linux/tools/tracing/rtla/src, branch v6.17

rtla/actions: Fix condition for buffer reallocation

2025-09-27T10:01:20Z

The condition to check if the actions buffer needs to be resized was incorrect. The check `self->size >= self->len` would evaluate to true on almost every call to `actions_new()`, causing the buffer to be reallocated unnecessarily each time an action was added. Fix the condition to `self->len >= self.size`, ensuring that the buffer is only resized when it is actually full. Cc: John Kacur Cc: Luis Goncalves Cc: Arnaldo Carvalho de Melo Cc: Chang Yin Cc: Costa Shulyupin Cc: Crystal Wood Cc: Gabriele Monaco Link: https://lore.kernel.org/20250915181101.52513-1-wander@redhat.com Fixes: 6ea082b171e00 ("rtla/timerlat: Add action on threshold feature") Signed-off-by: Wander Lairson Costa Reviewed-by: Tomas Glozar Signed-off-by: Steven Rostedt (Google)

rtla: Fix buffer overflow in actions_parse

2025-09-27T09:57:29Z

Currently, tests 3 and 13-22 in tests/timerlat.t fail with error: *** buffer overflow detected ***: terminated timeout: the monitored command dumped core The result of running `sudo make check` is tests/timerlat.t (Wstat: 0 Tests: 22 Failed: 11) Failed tests: 3, 13-22 Files=3, Tests=34, 140 wallclock secs ( 0.07 usr 0.01 sys + 27.63 cusr 27.96 csys = 55.67 CPU) Result: FAIL Fix buffer overflow in actions_parse to avoid this error. After this change, the tests results are tests/hwnoise.t ... ok tests/osnoise.t ... ok tests/timerlat.t .. ok All tests successful. Files=3, Tests=34, 186 wallclock secs ( 0.06 usr 0.01 sys + 41.10 cusr 44.38 csys = 85.55 CPU) Result: PASS Link: https://lore.kernel.org/164ffc2ec8edacaf1295789dad82a07817b6263d.1757034919.git.ipravdin.official@gmail.com Fixes: 6ea082b171e0 ("rtla/timerlat: Add action on threshold feature") Signed-off-by: Ivan Pravdin Reviewed-by: Tomas Glozar Signed-off-by: Steven Rostedt (Google)

rtla/timerlat: Add action on end feature

2025-07-25T20:43:57Z

Implement actions on end next to actions on threshold. A new option, --on-end is added, parallel to --on-threshold. Instead of being executed whenever a latency threshold is reached, it is executed at the end of the measurement. For example: $ rtla timerlat hist -d 5s --on-end trace will save the trace output at the end. All actions supported by --on-threshold are also supported by --on-end, except for continue, which does nothing with --on-end. Cc: John Kacur Cc: Luis Goncalves Cc: Arnaldo Carvalho de Melo Cc: Chang Yin Cc: Costa Shulyupin Cc: Crystal Wood Cc: Gabriele Monaco Link: https://lore.kernel.org/20250626123405.1496931-6-tglozar@redhat.com Signed-off-by: Tomas Glozar Signed-off-by: Steven Rostedt (Google)

rtla/timerlat: Add continue action

2025-07-25T20:43:57Z

Introduce option to resume tracing after a latency threshold overflow. The option is implemented as an action named "continue". Example: $ rtla timerlat top -q -T 200 -d 1s --on-threshold \ exec,command="echo Threshold" --on-threshold continue Threshold Threshold Threshold Timer Latency ... The feature is supported for both hist and top. After the continue action is executed, processing of the list of actions is stopped and tracing is resumed. Cc: John Kacur Cc: Luis Goncalves Cc: Arnaldo Carvalho de Melo Cc: Chang Yin Cc: Costa Shulyupin Cc: Crystal Wood Cc: Gabriele Monaco Link: https://lore.kernel.org/20250626123405.1496931-5-tglozar@redhat.com Signed-off-by: Tomas Glozar Signed-off-by: Steven Rostedt (Google)

rtla/timerlat_bpf: Allow resuming tracing

2025-07-25T20:43:56Z

Currently, rtla-timerlat BPF program uses a global variable stored in a .bss section to store whether tracing has been stopped. Move the information to a separate map, so that it is easily writable from userspace, and add a function that clears the value, resuming tracing after it has been stopped. Cc: John Kacur Cc: Luis Goncalves Cc: Arnaldo Carvalho de Melo Cc: Chang Yin Cc: Costa Shulyupin Cc: Crystal Wood Cc: Gabriele Monaco Link: https://lore.kernel.org/20250626123405.1496931-4-tglozar@redhat.com Signed-off-by: Tomas Glozar Signed-off-by: Steven Rostedt (Google)

rtla/timerlat: Add action on threshold feature

2025-07-25T20:43:56Z

Extend the functionality provided by the -t/--trace option, which triggers saving the contents of a tracefs buffer after tracing is stopped, to support implementing arbitrary actions. A new option, --on-threshold, is added, taking an argument that further specifies the action. Actions added in this patch are: - trace[,file=]: Saves tracefs buffer, optionally taking a filename. - signal,num=,pid=: Sends signal to process. "parent" might be specified instead of number to send signal to parent process. - shell,command=: Execute shell command. Multiple actions may be specified and will be executed in order, including multiple actions of the same type. Trace output requested via -t and -a now adds a trace action to the end of the list. If an action fails, the following actions are not executed. For example, this command: $ rtla timerlat -T 20 --on-threshold trace \ --on-threshold shell,command="grep ipi_send timerlat_trace.txt" \ --on-threshold signal,num=2,pid=parent will send signal 2 (SIGINT) to parent process, but only if saved trace contains the text "ipi_send". This way, the feature can be used for flexible reactions on latency spikes, and allows combining rtla with other tooling like perf. Cc: John Kacur Cc: Luis Goncalves Cc: Arnaldo Carvalho de Melo Cc: Chang Yin Cc: Costa Shulyupin Cc: Crystal Wood Cc: Gabriele Monaco Link: https://lore.kernel.org/20250626123405.1496931-3-tglozar@redhat.com Signed-off-by: Tomas Glozar Signed-off-by: Steven Rostedt (Google)

