diff options
Diffstat (limited to 'tools/perf/Documentation/perf-trace.txt')
| -rw-r--r-- | tools/perf/Documentation/perf-trace.txt | 347 |
1 files changed, 347 insertions, 0 deletions
diff --git a/tools/perf/Documentation/perf-trace.txt b/tools/perf/Documentation/perf-trace.txt new file mode 100644 index 000000000..f0da8cf63 --- /dev/null +++ b/tools/perf/Documentation/perf-trace.txt @@ -0,0 +1,347 @@ +perf-trace(1) +============= + +NAME +---- +perf-trace - strace inspired tool + +SYNOPSIS +-------- +[verse] +'perf trace' +'perf trace record' + +DESCRIPTION +----------- +This command will show the events associated with the target, initially +syscalls, but other system events like pagefaults, task lifetime events, +scheduling events, etc. + +This is a live mode tool in addition to working with perf.data files like +the other perf tools. Files can be generated using the 'perf record' command +but the session needs to include the raw_syscalls events (-e 'raw_syscalls:*'). +Alternatively, 'perf trace record' can be used as a shortcut to +automatically include the raw_syscalls events when writing events to a file. + +The following options apply to perf trace; options to perf trace record are +found in the perf record man page. + +OPTIONS +------- + +-a:: +--all-cpus:: + System-wide collection from all CPUs. + +-e:: +--expr:: +--event:: + List of syscalls and other perf events (tracepoints, HW cache events, + etc) to show. Globbing is supported, e.g.: "epoll_*", "*msg*", etc. + See 'perf list' for a complete list of events. + Prefixing with ! shows all syscalls but the ones specified. You may + need to escape it. + +--filter=<filter>:: + Event filter. This option should follow an event selector (-e) which + selects tracepoint event(s). + + +-D msecs:: +--delay msecs:: +After starting the program, wait msecs before measuring. This is useful to +filter out the startup phase of the program, which is often very different. + +-o:: +--output=:: + Output file name. + +-p:: +--pid=:: + Record events on existing process ID (comma separated list). + +-t:: +--tid=:: + Record events on existing thread ID (comma separated list). + +-u:: +--uid=:: + Record events in threads owned by uid. Name or number. + +-G:: +--cgroup:: + Record events in threads in a cgroup. + + Look for cgroups to set at the /sys/fs/cgroup/perf_event directory, then + remove the /sys/fs/cgroup/perf_event/ part and try: + + perf trace -G A -e sched:*switch + + Will set all raw_syscalls:sys_{enter,exit}, pgfault, vfs_getname, etc + _and_ sched:sched_switch to the 'A' cgroup, while: + + perf trace -e sched:*switch -G A + + will only set the sched:sched_switch event to the 'A' cgroup, all the + other events (raw_syscalls:sys_{enter,exit}, etc are left "without" + a cgroup (on the root cgroup, sys wide, etc). + + Multiple cgroups: + + perf trace -G A -e sched:*switch -G B + + the syscall ones go to the 'A' cgroup, the sched:sched_switch goes + to the 'B' cgroup. + +--filter-pids=:: + Filter out events for these pids and for 'trace' itself (comma separated list). + +-v:: +--verbose:: + Increase the verbosity level. + +--no-inherit:: + Child tasks do not inherit counters. + +-m:: +--mmap-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. + +-C:: +--cpu:: +Collect samples 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. +In per-thread mode with inheritance mode on (default), Events are captured only when +the thread executes on the designated CPUs. Default is to monitor all CPUs. + +--duration:: + Show only events that had a duration greater than N.M ms. + +--sched:: + Accrue thread runtime and provide a summary at the end of the session. + +--failure:: + Show only syscalls that failed, i.e. that returned < 0. + +-i:: +--input:: + Process events from a given perf data file. + +-T:: +--time:: + Print full timestamp rather time relative to first sample. + +--comm:: + Show process COMM right beside its ID, on by default, disable with --no-comm. + +-s:: +--summary:: + Show only a summary of syscalls by thread with min, max, and average times + (in msec) and relative stddev. + +-S:: +--with-summary:: + Show all syscalls followed by a summary by thread with min, max, and + average times (in msec) and