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| -rw-r--r-- | tools/perf/Documentation/perf-ftrace.txt | 148 |
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diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt new file mode 100644 index 000000000..df4595563 --- /dev/null +++ b/tools/perf/Documentation/perf-ftrace.txt @@ -0,0 +1,148 @@ +perf-ftrace(1) +============== + +NAME +---- +perf-ftrace - simple wrapper for kernel's ftrace functionality + + +SYNOPSIS +-------- +[verse] +'perf ftrace' {trace|latency} <command> + +DESCRIPTION +----------- +The 'perf ftrace' command provides a collection of subcommands which use +kernel's ftrace infrastructure. + + 'perf ftrace trace' is a simple wrapper of the ftrace. It only supports + single thread tracing currently and just reads trace_pipe in text and then + write it to stdout. + + 'perf ftrace latency' calculates execution latency of a given function + (optionally with BPF) and display it as a histogram. + +The following options apply to perf ftrace. + +COMMON OPTIONS +-------------- + +-p:: +--pid=:: + Trace on existing process id (comma separated list). + +--tid=:: + Trace on existing thread id (comma separated list). + +-a:: +--all-cpus:: + Force system-wide collection. Scripts run without a <command> + normally use -a by default, while scripts run with a <command> + normally don't - this option allows the latter to be run in + system-wide mode. + +-C:: +--cpu=:: + Only trace for the list of CPUs provided. Multiple CPUs can + be provided as a comma separated list with no space like: 0,1. + Ranges of CPUs are specified with -: 0-2. + Default is to trace on all online CPUs. + +-v:: +--verbose:: + Increase the verbosity level. + + +OPTIONS for 'perf ftrace trace' +------------------------------- + +-t:: +--tracer=:: + Tracer to use when neither -G nor -F option is not + specified: function_graph or function. + +-F:: +--funcs:: + List available functions to trace. It accepts a pattern to + only list interested functions. + +-D:: +--delay:: + Time (ms) to wait before starting tracing after program start. + +-m:: +--buffer-size:: + Set the size of per-cpu tracing buffer, <size> is expected to + be a number with appended unit character - B/K/M/G. + +--inherit:: + Trace children processes spawned by our target. + +-T:: +--trace-funcs=:: + Select function tracer and set function filter on the given + function (or a glob pattern). Multiple functions can be given + by using this option more than once. The function argument also + can be a glob pattern. It will be passed to 'set_ftrace_filter' + in tracefs. + +-N:: +--notrace-funcs=:: + Select function tracer and do not trace functions given by the + argument. Like -T option, this can be used more than once to + specify multiple functions (or glob patterns). It will be + passed to 'set_ftrace_notrace' in tracefs. + +--func-opts:: + List of options allowed to set: + call-graph - Display kernel stack trace for function tracer. + irq-info - Display irq context info for function tracer. + +-G:: +--graph-funcs=:: + Select function_graph tracer and set graph filter on the given + function (or a glob pattern). This is useful to trace for + functions executed from the given function. This can be used more + than once to specify multiple functions. It will be passed to + 'set_graph_function' in tracefs. + +-g:: +--nograph-funcs=:: + Select function_graph tracer and set graph notrace filter on the + given function (or a glob pattern). Like -G option, this is useful + for the function_graph tracer only and disables tracing for function + executed from the given function. This can be used more than once to + specify multiple functions. It will be passed to 'set_graph_notrace' + in tracefs. + +--graph-opts:: + List of options allowed to set: + nosleep-time - Measure on-CPU time only for function_graph tracer. + noirqs - Ignore functions that happen inside interrupt. + verbose - Show process names, PIDs, timestamps, etc. + thresh=<n> - Setup trace duration threshold in microseconds. + depth=<n> - Set max depth for function graph tracer to follow. + + +OPTIONS for 'perf ftrace latency' +--------------------------------- + +-T:: +--trace-funcs=:: + Set the function name to get the histogram. Unlike perf ftrace trace, + it only allows single function to calculate the histogram. + +-b:: +--use-bpf:: + Use BPF to measure function latency instead of using the ftrace (it + uses function_graph tracer internally). + +-n:: +--use-nsec:: + Use nano-second instead of micro-second as a base unit of the histogram. + + +SEE ALSO +-------- +linkperf:perf-record[1], linkperf:perf-trace[1] |