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trace-cmd-report - Man Page

show in ASCII a trace created by trace-cmd record


trace-cmd report [Options] [input-file]


The trace-cmd(1) report command will output a human readable report of a trace created by trace-cmd record.


-i input-file

By default, trace-cmd report will read the file trace.dat. But the -i option open up the given input-file instead. Note, the input file may also be specified as the last item on the command line.


This outputs the endianess of the file. trace-cmd report is smart enough to be able to read big endian files on little endian machines, and vise versa.


This outputs the list of all functions that have been mapped in the trace.dat file. Note, this list may contain functions that may not appear in the trace, as it is the list of mappings to translate function addresses into function names.


This outputs the list of "trace_printk()" data. The raw trace data points to static pointers in the kernel. This must be stored in the trace.dat file.


This lists the possible events in the file (but this list is not necessarily the list of events in the file).


This will list the event formats that are stored in the trace.dat file.

--event regex

This will print events that match the given regex. If a colon is specified, then the characters before the colon will be used to match the system and the characters after the colon will match the event.

trace-cmd report --event sys:read
The above will only match events where the system name contains "sys"
and the event name contains "read".
trace-cmd report --event read
The above will match all events that contain "read" in its name. Also it
may list all events of a system that contains "read" as well.

This will parse the event format strings that are stored in the trace.dat file and return whether the formats can be parsed correctly. It will load plugins unless -N is specified.


Print the full timestamp. The timestamps in the data file are usually recorded to the nanosecond. But the default display of the timestamp is only to the microsecond. To see the full timestamp, add the -t option.

-F filter

Add a filter to limit what events are displayed. Filters defined after an input file (specified with -i) only apply to that input file. Filters provided before any input file is given are considered global and apply to all input files.

The format of the filter is:
    <events> ':' <filter>
    <events> = SYSTEM'/'EVENT  | SYSTEM | EVENT | <events> ',' <events>
    <filter> = EVENT_FIELD <op> <value> | <filter> '&&' <filter> |
               <filter> '||' <filter> | '(' <filter> ')' | '!' <filter>
    <op> = '==' | '!=' | '>=' | '<=' | '>' | '<' | '&' | '|' | '^' |
           '+' | '-' | '*' | '/' | '%'
    <value> = NUM | STRING | EVENT_FIELD
SYSTEM is the name of the system to filter on. If the EVENT is left out,
then it applies to all events under the SYSTEM. If only one string is used
without the '/' to deliminate between SYSTEM and EVENT, then the filter
will be applied to all systems and events that match the given string.
Whitespace is ignored, such that "sched:next_pid==123" is equivalent to
"sched : next_pid == 123".
STRING is defined with single or double quotes (single quote must end with
single quote, and double with double). Whitespace within quotes are not
The representation of a SYSTEM or EVENT may also be a regular expression
as defined by 'regcomp(3)'.
The EVENT_FIELD is the name of the field of an event that is being
filtered. If the event does not contain the EVENT_FIELD, that part of the
equation will be considered false.
    -F 'sched : bogus == 1 || common_pid == 2'
The "bogus == 1" will always evaluate to FALSE because no event has a
field called "bogus", but the "common_pid == 2" will still be evaluated
since all events have the field "common_pid". Any "sched" event that was
traced by the process with the PID of 2 will be shown.
Note, the EVENT_FIELD is the field name as shown by an events format
(as displayed with *--events*), and not what is found in the output.
If the output shows "ID:foo" but the field that "foo" belongs to was
called "name" in the event format, then "name" must be used in the filter.
The same is true about values. If the value that is displayed is converted
by to a string symbol, the filter checks the original value and not the
value displayed. For example, to filter on all tasks that were in the
running state at a context switch:
    -F 'sched/sched_switch : prev_state==0'
Although the output displays 'R', having 'prev_stat=="R"' will not work.
Note: You can also specify 'COMM' as an EVENT_FIELD. This will use the
task name (or comm) of the record to compare. For example, to filter out
all of the "trace-cmd" tasks:
    -F '.*:COMM != "trace-cmd"'

Do not print events where the HARDIRQ latency flag is set. This will filter out most events that are from interrupt context. Note, it may not filter out function traced functions that are in interrupt context but were called before the kernel "in interrupt" flag was set.


