perf-ftrace.txt (4207B)
1perf-ftrace(1) 2============== 3 4NAME 5---- 6perf-ftrace - simple wrapper for kernel's ftrace functionality 7 8 9SYNOPSIS 10-------- 11[verse] 12'perf ftrace' {trace|latency} <command> 13 14DESCRIPTION 15----------- 16The 'perf ftrace' command provides a collection of subcommands which use 17kernel's ftrace infrastructure. 18 19 'perf ftrace trace' is a simple wrapper of the ftrace. It only supports 20 single thread tracing currently and just reads trace_pipe in text and then 21 write it to stdout. 22 23 'perf ftrace latency' calculates execution latency of a given function 24 (optionally with BPF) and display it as a histogram. 25 26The following options apply to perf ftrace. 27 28COMMON OPTIONS 29-------------- 30 31-p:: 32--pid=:: 33 Trace on existing process id (comma separated list). 34 35--tid=:: 36 Trace on existing thread id (comma separated list). 37 38-a:: 39--all-cpus:: 40 Force system-wide collection. Scripts run without a <command> 41 normally use -a by default, while scripts run with a <command> 42 normally don't - this option allows the latter to be run in 43 system-wide mode. 44 45-C:: 46--cpu=:: 47 Only trace for the list of CPUs provided. Multiple CPUs can 48 be provided as a comma separated list with no space like: 0,1. 49 Ranges of CPUs are specified with -: 0-2. 50 Default is to trace on all online CPUs. 51 52-v:: 53--verbose:: 54 Increase the verbosity level. 55 56 57OPTIONS for 'perf ftrace trace' 58------------------------------- 59 60-t:: 61--tracer=:: 62 Tracer to use when neither -G nor -F option is not 63 specified: function_graph or function. 64 65-F:: 66--funcs:: 67 List available functions to trace. It accepts a pattern to 68 only list interested functions. 69 70-D:: 71--delay:: 72 Time (ms) to wait before starting tracing after program start. 73 74-m:: 75--buffer-size:: 76 Set the size of per-cpu tracing buffer, <size> is expected to 77 be a number with appended unit character - B/K/M/G. 78 79--inherit:: 80 Trace children processes spawned by our target. 81 82-T:: 83--trace-funcs=:: 84 Select function tracer and set function filter on the given 85 function (or a glob pattern). Multiple functions can be given 86 by using this option more than once. The function argument also 87 can be a glob pattern. It will be passed to 'set_ftrace_filter' 88 in tracefs. 89 90-N:: 91--notrace-funcs=:: 92 Select function tracer and do not trace functions given by the 93 argument. Like -T option, this can be used more than once to 94 specify multiple functions (or glob patterns). It will be 95 passed to 'set_ftrace_notrace' in tracefs. 96 97--func-opts:: 98 List of options allowed to set: 99 call-graph - Display kernel stack trace for function tracer. 100 irq-info - Display irq context info for function tracer. 101 102-G:: 103--graph-funcs=:: 104 Select function_graph tracer and set graph filter on the given 105 function (or a glob pattern). This is useful to trace for 106 functions executed from the given function. This can be used more 107 than once to specify multiple functions. It will be passed to 108 'set_graph_function' in tracefs. 109 110-g:: 111--nograph-funcs=:: 112 Select function_graph tracer and set graph notrace filter on the 113 given function (or a glob pattern). Like -G option, this is useful 114 for the function_graph tracer only and disables tracing for function 115 executed from the given function. This can be used more than once to 116 specify multiple functions. It will be passed to 'set_graph_notrace' 117 in tracefs. 118 119--graph-opts:: 120 List of options allowed to set: 121 nosleep-time - Measure on-CPU time only for function_graph tracer. 122 noirqs - Ignore functions that happen inside interrupt. 123 verbose - Show process names, PIDs, timestamps, etc. 124 thresh=<n> - Setup trace duration threshold in microseconds. 125 depth=<n> - Set max depth for function graph tracer to follow. 126 127 128OPTIONS for 'perf ftrace latency' 129--------------------------------- 130 131-T:: 132--trace-funcs=:: 133 Set the function name to get the histogram. Unlike perf ftrace trace, 134 it only allows single function to calculate the histogram. 135 136-b:: 137--use-bpf:: 138 Use BPF to measure function latency instead of using the ftrace (it 139 uses function_graph tracer internally). 140 141-n:: 142--use-nsec:: 143 Use nano-second instead of micro-second as a base unit of the histogram. 144 145 146SEE ALSO 147-------- 148linkperf:perf-record[1], linkperf:perf-trace[1]