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diff --git a/tools/perf/Documentation/perf-top.txt b/tools/perf/Documentation/perf-top.txt new file mode 100644 index 000000000..ee2024691 --- /dev/null +++ b/tools/perf/Documentation/perf-top.txt @@ -0,0 +1,385 @@ +perf-top(1) +=========== + +NAME +---- +perf-top - System profiling tool. + +SYNOPSIS +-------- +[verse] +'perf top' [-e <EVENT> | --event=EVENT] [<options>] + +DESCRIPTION +----------- +This command generates and displays a performance counter profile in real time. + + +OPTIONS +------- +-a:: +--all-cpus:: + System-wide collection. (default) + +-c <count>:: +--count=<count>:: + Event period to sample. + +-C <cpu-list>:: +--cpu=<cpu>:: +Monitor only on the list of CPUs provided. Multiple CPUs can be provided as a +comma-separated list with no space: 0,1. Ranges of CPUs are specified with -: 0-2. +Default is to monitor all CPUS. + +-d <seconds>:: +--delay=<seconds>:: + Number of seconds to delay between refreshes. + +-e <event>:: +--event=<event>:: + Select the PMU event. Selection can be a symbolic event name + (use 'perf list' to list all events) or a raw PMU + event (eventsel+umask) in the form of rNNN where NNN is a + hexadecimal event descriptor. + +-E <entries>:: +--entries=<entries>:: + Display this many functions. + +-f <count>:: +--count-filter=<count>:: + Only display functions with more events than this. + +--group:: + Put the counters into a counter group. + +--group-sort-idx:: + Sort the output by the event at the index n in group. If n is invalid, + sort by the first event. It can support multiple groups with different + amount of events. WARNING: This should be used on grouped events. + +-F <freq>:: +--freq=<freq>:: + Profile at this frequency. Use 'max' to use the currently maximum + allowed frequency, i.e. the value in the kernel.perf_event_max_sample_rate + sysctl. + +-i:: +--inherit:: + Child tasks do not inherit counters. + +-k <path>:: +--vmlinux=<path>:: + Path to vmlinux. Required for annotation functionality. + +--ignore-vmlinux:: + Ignore vmlinux files. + +--kallsyms=<file>:: + kallsyms pathname + +-m <pages>:: +--mmap-pages=<pages>:: + Number of mmap data pages (must be a power of two) or size + specification with appended unit character - B/K/M/G. The + size is rounded up to have nearest pages power of two value. + +-p <pid>:: +--pid=<pid>:: + Profile events on existing Process ID (comma separated list). + +-t <tid>:: +--tid=<tid>:: + Profile events on existing thread ID (comma separated list). + +-u:: +--uid=:: + Record events in threads owned by uid. Name or number. + +-r <priority>:: +--realtime=<priority>:: + Collect data with this RT SCHED_FIFO priority. + +--sym-annotate=<symbol>:: + Annotate this symbol. + +-K:: +--hide_kernel_symbols:: + Hide kernel symbols. + +-U:: +--hide_user_symbols:: + Hide user symbols. + +--demangle-kernel:: + Demangle kernel symbols. + +-D:: +--dump-symtab:: + Dump the symbol table used for profiling. + +-v:: +--verbose:: + Be more verbose (show counter open errors, etc). + +-z:: +--zero:: + Zero history across display updates. + +-s:: +--sort:: + Sort by key(s): pid, comm, dso, symbol, parent, srcline, weight, + local_weight, abort, in_tx, transaction, overhead, sample, period. + Please see description of --sort in the perf-report man page. + +--fields=:: + Specify output field - multiple keys can be specified in CSV format. + Following fields are available: + overhead, overhead_sys, overhead_us, overhead_children, sample and period. + Also it can contain any sort key(s). + + By default, every sort keys not specified in --field will be appended + automatically. + +-n:: +--show-nr-samples:: + Show a column with the number of samples. + +--show-total-period:: + Show a column with the sum of periods. + +--dsos:: + Only consider symbols in these dsos. This option will affect the + percentage of the overhead column. See --percentage for more info. + +--comms:: + Only consider symbols in these comms. This option will affect the + percentage of the overhead column. See --percentage for more info. + +--symbols:: + Only consider these symbols. This option will affect the + percentage of the overhead column. See --percentage for more info. + +-M:: +--disassembler-style=:: Set disassembler style for objdump. + +--prefix=PREFIX:: +--prefix-strip=N:: + Remove first N entries from source file path names in executables + and add PREFIX. This allows to display source code compiled on systems + with different file system layout. + +--source:: + Interleave source code with assembly code. Enabled by default, + disable with --no-source. + +--asm-raw:: + Show raw instruction encoding of assembly instructions. + +-g:: + Enables call-graph (stack chain/backtrace) recording. + +--call-graph [mode,type,min[,limit],order[,key][,branch]]:: + Setup and enable call-graph (stack chain/backtrace) recording, + implies -g. See `--call-graph` section in perf-record and + perf-report man pages for details. + +--children:: + Accumulate callchain of children to parent entry so that then can + show up in the output. The output will have a new "Children" column + and will be sorted on the data. It requires -g/--call-graph option + enabled. See the `overhead calculation' section for more details. + Enabled by default, disable with --no-children. + +--max-stack:: + Set the stack depth limit when parsing the callchain, anything + beyond the specified depth will be ignored. This is a trade-off + between information loss and faster processing especially for + workloads that can have a very long callchain stack. + + Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise. + +--ignore-callees=<regex>:: + Ignore callees of the function(s) matching the given regex. + This has the effect of collecting the callers of each such + function into one place in the call-graph tree. + +--percent-limit:: + Do not show entries which have an overhead under that percent. + (Default: 0). + +--percentage:: + Determine how to display the overhead percentage of filtered entries. + Filters can be applied by --comms, --dsos and/or --symbols options and + Zoom operations on the TUI (thread, dso, etc). + + "relative" means it's relative to filtered entries only so that the + sum of shown entries will be always 100%. "absolute" means it retains + the original value before and after the filter is applied. + +-w:: +--column-widths=<width[,width...]