kernel/linux.git/tools/tracing/rtla/src/timerlat_top.c, branch v7.1.12

rtla/timerlat_top: Fix on-threshold actions firing on signal

2026-08-09T18:26:24+00:00

[ Upstream commit fafb66e5903c2bcfc7b7e259042a8282f18a6faa ] A bug was reported when rtla-timerlat-top tool performs on-threshold actions, even though no threshold was hit. This is reproduced even if no threshold is set at all: $ rtla timerlat top -q -c 0 --on-threshold shell,command='echo BAD' BAD Timer Latency ... The bug is due to incorrect logic in timerlat_top_bpf_main_loop(). The loop uses timerlat_bpf_wait(), the return values of which are: - > 0 (number of ringbuffer entries): at least 1 CPU hit threshold - = 0: time out - < 0: wait was interrupted by a signal Commit 3138df6f0cd0 ("rtla/timerlat: Exit top main loop on any non-zero wait_retval") changed the condition for "threshold hit" from "wait_reval == 1" (exactly 1 CPU hit threshold) to "wait_retval != 0", to fix a race where multiple CPUs hit the threshold at the same time. That also made it incorrectly include a signal (< 0), coming from either duration expired (SIGALRM) or user interrupt (SIGINT). Check for wait_retval greater than zero in the if condition to cover all return values correctly. Fixes: 3138df6f0cd0 ("rtla/timerlat: Exit top main loop on any non-zero wait_retval") Reported-by: Attila Fazekas Reviewed-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260713141047.687877-1-tglozar@redhat.com Signed-off-by: Tomas Glozar Signed-off-by: Sasha Levin

tools/rtla: Fix --dump-tasks usage in timerlat

2026-07-24T14:19:14+00:00

[ Upstream commit 704fe8f3d97bba842f5f357e317116f1b88169e8 ] Fix --dump-task to --dump-tasks in timerlat_hist usage string and getopt_long table for consistency with timerlat_top. Add missing --dump-tasks to timerlat_top usage synopsis. Assisted-by: Claude:claude-opus-4-6 Signed-off-by: Costa Shulyupin Fixes: 2091336b9a8b ("rtla/timerlat_hist: Add auto-analysis support") Link: https://lore.kernel.org/r/20260414185223.65353-1-costa.shul@redhat.com Signed-off-by: Tomas Glozar Signed-off-by: Sasha Levin

rtla: Fix parsing of multi-character short options

2026-06-04T08:53:25+00:00

A bug was reported where the parsing of multi-character short options, be it a short option with an argument specified without space (e.g. "-p100") or multiple short options in one argument (e.g. -un), ignores options specific to individual tools. Furthermore, if the rest of the option is supposed to be an argument, it gets reinterpreted as a string of options. For example, -p100 gets interpreted as -100, which is due to hackish implementation read as --no-thread --no-irq --no-irq with timerlat hist, causing rtla to error out: $ rtla timerlat hist -p100 no-irq and no-thread set, there is nothing to do here This behavior is caused by getopt_long() being called twice on each argument, once in common_parse_options(), once in [tool]_parse_args(): - common_parse_options() calls getopt_long() with an array of options common for all rtla tools, while suppressing errors (opterr = 0). - If the option fails to parse, common_parse_options() returns 0. - If 0 is returned from common_parse_options(), [tool]_parse_args() calls getopt_long() again, with its own set of options. * [tool] means one of {osnoise,timerlat}_{top,hist} At least in glibc, getopt_long() increments its internal nextchar variable even if the option is not recognized. That means that in the case of "-p100", common_parse_options() sets nextchar pointing to '1', and timerlat_hist_parse_args() sees '1', not 'p'; the same then repeats for the first and second '0'. As there is no way to restore the correct internal state of getopt_long() reliably, fix the issue by merging the common options back to the longopt array and option string of the [tool]_parse_args() functions using a macro; only the switch part is left in the original function, which is renamed to set_common_option(). Fixes: 850cd24cb6d6 ("tools/rtla: Add common_parse_options()") Reported-by: John Kacur Tested-by: John Kacur Link: https://lore.kernel.org/r/20260602125506.3325345-1-tglozar@redhat.com Signed-off-by: Tomas Glozar

