glozar

Merge tag 'trace-tools-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2025-12-05T17:34:01+00:00

Pull rtla trace tooling updates from Steven Rostedt: - Officially add Tomas Glozar as a maintainer to RTLA tool - Add for_each_monitored_cpu() helper In multiple places, RTLA tools iterate over the list of CPUs running tracer threads. Use single helper instead of repeating the for/if combination. - Remove unused variable option_index in argument parsing RTLA tools use getopt_long() for argument parsing. For its last argument, an unused variable "option_index" is passed. Remove the variable and pass NULL to getopt_long() to shorten the naturally long parsing functions, and make them more readable. - Fix unassigned nr_cpus after code consolidation In recent code consolidation, timerlat tool cleanup, previously implemented separately for each tool, was moved to a common function timerlat_free(). The cleanup relies on nr_cpus being set. This was not done in the new function, leaving the variable uninitialized. Initialize the variable properly, and remove silencing of compiler warning for uninitialized variables. - Stop tracing on user latency in BPF mode Despite the name, rtla-timerlat's -T/--thread option sets timerlat's stop_tracing_total_us option, which also stops tracing on return-from-user latency, not only on thread latency. Implement the same behavior also in BPF sample collection stop tracing handler to avoid a discrepancy and restore correspondence of behavior with the equivalent option of cyclictest. - Fix threshold actions always triggering A bug in threshold action logic caused the action to execute even if tracing did not stop because of threshold. Fix the logic to stop correctly. - Fix few minor issues in tests Extend tests that were shown to need it to 5s, fix osnoise test calling timerlat by mistake, and use new, more reliable output checking in timerlat's "top stop at failed action" test. - Do not print usage on argument parsing error RTLA prints the entire usage message on encountering errors in argument parsing, like a malformed CPU list. The usage message has gotten too long. Instead of printing it, use newly added fatal() helper function to simply exit with the error message, excluding the usage. - Fix unintuitive -C/--cgroup interface "-C cgroup" and "--cgroup cgroup" are invalid syntax, despite that being a common way to specify an option with argument. Moreover, using them fails silently and no cgroup is set. Create new helper function to unify the handling of all such options and allow all of: -Xsomething -X=something -X something as well as the equivalent for the long option. - Fix -a overriding -t argument filename Fix a bug where -a following -t custom_file.txt overrides the custom filename with the default timerlat_trace.txt. - Stop tracing correctly on multiple events at once In some race scenarios, RTLA BPF sample collection might send multiple stop tracing events via the BPF ringbuffer at once. Compare the number of events for != 0 instead of == 1 to cover for this scenario and stop tracing properly. * tag 'trace-tools-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: rtla/timerlat: Exit top main loop on any non-zero wait_retval rtla/tests: Don't rely on matching ^1ALL rtla: Fix -a overriding -t argument rtla: Fix -C/--cgroup interface tools/rtla: Replace osnoise_hist_usage("...") with fatal("...") tools/rtla: Replace osnoise_top_usage("...") with fatal("...") tools/rtla: Replace timerlat_hist_usage("...") with fatal("...") tools/rtla: Replace timerlat_top_usage("...") with fatal("...") tools/rtla: Add fatal() and replace error handling pattern rtla/tests: Fix osnoise test calling timerlat rtla/tests: Extend action tests to 5s tools/rtla: Fix --on-threshold always triggering rtla/timerlat_bpf: Stop tracing on user latency tools/rtla: Fix unassigned nr_cpus tools/rtla: Remove unused optional option_index tools/rtla: Add for_each_monitored_cpu() helper MAINTAINERS: Add Tomas Glozar as a maintainer to RTLA tool