Do not print events where the SOFTIRQ latency flag is set. This will filter out most events that are from soft interrupt context.


This causes the following filters of -F to filter out the matching events.

    -v -F 'sched/sched_switch : prev_state == 0'
Will not display any sched_switch events that have a prev_state of 0.
Removing the *-v* will only print out those events.

Test the filters of -F. After processing a filter string, the resulting filter will be displayed for each event. This is useful for using a filter for more than one event where a field may not exist in all events. Also it can be used to make sure there are no misspelled event field names, as they will simply be ignored. -T is ignored if -F is not specified.


Show verbose messages (see --verbose but only for the numbers)


This will not load system wide plugins. It loads "local only". That is what it finds in the ~/.trace-cmd/plugins directory.


This will not load any plugins.

-n event-re

This will cause all events that match the option to ignore any registered handler (by the plugins) to print the event. The normal event will be printed instead. The event-re is a regular expression as defined by regcomp(3).


With the --profile option, "trace-cmd report" will process all the events first, and then output a format showing where tasks have spent their time in the kernel, as well as where they are blocked the most, and where wake up latencies are.

See trace-cmd-profile(1) for more details and examples.

Set interrupt (soft and hard) events as global (associated to CPU instead of tasks). Only works for --profile.

-H event-hooks

Add custom event matching to connect any two events together.

See trace-cmd-profile(1) for format.

This will show the events in "raw" format. That is, it will ignore the event’s print formatting and just print the contents of each field.

-r event-re

This will cause all events that match the option to print its raw fields. The event-re is a regular expression as defined by regcomp(3).


This adds a "latency output" format. Information about interrupts being disabled, soft irq being disabled, the "need_resched" flag being set, preempt count, and big kernel lock are all being recorded with every event. But the default display does not show this information. This option will set display this information with 6 characters. When one of the fields is zero or N/A a '.\' is shown.

      <idle>-0       0d.h1. 106467.859747: function:             ktime_get <-- tick_check_idle
The 0d.h1. denotes this information.
It starts with a number. This represents the CPU number that the event occurred
The second character is one of the following:
'd' - Interrupts are disabled
'.' - Interrupts are enabled
'X' - Has flags that are not yet known by trace-cmd
The third character is the "need rescheduling" flag.
'N' - A schedule is set to take place
'.' - No scheduling is set
The fourth character represents the context the event was in when it triggered
'h' - Hard interrupt context
's' - Soft interrupt context
'H' - Hard interrupt context that interrupted a soft interrupt
'.' - Normal context
The next is a number (should be less than 10), that represents the preemption
depth (the number of times preempt_disable() is called without preempt_enable()).
'.' means preemption is enabled.
On some systems, "migrate disable" may exist, in which case a number will be
shown for that, or '.' meaning migration is enabled.
If lockdep in enabled on the system, then the number represents the depth of
locks that are held when the event triggered. '.' means no locks are held.

If both the sched_switch and sched_wakeup events are enabled, then this option will report the latency between the time the task was first woken, and the time it was scheduled in.


Quiet non critical warnings.


Pass options to the trace-cmd plugins that are loaded.

-O plugin:var=value
The 'plugin:' and '=value' are optional. Value may be left off for options
that are boolean. If the 'plugin:' is left off, then any variable that matches
in all plugins will be set.
Example:  -O fgraph:tailprint
--cpu <cpu list>

List of CPUs, separated by "," or ":", used for filtering the events. A range of CPUs can be specified using "cpuX-cpuY" notation, where all CPUs in the range between cpuX and cpuY will be included in the list. The order of CPUs in the list must be from lower to greater.

Example:  "--cpu 0,3" - show events from CPUs 0 and 3
          "--cpu 2-4" - show events from CPUs 2, 3 and 4

List the CPUs that have data in the trace file then exit.


Show the timestamp of the first event of all CPUs that have data.