rtla: Introduce common_threshold_handler() helper

2026-03-10T09:32:37+00:00

Several functions duplicate the logic for handling threshold actions. When a threshold is reached, these functions stop the trace, perform configured actions, and restart the trace if --on-threshold continue is set. Create common_threshold_handler() to centralize this shared logic and avoid code duplication. The function executes the configured threshold actions and restarts the necessary trace instances when appropriate. Also add should_continue_tracing() helper to encapsulate the check for whether tracing should continue after a threshold event, improving code readability at call sites. In timerlat_top_bpf_main_loop(), use common_params directly instead of casting through timerlat_params when only common fields are needed. Signed-off-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260309195040.1019085-5-wander@redhat.com Signed-off-by: Tomas Glozar

rtla: Exit on memory allocation failures during initialization

2026-03-10T09:32:37+00:00

Most memory allocations in rtla happen during early initialization before any resources are acquired that would require cleanup. In these cases, propagating allocation errors just adds complexity without any benefit. There's nothing to clean up, and the program must exit anyway. This patch introduces fatal allocation wrappers (calloc_fatal, reallocarray_fatal, strdup_fatal) that call fatal() on allocation failure. These wrappers simplify the code by eliminating unnecessary error propagation paths. The patch converts early allocations to use these wrappers in actions_init() and related action functions, osnoise_context_alloc() and osnoise_init_tool(), trace_instance_init() and trace event functions, and parameter structure allocations in main functions. This simplifies the code while maintaining the same behavior: immediate exit on allocation failure during initialization. Allocations that require cleanup, such as those in histogram allocation functions with goto cleanup paths, are left unchanged and continue to return errors. Signed-off-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260309195040.1019085-2-wander@redhat.com Signed-off-by: Tomas Glozar

tools/rtla: Remove unneeded nr_cpus from for_each_monitored_cpu

2026-03-09T07:49:17+00:00

nr_cpus does not change at runtime, so passing it through the macro argument is unnecessary. Remove the argument and use the global nr_cpus instead. Signed-off-by: Costa Shulyupin Link: https://lore.kernel.org/r/20260306194953.2511960-5-costa.shul@redhat.com Signed-off-by: Tomas Glozar

tools/rtla: Remove unneeded nr_cpus members

2026-03-09T07:49:17+00:00

nr_cpus does not change at runtime, so keeping it in struct members is unnecessary. Use the global nr_cpus instead of struct members. Signed-off-by: Costa Shulyupin Link: https://lore.kernel.org/r/20260306194953.2511960-4-costa.shul@redhat.com Signed-off-by: Tomas Glozar

tools/rtla: Remove unneeded nr_cpus arguments

2026-03-09T07:49:17+00:00

nr_cpus does not change at runtime, so passing it through function arguments is unnecessary. Use the global nr_cpus instead of propagating it via parameters. Signed-off-by: Costa Shulyupin Link: https://lore.kernel.org/r/20260306194953.2511960-3-costa.shul@redhat.com Signed-off-by: Tomas Glozar

tools/rtla: Consolidate nr_cpus usage across all tools

2026-03-09T07:49:16+00:00

sysconf(_SC_NPROCESSORS_CONF) (via get_nprocs_conf) reflects cpu_possible_mask, which is fixed at boot time, so querying it repeatedly is unnecessary. Replace multiple calls to sysconf(_SC_NPROCESSORS_CONF) with a single global nr_cpus variable initialized once at startup. `#pragma once` in timerlat_u.h is needed for pre-C23 compilers to avoid redefinition errors. Signed-off-by: Costa Shulyupin Link: https://lore.kernel.org/r/20260306194953.2511960-2-costa.shul@redhat.com Signed-off-by: Tomas Glozar

rtla/timerlat: Add --stack-format option

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

In the current implementation, the auto-analysis code for printing the stack captured in the tracefs buffer of the aa instance stops at the first encountered address that cannot be resolved into a function symbol. This is not always the desired behavior on all platforms; sometimes, there might be resolvable entries after unresolvable ones, and sometimes, the user might want to inspect the raw pointers for the unresolvable entries. Add a new option, --stack-format, with three values: - truncate: stop at first unresolvable entry. This is the current behavior, and is kept as the default. - skip: skip unresolvable entries, but do not stop on them. - full: print all entries, including unresolvable ones. To make this work, the "size" field of the stack entry is now also read and used as the maximum number of entries to print, capped at 64, since that is the fixed length of the "caller" field. Link: https://lore.kernel.org/r/20260119115222.744150-1-tglozar@redhat.com Signed-off-by: Tomas Glozar