relative stddev. + +--errno-summary:: + To be used with -s or -S, to show stats for the errnos experienced by + syscalls, using only this option will trigger --summary. + +--tool_stats:: + Show tool stats such as number of times fd->pathname was discovered thru + hooking the open syscall return + vfs_getname or via reading /proc/pid/fd, etc. + +-f:: +--force:: + Don't complain, do it. + +-F=[all|min|maj]:: +--pf=[all|min|maj]:: + Trace pagefaults. Optionally, you can specify whether you want minor, + major or all pagefaults. Default value is maj. + +--syscalls:: + Trace system calls. This options is enabled by default, disable with + --no-syscalls. + +--call-graph [mode,type,min[,limit],order[,key][,branch]]:: + Setup and enable call-graph (stack chain/backtrace) recording. + See `--call-graph` section in perf-record and perf-report + man pages for details. The ones that are most useful in 'perf trace' + are 'dwarf' and 'lbr', where available, try: 'perf trace --call-graph dwarf'. + + Using this will, for the root user, bump the value of --mmap-pages to 4 + times the maximum for non-root users, based on the kernel.perf_event_mlock_kb + sysctl. This is done only if the user doesn't specify a --mmap-pages value. + +--kernel-syscall-graph:: + Show the kernel callchains on the syscall exit path. + +--max-events=N:: + Stop after processing N events. Note that strace-like events are considered + only at exit time or when a syscall is interrupted, i.e. in those cases this + option is equivalent to the number of lines printed. + +--switch-on EVENT_NAME:: + Only consider events after this event is found. + +--switch-off EVENT_NAME:: + Stop considering events after this event is found. + +--show-on-off-events:: + Show the --switch-on/off events too. + +--max-stack:: + Set the stack depth limit when parsing the callchain, anything + beyond the specified depth will be ignored. Note that at this point + this is just about the presentation part, i.e. the kernel is still + not limiting, the overhead of callchains needs to be set via the + knobs in --call-graph dwarf. + + Implies '--call-graph dwarf' when --call-graph not present on the + command line, on systems where DWARF unwinding was built in. + + Default: /proc/sys/kernel/perf_event_max_stack when present for + live sessions (without --input/-i), 127 otherwise. + +--min-stack:: + Set the stack depth limit when parsing the callchain, anything + below the specified depth will be ignored. Disabled by default. + + Implies '--call-graph dwarf' when --call-graph not present on the + command line, on systems where DWARF unwinding was built in. + +--print-sample:: + Print the PERF_RECORD_SAMPLE PERF_SAMPLE_ info for the + raw_syscalls:sys_{enter,exit} tracepoints, for debugging. + +--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. + +--sort-events:: + Do sorting on batches of events, use when noticing out of order events that + may happen, for instance, when a thread gets migrated to a different CPU + while processing a syscall. + +--libtraceevent_print:: + Use libtraceevent to print tracepoint arguments. By default 'perf trace' uses + the same beautifiers used in the strace-like enter+exit lines to augment the + tracepoint arguments. + +--map-dump:: + Dump BPF maps setup by events passed via -e, for instance the augmented_raw_syscalls + living in tools/perf/examples/bpf/augmented_raw_syscalls.c. For now this + dumps just boolean map values and integer keys, in time this will print in hex + by default and use BTF when available, as well as use functions to do pretty + printing using the existing 'perf trace' syscall arg beautifiers to map integer + arguments to strings (pid to comm, syscall id to syscall name, etc). + + +PAGEFAULTS +---------- + +When tracing pagefaults, the format of the trace is as follows: + +<min|maj>fault [<ip.symbol>+<ip.offset>] => <addr.dso@addr.offset> (<map type><addr level>). + +- min/maj indicates whether fault event is minor or major; +- ip.symbol shows symbol for instruction pointer (the code that generated the + fault); if no debug symbols available, perf trace will print raw IP; +- addr.dso shows DSO for the faulted address; +- map type is either 'd' for non-executable maps or 