Show the timestamp of the last event of all CPUs that have data.


If the trace.dat file recorded the final stats (outputed at the end of record) the --stat option can be used to retrieve them.


If the trace.dat file recorded uname during the run, this will retrieve that information.


If the trace.dat file recorded the version of the executable used to create it, report that version.

--ts-offset offset

Add (or subtract if negative) an offset for all timestamps of the previous data file specified with -i. This is useful to merge sort multiple trace.dat files where the difference in the timestamp is known. For example if a trace is done on a virtual guest, and another trace is done on the host. If the host timestamp is 1000 units ahead of the guest, the following can be done:

trace-cmd report -i host.dat --ts-offset -1000 -i guest.dat
This will subtract 1000 timestamp units from all the host events as it merges
with the guest.dat events. Note, the units is for the raw units recorded in
the trace. If the units are nanoseconds, the addition (or subtraction) from
the offset will be nanoseconds even if the displayed units are microseconds.
--ts2secs HZ

Convert the current clock source into a second (nanosecond resolution) output. When using clocks like x86-tsc, if the frequency is known, by passing in the clock frequency, this will convert the time to seconds.

This option affects any trace.dat file given with *-i* proceeding it.
If this option comes before any *-i* option, then that value becomes
the default conversion for all other trace.dat files. If another
--ts2secs option appears after a *-i* trace.dat file, than that option
will override the default value.
Example: On a 3.4 GHz machine
trace-cmd record -p function -C x86-tsc
trace-cmd report --ts2ns 3400000000
The report will convert the cycles timestamps into a readable second
display. The default display resolution is microseconds, unless *-t*
is used.
The value of --ts-offset must still be in the raw timestamp units, even
with this option. The offset will be converted as well.

Show the time differences between events. The difference will appear in parenthesis just after the timestamp.


Make sure no timestamp goes backwards, and if it does, print out a warning message of the fact.


Ignore converting the timestamps to the date set by trace-cmd record(3) --date option.


Display raw timestamps, without any corrections.


Display timestamps aligned to the first event.


Set the log level. Supported log levels are "none", "crit", "err", "warn", "info", "debug", "all" or their identifiers "0", "1", "2", "3", "4", "5", "6". Setting the log level to specific value enables all logs from that and all previous levels. The level will default to "info" if one is not specified.

Example: enable all critical, error and warning logs
trace-cmd report --verbose=warning


Using a trace.dat file that was created with:

    # trace-cmd record -p function -e all sleep 5

The default report shows:

 # trace-cmd report
       trace-cmd-16129 [002] 158126.498411: function: __mutex_unlock_slowpath <-- mutex_unlock
       trace-cmd-16131 [000] 158126.498411: kmem_cache_alloc: call_site=811223c5 ptr=0xffff88003ecf2b40 bytes_req=272 bytes_alloc=320 gfp_flags=GFP_KERNEL|GFP_ZERO
       trace-cmd-16130 [003] 158126.498411: function:             do_splice_to <-- sys_splice
           sleep-16133 [001] 158126.498412: function: inotify_inode_queue_event <-- vfs_write
       trace-cmd-16129 [002] 158126.498420: lock_release: 0xffff88003f1fa4f8 &sb->s_type->i_mutex_key
       trace-cmd-16131 [000] 158126.498421: function: security_file_alloc <-- get_empty_filp
           sleep-16133 [001] 158126.498422: function: __fsnotify_parent <-- vfs_write
       trace-cmd-16130 [003] 158126.498422: function: rw_verify_area <-- do_splice_to
       trace-cmd-16131 [000] 158126.498424: function: cap_file_alloc_security <-- security_file_alloc
       trace-cmd-16129 [002] 158126.498425: function: syscall_trace_leave <-- int_check_syscall_exit_work
           sleep-16133 [001] 158126.498426: function: inotify_dentry_parent_queue_event <-- vfs_write
       trace-cmd-16130 [003] 158126.498426: function: security_file_permission <-- rw_verify_area
       trace-cmd-16129 [002] 158126.498428: function: audit_syscall_exit <-- syscall_trace_leave

To see everything but the function traces:

