kernel/linux.git/tools/tracing/rtla/src/timerlat.bpf.c, branch v6.19.12

rtla/timerlat_bpf: Stop tracing on user latency

2025-11-20T12:15:55+00:00

rtla-timerlat allows a *thread* latency threshold to be set via the -T/--thread option. However, the timerlat tracer calls this *total* latency (stop_tracing_total_us), and stops tracing also when the return-to-user latency is over the threshold. Change the behavior of the timerlat BPF program to reflect what the timerlat tracer is doing, to avoid discrepancy between stopping collecting data in the BPF program and stopping tracing in the timerlat tracer. Cc: stable@vger.kernel.org Fixes: e34293ddcebd ("rtla/timerlat: Add BPF skeleton to collect samples") Reviewed-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20251006143100.137255-1-tglozar@redhat.com Signed-off-by: Tomas Glozar

rtla/timerlat_bpf: Allow resuming tracing

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

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 BPF skeleton to collect samples

2025-03-04T17:35:18+00:00

Add BPF program that attaches to the osnoise:timerlat_sample tracepoint and collects both the summary and the histogram (if requested) into BPF maps (one map of each kind per context). The program is designed to be used for both timerlat-top and timerlat-hist. If using with timerlat-top, the "entries" parameter is set to zero, which prevents the BPF program from recording histogram entries. In that case, the maps for histograms do not have to be created, as the BPF verifier will identify the code using them as unreachable. An IRQ or thread latency threshold might be supplied to stop recording if hit, similar to the timerlat tracer threshold, which stops ftrace tracing if hit. A BPF ringbuffer is used to signal threshold overflow to userspace. In aa-only mode, this is the only function of the BPF program. Cc: John Kacur Cc: Luis Goncalves Cc: Gabriele Monaco Cc: Clark Williams Link: https://lore.kernel.org/20250218145859.27762-5-tglozar@redhat.com Signed-off-by: Tomas Glozar Signed-off-by: Steven Rostedt (Google)