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| author | Leo Yan <leo.yan@arm.com> | 2025-04-01 19:07:08 +0100 |
|---|---|---|
| committer | Suzuki K Poulose <suzuki.poulose@arm.com> | 2025-05-14 11:56:17 +0100 |
| commit | 5161890f13623175924376bc423edb63d9cb28b5 (patch) | |
| tree | a0b2d6e41ecf8a4508aa9615f68334a858f971a3 | |
| parent | 973f47a9886ac45525985790dffbf5ddeb5097a9 (diff) | |
Documentation: coresight: Document AUX pause and resume
This adds description for AUX pause and resume. It gives introduction
for what's AUX pause and resume and records usage examples.
Signed-off-by: Leo Yan <leo.yan@arm.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250401180708.385396-8-leo.yan@arm.com
| -rw-r--r-- | Documentation/trace/coresight/coresight-perf.rst | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/Documentation/trace/coresight/coresight-perf.rst b/Documentation/trace/coresight/coresight-perf.rst index d087aae7d492..30be89320621 100644 --- a/Documentation/trace/coresight/coresight-perf.rst +++ b/Documentation/trace/coresight/coresight-perf.rst @@ -78,6 +78,37 @@ enabled like:: Please refer to the kernel configuration help for more information. +Fine-grained tracing with AUX pause and resume +---------------------------------------------- + +Arm CoreSight may generate a large amount of hardware trace data, which +will lead to overhead in recording and distract users when reviewing +profiling result. To mitigate the issue of excessive trace data, Perf +provides AUX pause and resume functionality for fine-grained tracing. + +The AUX pause and resume can be triggered by associated events. These +events can be ftrace tracepoints (including static and dynamic +tracepoints) or PMU events (e.g. CPU PMU cycle event). To create a perf +session with AUX pause / resume, three configuration terms are +introduced: + +- "aux-action=start-paused": it is specified for the cs_etm PMU event to + launch in a paused state. +- "aux-action=pause": an associated event is specified with this term + to pause AUX trace. +- "aux-action=resume": an associated event is specified with this term + to resume AUX trace. + +Example for triggering AUX pause and resume with ftrace tracepoints:: + + perf record -e cs_etm/aux-action=start-paused/k,syscalls:sys_enter_openat/aux-action=resume/,syscalls:sys_exit_openat/aux-action=pause/ ls + +Example for triggering AUX pause and resume with PMU event:: + + perf record -a -e cs_etm/aux-action=start-paused/k \ + -e cycles/aux-action=pause,period=10000000/ \ + -e cycles/aux-action=resume,period=1050000/ -- sleep 1 + Perf test - Verify kernel and userspace perf CoreSight work ----------------------------------------------------------- |