 # trace-cmd report -v -F 'function'
       trace-cmd-16131 [000] 158126.498411: kmem_cache_alloc: call_site=811223c5 ptr=0xffff88003ecf2b40 bytes_req=272 bytes_alloc=320 gfp_flags=GFP_KERNEL|GFP_ZERO
       trace-cmd-16129 [002] 158126.498420: lock_release: 0xffff88003f1fa4f8 &sb->s_type->i_mutex_key
       trace-cmd-16130 [003] 158126.498436: lock_acquire: 0xffffffff8166bf78 read all_cpu_access_lock
       trace-cmd-16131 [000] 158126.498438: lock_acquire: 0xffff88003df5b520 read &fs->lock
       trace-cmd-16129 [002] 158126.498446: kfree: call_site=810a7abb ptr=0x0
       trace-cmd-16130 [003] 158126.498448: lock_acquire: 0xffff880002250a80 &per_cpu(cpu_access_lock, cpu)
       trace-cmd-16129 [002] 158126.498450: sys_exit_splice:      0xfffffff5
       trace-cmd-16131 [000] 158126.498454: lock_release: 0xffff88003df5b520 &fs->lock
           sleep-16133 [001] 158126.498456: kfree: call_site=810a7abb ptr=0x0
           sleep-16133 [001] 158126.498460: sys_exit_write:       0x1
       trace-cmd-16130 [003] 158126.498462: kmalloc: call_site=810bf95b ptr=0xffff88003dedc040 bytes_req=24 bytes_alloc=32 gfp_flags=GFP_KERNEL|GFP_ZERO

To see only the kmalloc calls that were greater than 1000 bytes:

 #trace-cmd report -F 'kmalloc: bytes_req > 1000'
          <idle>-0     [000] 158128.126641: kmalloc: call_site=81330635 ptr=0xffff88003c2fd000 bytes_req=2096 bytes_alloc=4096 gfp_flags=GFP_ATOMIC

To see wakeups and sched switches that left the previous task in the running state:

 # trace-cmd report -F 'sched: prev_state == 0 || (success == 1)'
       trace-cmd-16132 [002] 158126.499951: sched_wakeup: comm=trace-cmd pid=16129 prio=120 success=1 target_cpu=002
       trace-cmd-16132 [002] 158126.500401: sched_switch: prev_comm=trace-cmd prev_pid=16132 prev_prio=120 prev_state=R ==> next_comm=trace-cmd next_pid=16129 next_prio=120
          <idle>-0     [003] 158126.500585: sched_wakeup: comm=trace-cmd pid=16130 prio=120 success=1 target_cpu=003
          <idle>-0     [003] 158126.501241: sched_switch: prev_comm=swapper prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=trace-cmd next_pid=16130 next_prio=120
       trace-cmd-16132 [000] 158126.502475: sched_wakeup: comm=trace-cmd pid=16131 prio=120 success=1 target_cpu=000
       trace-cmd-16131 [002] 158126.506516: sched_wakeup: comm=trace-cmd pid=16129 prio=120 success=1 target_cpu=002
          <idle>-0     [003] 158126.550110: sched_switch: prev_comm=swapper prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=trace-cmd next_pid=16130 next_prio=120
       trace-cmd-16131 [003] 158126.570243: sched_wakeup: comm=trace-cmd pid=16129 prio=120 success=1 target_cpu=003
       trace-cmd-16130 [002] 158126.618202: sched_switch: prev_comm=trace-cmd prev_pid=16130 prev_prio=120 prev_state=R ==> next_comm=yum-updatesd next_pid=3088 next_prio=1 20
       trace-cmd-16129 [003] 158126.622379: sched_wakeup: comm=trace-cmd pid=16131 prio=120 success=1 target_cpu=003
       trace-cmd-16129 [000] 158126.649287: sched_wakeup: comm=trace-cmd pid=16131 prio=120 success=1 target_cpu=000

The above needs a little explanation. The filter specifies the "sched" subsystem, which includes both sched_switch and sched_wakeup events. Any event that does not have the format field "prev_state" or "success", will evaluate those expressions as FALSE, and will not produce a match. Using "||" will have the "prev_state" test happen for the "sched_switch" event and the "success" test happen for the "sched_wakeup" event.

