diff options
Diffstat (limited to 'Documentation/trace/coresight')
| -rw-r--r-- | Documentation/trace/coresight/coresight-perf.rst | 31 | ||||
| -rw-r--r-- | Documentation/trace/coresight/panic.rst | 4 |
2 files changed, 33 insertions, 2 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 ----------------------------------------------------------- diff --git a/Documentation/trace/coresight/panic.rst b/Documentation/trace/coresight/panic.rst index a58aa914c241..6e4bde953cae 100644 --- a/Documentation/trace/coresight/panic.rst +++ b/Documentation/trace/coresight/panic.rst @@ -67,8 +67,8 @@ Trace data captured at the time of panic, can be read from rebooted kernel or from crashdump kernel using a special device file /dev/crash_tmc_xxx. This device file is created only when there is a valid crashdata available. -General flow of trace capture and decode incase of kernel panic -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +General flow of trace capture and decode in case of kernel panic +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1. Enable source and sink on all the cores using the sysfs interface. ETR sinks should have trace buffers allocated from reserved memory, by selecting "resrv" buffer mode from sysfs. |