This series adds a feature that allows to user to specify certain kinds of "actions" to be executed at one of two places in the rtla measurement: when tracing is stopped on latency threshold, and at the end of tracing.
Two new options are added: -A/--on-threshold, and -N/--on-end, taking the action as an argument. For example: $ rtla timerlat hist -T 10 -A shell,command="echo Threshold" \ -N shell,command="echo Tracing stopped" will print "Threshold" if a thread latency higher than 10 microseconds is reached, and "Tracing stopped" always at the end. The list of possible actions is extensible and is covered in the commit messages. Later, a documentation patch series will be sent with clear explanation of every action and its syntax. Notably, a special action "continue" resumes tracing. For example: $ rtla timerlat hist -T 100 -A shell,command="echo Threshold" \ -A continue -d 10s will print "Threshold" as many times as tracing is stopped after thread latency reaches 100us. The feature was inspired by a case where collecting perf data on rtla latency overflow was required, which can be done by sending a signal to the perf process. Example of this with Intel PT aux buffer: $ perf record --cpu 0 -e intel_pt// -S -- rtla timerlat top -q -T 100 \ -c 0 -A signal,pid=parent,num=12 -A continue In general, the feature is aiming to allow integration with external tooling. To implement even more flexibility, passing context to the shell through environmental variables, or even an entire scripting language with access to the rtla internals can be implemented if needed. Tomas Glozar (8): rtla/timerlat: Introduce enum timerlat_tracing_mode rtla/timerlat: Add action on threshold feature rtla/timerlat_bpf: Allow resuming tracing rtla/timerlat: Add continue action rtla/timerlat: Add action on end feature rtla/tests: Check rtla output with grep rtla/tests: Add tests for actions rtla/tests: Limit duration to maximum of 10s tools/tracing/rtla/src/Build | 1 + tools/tracing/rtla/src/actions.c | 260 +++++++++++++++++++++++++ tools/tracing/rtla/src/actions.h | 52 +++++ tools/tracing/rtla/src/timerlat.bpf.c | 13 +- tools/tracing/rtla/src/timerlat.c | 24 ++- tools/tracing/rtla/src/timerlat.h | 24 ++- tools/tracing/rtla/src/timerlat_bpf.c | 13 ++ tools/tracing/rtla/src/timerlat_bpf.h | 3 + tools/tracing/rtla/src/timerlat_hist.c | 145 ++++++++++---- tools/tracing/rtla/src/timerlat_top.c | 167 ++++++++++------ tools/tracing/rtla/tests/engine.sh | 21 +- tools/tracing/rtla/tests/hwnoise.t | 8 +- tools/tracing/rtla/tests/osnoise.t | 4 +- tools/tracing/rtla/tests/timerlat.t | 36 +++- 14 files changed, 652 insertions(+), 119 deletions(-) create mode 100644 tools/tracing/rtla/src/actions.c create mode 100644 tools/tracing/rtla/src/actions.h -- 2.49.0
