kernel/linux.git/tools/tracing/rtla/src/timerlat.c, branch v7.0-rc7

rtla: Remove unused headers

2026-01-07T14:57:55+00:00

Remove unused includes for and to clean up the code and reduce unnecessary dependencies. Signed-off-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260106133655.249887-12-wander@redhat.com Signed-off-by: Tomas Glozar

rtla/timerlat: Add --bpf-action option

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

Add option --bpf-action that allows the user to attach an external BPF program that will be executed via BPF tail call on latency threshold overflow. Executing additional BPF code on latency threshold overflow allows doing low-latency and in-kernel troubleshooting of the cause of the overflow. The option takes an argument, which is a path to a BPF ELF file expected to contain a function named "action_handler" in a section named "tp/timerlat_action" (the section is necessary for libbpf to assign the correct BPF program type to it). Link: https://lore.kernel.org/r/20251126144205.331954-3-tglozar@redhat.com Signed-off-by: Tomas Glozar

rtla: Set stop threshold after all instances are enabled

2026-01-07T14:57:15+00:00

This avoids startup races where one of the instances hit a threshold before all instances were enabled, and thus tracing stops without the relevant event. In particular, this is not uncommon with the tests that set a very tight threshold and then complain if there's no analysis. This also ensures that we don't stop tracing during a warmup. The downside is a small chance of having an event over the threshold early in the output, without stopping on it, which could cause user confusion. This should be less likely if the warmup feature is used, but that doesn't eliminate the race window, just the odds of an unusual spike right at that moment. Signed-off-by: Crystal Wood Link: https://lore.kernel.org/r/20251112152529.956778-6-crwood@redhat.com Signed-off-by: Tomas Glozar

tools/rtla: Fix unassigned nr_cpus

2025-11-20T12:15:54+00:00

In recently introduced timerlat_free(), the variable 'nr_cpus' is not assigned. Assign it with sysconf(_SC_NPROCESSORS_CONF) as done elsewhere. Remove the culprit: -Wno-maybe-uninitialized. The rest of the code is clean. Signed-off-by: Costa Shulyupin Reviewed-by: Tomas Glozar Fixes: 2f3172f9dd58 ("tools/rtla: Consolidate code between osnoise/timerlat and hist/top") Link: https://lore.kernel.org/r/20251002170846.437888-1-costa.shul@redhat.com Signed-off-by: Tomas Glozar

tools/rtla: Add for_each_monitored_cpu() helper

2025-11-20T12:15:53+00:00

The rtla tools have many instances of iterating over CPUs while checking if they are monitored. Add a for_each_monitored_cpu() helper macro to make the code more readable and reduce code duplication. Signed-off-by: Costa Shulyupin Reviewed-by: Tomas Glozar Link: https://lore.kernel.org/r/20251002123553.389467-1-costa.shul@redhat.com Signed-off-by: Tomas Glozar

tools/rtla: Consolidate code between osnoise/timerlat and hist/top

2025-09-27T08:52:57+00:00

Currently a lot of code is duplicated between the different rtla tools, making maintenance more difficult, and encouraging divergence such as features that are only implemented for certain tools even though they could be more broadly applicable. Merge the various main() functions into a common run_tool() with an ops struct for tool-specific details. Implement enough support for actions on osnoise to not need to keep the old params->trace_output path. Cc: John Kacur Cc: Costa Shulyupin Link: https://lore.kernel.org/20250907022325.243930-5-crwood@redhat.com Reviewed-by: Tomas Glozar Signed-off-by: Crystal Wood Signed-off-by: Steven Rostedt (Google)

tools/rtla: Create common_apply_config()

2025-09-27T08:52:46+00:00

Merge the common bits of osnoise_apply_config() and timerlat_apply_config(). Put the result in a new common.c, and move enough things to common.h so that common.c does not need to include osnoise.h. Cc: John Kacur Cc: Costa Shulyupin Link: https://lore.kernel.org/20250907022325.243930-4-crwood@redhat.com Reviewed-by: Tomas Glozar Signed-off-by: Crystal Wood Signed-off-by: Steven Rostedt (Google)

tools/rtla: Consolidate common parameters into shared structure

2025-09-27T08:51:18+00:00

timerlat_params and osnoise_params structures contain 15 identical fields. Introduce a new header common.h and define a common_params structure to consolidate shared fields, reduce code duplication, and enhance maintainability. Cc: John Kacur Link: https://lore.kernel.org/20250907022325.243930-2-crwood@redhat.com Reviewed-by: Tomas Glozar Signed-off-by: Costa Shulyupin Signed-off-by: Crystal Wood Signed-off-by: Steven Rostedt (Google)

rtla/timerlat: Introduce enum timerlat_tracing_mode

2025-07-25T20:43:56+00:00

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: Always set all tracer options

2025-03-26T14:36:39+00:00

rtla currently only sets tracer options that are explicitly set by the user, with the exception of OSNOISE_WORKLOAD. This leads to improper behavior in case rtla is run with those options not set to the default value. rtla does reset them to the original value upon exiting, but that does not protect it from starting with non-default values set either by an improperly exited rtla or by another user of the tracers. For example, after running this command: $ echo 1 > /sys/kernel/tracing/osnoise/stop_tracing_us all runs of rtla will stop at the 1us threshold, even if not requested by the user: $ rtla osnoise hist Index CPU-000 CPU-001 1 8 5 2 5 9 3 1 2 4 6 1 5 2 1 6 0 1 8 1 1 12 0 1 14 1 0 15 1 0 over: 0 0 count: 25 21 min: 1 1 avg: 3.68 3.05 max: 15 12 rtla osnoise hit stop tracing Fix the problem by setting the default value for all tracer options if the user has not provided their own value. For most of the options, it's enough to just drop the if clause checking for the value being set. For cpus, "all" is used as the default value, and for osnoise default period and runtime, default values of the osnoise_data variable in trace_osnoise.c are used. Cc: Luis Goncalves Link: https://lore.kernel.org/20250320092500.101385-5-tglozar@redhat.com Fixes: 1eceb2fc2ca5 ("rtla/osnoise: Add osnoise top mode") Fixes: 829a6c0b5698 ("rtla/osnoise: Add the hist mode") Fixes: a828cd18bc4a ("rtla: Add timerlat tool and timelart top mode") Fixes: 1eeb6328e8b3 ("rtla/timerlat: Add timerlat hist mode") Signed-off-by: Tomas Glozar Reviewed-by: John Kacur Signed-off-by: Steven Rostedt (Google)