rtla/timerlat: Introduce enum timerlat_tracing_mode

2025-07-25T20:43:56Z

After the introduction of BPF-based sample collection, rtla-timerlat effectively runs in one of three modes: - Pure BPF mode, with tracefs only being used to set up the timerlat tracer. Sample processing and stop on threshold are handled by BPF. - tracefs mode. BPF is unsupported or kernel is lacking the necessary trace event (osnoise:timerlat_sample). Stop on theshold is handled by timerlat tracer stopping tracing in all instances. - BPF/tracefs mixed mode - BPF is used for sample collection for top or histogram, tracefs is used for trace output and/or auto-analysis. Stop on threshold is handled both through BPF program, which stops sample collection for top/histogram and wakes up rtla, and by timerlat tracer, which stops tracing for trace output/auto-analysis instances. Add enum timerlat_tracing_mode, with three values: - TRACING_MODE_BPF - TRACING_MODE_TRACEFS - TRACING_MODE_MIXED Those represent the modes described above. A field of this type is added to struct timerlat_params, named "mode", replacing the no_bpf variable. params->mode is set in timerlat_{top,hist}_parse_args to TRACING_MODE_BPF or TRACING_MODE_MIXED based on whether trace output and/or auto-analysis is requested. timerlat_{top,hist}_main then checks if BPF is not unavailable or disabled, in that case, it sets params->mode to TRACING_MODE_TRACEFS. A condition is added to timerlat_apply_config that skips setting timerlat tracer thresholds if params->mode is TRACING_MODE_BPF (those are unnecessary, since they only turn off tracing, which is already turned off in that case, since BPF is used to collect samples). Cc: John Kacur Cc: Luis Goncalves Cc: Arnaldo Carvalho de Melo Cc: Chang Yin Cc: Costa Shulyupin Cc: Crystal Wood Cc: Gabriele Monaco Link: https://lore.kernel.org/20250626123405.1496931-2-tglozar@redhat.com Signed-off-by: Tomas Glozar Signed-off-by: Steven Rostedt (Google)

rtla: Define _GNU_SOURCE in timerlat_bpf.c

2025-05-07T21:25:46Z

Newer versions of glibc include a definition of struct sched_attr in bits/sched.h (included through sched.h which is included by rtla). Commit 0eecee340672 ("tools/rtla: fix collision with glibc sched_attr/sched_set_attr") has modified the definition of struct sched_attr in utils.h, so that it is only applied with older versions of glibc that do not define it, in order to prevent build failure. The definition in bits/sched.h depends on _GNU_SOURCE. timerlat_bpf.c does not define _GNU_SOURCE, making it fall back to the definition in utils.h. The latter has two fields less, leading to shifted offsets of struct timerlat_params in timerlat_bpf_init. Because of the shift, timerlat_bpf_init incorrectly reads params->entries as 0 for timerlat-hist and disables the creation of histogram maps, causing breakage in BPF sample collection mode: $ rtla timerlat hist -d 1s Error pulling BPF data Fix the issue by also defining _GNU_SOURCE in timerlat_bpf.c. Cc: John Kacur Cc: Luis Goncalves Link: https://lore.kernel.org/20250430144651.621766-1-tglozar@redhat.com Fixes: e34293ddcebd ("rtla/timerlat: Add BPF skeleton to collect samples") Signed-off-by: Tomas Glozar Signed-off-by: Steven Rostedt (Google)

rtla: Define __NR_sched_setattr for LoongArch

2025-05-07T20:35:31Z

When executing "make -C tools/tracing/rtla" on LoongArch, there exists the following error: src/utils.c:237:24: error: '__NR_sched_setattr' undeclared Just define __NR_sched_setattr for LoongArch if not exist. Link: https://lore.kernel.org/20250422074917.25771-1-yangtiezhu@loongson.cn Reported-by: Haiyong Sun Signed-off-by: Tiezhu Yang Signed-off-by: Steven Rostedt (Google)

rtla: Set distinctive exit value for failed tests

2025-05-07T19:36:19Z

A test is considered failed when a sample trace exceeds the threshold. Failed tests return the same exit code as passed tests, requiring test frameworks to determine the result by searching for "hit stop tracing" in the output. Assign a distinct exit code for failed tests to enable the use of shell expressions and seamless integration with testing frameworks without the need to parse output. Add enum type for return value. Update `make check`. Cc: Daniel Bristot de Oliveira Cc: John Kacur Cc: "Luis Claudio R. Goncalves" Cc: Eder Zulian Cc: Dan Carpenter Cc: Jan Stancek Link: https://lore.kernel.org/20250417185757.2194541-1-costa.shul@redhat.com Signed-off-by: Costa Shulyupin Reviewed-by: Tomas Glozar Signed-off-by: Steven Rostedt (Google)