kernel/linux.git/Documentation/tools/rtla, branch v6.19.11

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

rtla: Fix -C/--cgroup interface

2025-11-21T09:30:27+00:00

Currently, user can only specify cgroup to the tracer's thread the following ways: `-C[cgroup]` `-C[=cgroup]` `--cgroup[=cgroup]` If user tries to specify cgroup as `-C [cgroup]` or `--cgroup [cgroup]`, the parser silently fails and rtla's cgroup is used for the tracer threads. To make interface more user-friendly, allow user to specify cgroup in the aforementioned way, i.e. `-C [cgroup]` and `--cgroup [cgroup]`. Refactor identical logic between -t/--trace and -C/--cgroup into a common function. Change documentation to reflect this user interface change. Fixes: a957cbc02531 ("rtla: Add -C cgroup support") Signed-off-by: Ivan Pravdin Reviewed-by: Tomas Glozar Link: https://lore.kernel.org/r/16132f1565cf5142b5fbd179975be370b529ced7.1762186418.git.ipravdin.official@gmail.com [ use capital letter in subject, as required by tracing subsystem ] Signed-off-by: Tomas Glozar

Documentation/rtla: Include defaults for tracer options

2025-11-05T18:19:24+00:00

Commit 0122938a7ab4 ("rtla: Always set all tracer options") changed the behavior of RTLA to always set all osnoise and timerlat tracer options to default values taken from the tracers whenever an RTLA measurement is started. The change was done to make RTLA results consistent on subsequent runs of the same command. Include the default values for tracer options also in documentation where appropriate. Signed-off-by: Tomas Glozar Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20251010083338.478961-10-tglozar@redhat.com>

Documentation/rtla: Mention default cgroup state

2025-11-05T18:19:17+00:00

The RTLA option -C/--cgroup is used to set a cgroup for workload threads. This is either a specific cgroup, if passed an argument, or rtla's cgroup, if no argument is given. Expand the documentation of the -C option to also include the information about the cgroup settings when the option is not specified. Signed-off-by: Tomas Glozar Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20251010083338.478961-8-tglozar@redhat.com>

Documentation/rtla: Mention default priority

2025-11-05T18:19:13+00:00

RTLA allows the priority of workload threads to be set using the -P option. This is covered in docs, but the default state for RTLA's own user workload (implemented in timerlat_u.c) is not mentioned. Add mention of the default user workload priority as well as a reference to osnoise and timerlat tracers for kernel workload priority. Signed-off-by: Tomas Glozar Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20251010083338.478961-7-tglozar@redhat.com>

Documentation/rtla: Correct tracer name for common options

2025-11-05T18:19:09+00:00

Several options in common_options.rst say "osnoise tracer" for both osnoise and timerlat. Use |tool| variable so that the correct tool name is used. Fixes: b1be48307de4 ("rtla: Add rtla osnoise top documentation") Signed-off-by: Tomas Glozar Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20251010083338.478961-6-tglozar@redhat.com>

Documentation/rtla: Fix typo in common_timerlat_options.txt

2025-11-05T18:19:06+00:00

Fix spelling error "equilavent" in place of "equivalent". Fixes: 173a3b014827 ("rtla/timerlat: Add the automatic trace option") Signed-off-by: Tomas Glozar Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20251010083338.478961-5-tglozar@redhat.com>

Documentation/rtla: Fix typo in rtla-timerlat-top.rst

2025-11-05T18:19:03+00:00

Fix "seem" in place of intended "seen" in rtla-timerlat-top documentation. Fixes: df337d014b57 ("rtla: Add rtla timerlat top documentation") Signed-off-by: Tomas Glozar Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20251010083338.478961-4-tglozar@redhat.com>

Documentation/rtla: Fix typo in common_timerlat_options.txt

2025-11-05T18:18:59+00:00

Fix "awakes" being used in place of "awakened" in --users-threads option documentation. Fixes: 612738321774 ("Documentation: Add tools/rtla timerlat -u option documentation") Signed-off-by: Tomas Glozar Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20251010083338.478961-3-tglozar@redhat.com>

Documentation/rtla: Fix typo in common_options.txt

2025-11-05T18:18:50+00:00

Fix "unlike" being spelled "nlike" in --on-threshold documentation. Fixes: 70165c78e31d ("Documentation/rtla: Add actions feature") Signed-off-by: Tomas Glozar Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20251010083338.478961-2-tglozar@redhat.com>