>:: + Force each column width to the provided list, for large terminal + readability. 0 means no limit (default behavior). + +--proc-map-timeout:: + When processing pre-existing threads /proc/XXX/mmap, it may take + a long time, because the file may be huge. A time out is needed + in such cases. + This option sets the time out limit. The default value is 500 ms. + + +-b:: +--branch-any:: + Enable taken branch stack sampling. Any type of taken branch may be sampled. + This is a shortcut for --branch-filter any. See --branch-filter for more infos. + +-j:: +--branch-filter:: + Enable taken branch stack sampling. Each sample captures a series of consecutive + taken branches. The number of branches captured with each sample depends on the + underlying hardware, the type of branches of interest, and the executed code. + It is possible to select the types of branches captured by enabling filters. + For a full list of modifiers please see the perf record manpage. + + The option requires at least one branch type among any, any_call, any_ret, ind_call, cond. + The privilege levels may be omitted, in which case, the privilege levels of the associated + event are applied to the branch filter. Both kernel (k) and hypervisor (hv) privilege + levels are subject to permissions. When sampling on multiple events, branch stack sampling + is enabled for all the sampling events. The sampled branch type is the same for all events. + The various filters must be specified as a comma separated list: --branch-filter any_ret,u,k + Note that this feature may not be available on all processors. + +--raw-trace:: + When displaying traceevent output, do not use print fmt or plugins. + +--hierarchy:: + Enable hierarchy output. + +--overwrite:: + Enable this to use just the most recent records, which helps in high core count + machines such as Knights Landing/Mill, but right now is disabled by default as + the pausing used in this technique is leading to loss of metadata events such + as PERF_RECORD_MMAP which makes 'perf top' unable to resolve samples, leading + to lots of unknown samples appearing on the UI. Enable this if you are in such + machines and profiling a workload that doesn't creates short lived threads and/or + doesn't uses many executable mmap operations. Work is being planed to solve + this situation, till then, this will remain disabled by default. + +--force:: + Don't do ownership validation. + +--num-thread-synthesize:: + The number of threads to run when synthesizing events for existing processes. + By default, the number of threads equals to the number of online CPUs. + +--namespaces:: + Record events of type PERF_RECORD_NAMESPACES and display it with the + 'cgroup_id' sort key. + +--all-cgroups:: + Record events of type PERF_RECORD_CGROUP and display it with the + 'cgroup' sort key. + +--switch-on EVENT_NAME:: + Only consider events after this event is found. + + E.g.: + + Find out where broadcast packets are handled + + perf probe -L icmp_rcv + + Insert a probe there: + + perf probe icmp_rcv:59 + + Start perf top and ask it to only consider the cycles events when a + broadcast packet arrives This will show a menu with two entries and + will start counting when a broadcast packet arrives: + + perf top -e cycles,probe:icmp_rcv --switch-on=probe:icmp_rcv + + Alternatively one can ask for --group and then two overhead columns + will appear, the first for cycles and the second for the switch-on event. + + perf top --group -e cycles,probe:icmp_rcv --switch-on=probe:icmp_rcv + + This may be interesting to measure a workload only after some initialization + phase is over, i.e. insert a perf probe at that point and use the above + examples replacing probe:icmp_rcv with the just-after-init probe. + +--switch-off EVENT_NAME:: + Stop considering events after this event is found. + +--show-on-off-events:: + Show the --switch-on/off events too. This has no effect in 'perf top' now + but probably we'll make the default not to show the switch-on/off events + on the --group mode and if there is only one event besides the off/on ones, + go straight to the histogram browser, just like 'perf top' with no events + explicitely specified does. + +--stitch-lbr:: + Show callgraph with stitched LBRs, which may have more complete + callgraph. The option must be used with --call-graph lbr recording. + Disabled by default. In common cases with call stack overflows, + it can recreate better call stacks than the default lbr call stack + output. But this approach is not full proof. There can be cases + where it creates incorrect call stacks from incorrect matches. + The known limitations include exception handing such as + setjmp/longjmp will have calls/returns not match. + +ifdef::HAVE_LIBPFM[] +--pfm-events events:: +Select a PMU event using libpfm4 syntax (see http://perfmon2.sf.net) +including support for event filters. For example '--pfm-events +inst_retired:any_p:u:c=1:i'. More than one event can be passed to the +option using the comma separator. Hardware events and generic hardware +events cannot be mixed together. The latter must be used with the -e +option. The -e option and this one can be mixed and matched. Events +can be grouped using the {} notation. +endif::HAVE_LIBPFM[] + +INTERACTIVE PROMPTING KEYS +-------------------------- + +[d]:: + Display refresh delay. + +[e]:: + Number of entries to display. + +[E]:: + Event to display when multiple counters are active. + +[f]:: + Profile display filter (>= hit count). + +[F]:: + Annotation display filter (>= % of total). + +[s]:: + Annotate symbol. + +[S]:: + Stop annotation, return to full profile display. + +[K]:: + Hide kernel symbols. + +[U]:: + Hide user symbols. + +[z]:: + Toggle event count zeroing across display updates. + +[qQ]:: + Quit. + +Pressing any unmapped key displays a menu, and prompts for input. + +include::callchain-overhead-calculation.txt[] + +SEE ALSO +-------- +linkperf:perf-stat[1], linkperf:perf-list[1], linkperf:perf-report[1] |