'x' for executable maps; +- addr level is either 'k' for kernel dso or '.' for user dso. + +For symbols resolution you may need to install debugging symbols. + +Please be aware that duration is currently always 0 and doesn't reflect actual +time it took for fault to be handled! + +When --verbose specified, perf trace tries to print all available information +for both IP and fault address in the form of dso@symbol+offset. + +EXAMPLES +-------- + +Trace only major pagefaults: + + $ perf trace --no-syscalls -F + +Trace syscalls, major and minor pagefaults: + + $ perf trace -F all + + 1416.547 ( 0.000 ms): python/20235 majfault [CRYPTO_push_info_+0x0] => /lib/x86_64-linux-gnu/libcrypto.so.1.0.0@0x61be0 (x.) + + As you can see, there was major pagefault in python process, from + CRYPTO_push_info_ routine which faulted somewhere in libcrypto.so. + +Trace the first 4 open, openat or open_by_handle_at syscalls (in the future more syscalls may match here): + + $ perf trace -e open* --max-events 4 + [root@jouet perf]# trace -e open* --max-events 4 + 2272.992 ( 0.037 ms): gnome-shell/1370 openat(dfd: CWD, filename: /proc/self/stat) = 31 + 2277.481 ( 0.139 ms): gnome-shell/3039 openat(dfd: CWD, filename: /proc/self/stat) = 65 + 3026.398 ( 0.076 ms): gnome-shell/3039 openat(dfd: CWD, filename: /proc/self/stat) = 65 + 4294.665 ( 0.015 ms): sed/15879 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC) = 3 + $ + +Trace the first minor page fault when running a workload: + + # perf trace -F min --max-stack=7 --max-events 1 sleep 1 + 0.000 ( 0.000 ms): sleep/18006 minfault [__clear_user+0x1a] => 0x5626efa56080 (?k) + __clear_user ([kernel.kallsyms]) + load_elf_binary ([kernel.kallsyms]) + search_binary_handler ([kernel.kallsyms]) + __do_execve_file.isra.33 ([kernel.kallsyms]) + __x64_sys_execve ([kernel.kallsyms]) + do_syscall_64 ([kernel.kallsyms]) + entry_SYSCALL_64 ([kernel.kallsyms]) + # + +Trace the next min page page fault to take place on the first CPU: + + # perf trace -F min --call-graph=dwarf --max-events 1 --cpu 0 + 0.000 ( 0.000 ms): Web Content/17136 minfault [js::gc::Chunk::fetchNextDecommittedArena+0x4b] => 0x7fbe6181b000 (?.) + js::gc::FreeSpan::initAsEmpty (inlined) + js::gc::Arena::setAsNotAllocated (inlined) + js::gc::Chunk::fetchNextDecommittedArena (/usr/lib64/firefox/libxul.so) + js::gc::Chunk::allocateArena (/usr/lib64/firefox/libxul.so) + js::gc::GCRuntime::allocateArena (/usr/lib64/firefox/libxul.so) + js::gc::ArenaLists::allocateFromArena (/usr/lib64/firefox/libxul.so) + js::gc::GCRuntime::tryNewTenuredThing<JSString, (js::AllowGC)1> (inlined) + js::AllocateString<JSString, (js::AllowGC)1> (/usr/lib64/firefox/libxul.so) + js::Allocate<JSThinInlineString, (js::AllowGC)1> (inlined) + JSThinInlineString::new_<(js::AllowGC)1> (inlined) + AllocateInlineString<(js::AllowGC)1, unsigned char> (inlined) + js::ConcatStrings<(js::AllowGC)1> (/usr/lib64/firefox/libxul.so) + [0x18b26e6bc2bd] (/tmp/perf-17136.map) + # + +Trace the next two sched:sched_switch events, four block:*_plug events, the +next block:*_unplug and the next three net:*dev_queue events, this last one +with a backtrace of at most 16 entries, system wide: + + # perf trace -e sched:*switch/nr=2/,block:*_plug/nr=4/,block:*_unplug/nr=1/,net:*dev_queue/nr=3,max-stack=16/ + 0.000 :0/0 sched:sched_switch:swapper/2:0 [120] S ==> rcu_sched:10 [120] + 0.015 rcu_sched/10 sched:sched_switch:rcu_sched:10 [120] R ==> swapper/2:0 [120] + 254.198 irq/50-iwlwifi/680 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051f600 len=66 + __dev_queue_xmit ([kernel.kallsyms]) + 273.977 :0/0 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051f600 len=78 + __dev_queue_xmit ([kernel.kallsyms]) + 274.007 :0/0 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051ff00 len=78 + __dev_queue_xmit ([kernel.kallsyms]) + 2930.140 kworker/u16:58/2722 block:block_plug:[kworker/u16:58] + 2930.162 kworker/u16:58/2722 block:block_unplug:[kworker/u16:58] 1 + 4466.094 jbd2/dm-2-8/748 block:block_plug:[jbd2/dm-2-8] + 8050.123 kworker/u16:30/2694 block:block_plug:[kworker/u16:30] + 8050.271 kworker/u16:30/2694 block:block_plug:[kworker/u16:30] + # + +SEE ALSO +-------- +linkperf:perf-record[1], linkperf:perf-script[1] |