  # trace-cmd report -w -F 'sched_switch, sched_wakeup.*'
       trace-cmd-16130 [003] 158131.580616: sched_wakeup: comm=trace-cmd pid=16131 prio=120 success=1 target_cpu=003
       trace-cmd-16129 [000] 158131.581502: sched_switch: prev_comm=trace-cmd prev_pid=16129 prev_prio=120 prev_state=S ==> next_comm=trace-cmd next_pid=16131 next_prio=120 Latency: 885.901 usecs
       trace-cmd-16131 [000] 158131.582414: sched_wakeup: comm=trace-cmd pid=16129 prio=120 success=1 target_cpu=000
       trace-cmd-16132 [001] 158131.583219: sched_switch: prev_comm=trace-cmd prev_pid=16132 prev_prio=120 prev_state=S ==> next_comm=trace-cmd next_pid=16129 next_prio=120 Latency: 804.809 usecs
           sleep-16133 [002] 158131.584121: sched_wakeup: comm=trace-cmd pid=16120 prio=120 success=1 target_cpu=002
       trace-cmd-16129 [001] 158131.584128: sched_wakeup: comm=trace-cmd pid=16132 prio=120 success=1 target_cpu=001
           sleep-16133 [002] 158131.584275: sched_switch: prev_comm=sleep prev_pid=16133 prev_prio=120 prev_state=R ==> next_comm=trace-cmd next_pid=16120 next_prio=120 Latency: 153.915 usecs
       trace-cmd-16130 [003] 158131.585284: sched_switch: prev_comm=trace-cmd prev_pid=16130 prev_prio=120 prev_state=S ==> next_comm=trace-cmd next_pid=16132 next_prio=120 Latency: 1155.677 usecs

Average wakeup latency: 26626.656 usecs

The above trace produces the wakeup latencies of the tasks. The "sched_switch" event reports each individual latency after writing the event information. At the end of the report, the average wakeup latency is reported.

  # trace-cmd report -w -F 'sched_switch, sched_wakeup.*: prio < 100 || next_prio < 100'
          <idle>-0     [003] 158131.516753: sched_wakeup: comm=ksoftirqd/3 pid=13 prio=49 success=1 target_cpu=003
          <idle>-0     [003] 158131.516855: sched_switch: prev_comm=swapper prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=ksoftirqd/3 next_pid=13 next_prio=49 Latency: 101.244 usecs
          <idle>-0     [003] 158131.533781: sched_wakeup: comm=ksoftirqd/3 pid=13 prio=49 success=1 target_cpu=003
          <idle>-0     [003] 158131.533897: sched_switch: prev_comm=swapper prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=ksoftirqd/3 next_pid=13 next_prio=49 Latency: 115.608 usecs
          <idle>-0     [003] 158131.569730: sched_wakeup: comm=ksoftirqd/3 pid=13 prio=49 success=1 target_cpu=003
          <idle>-0     [003] 158131.569851: sched_switch: prev_comm=swapper prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=ksoftirqd/3 next_pid=13 next_prio=49 Latency: 121.024 usecs

Average wakeup latency: 110.021 usecs

The above version will only show the wakeups and context switches of Real Time tasks. The prio used inside the kernel starts at 0 for highest priority. That is prio 0 is equivalent to user space real time priority 99, and priority 98 is equivalent to user space real time priority 1. Prios less than 100 represent Real Time tasks.

An example of the profile:

 # trace-cmd record --profile sleep 1
 # trace-cmd report --profile --comm sleep
task: sleep-21611
  Event: sched_switch:R (1) Total: 99442 Avg: 99442 Max: 99442 Min:99442
     <stack> 1 total:99442 min:99442 max:99442 avg=99442
       => ftrace_raw_event_sched_switch (0xffffffff8105f812)
       => __schedule (0xffffffff8150810a)
       => preempt_schedule (0xffffffff8150842e)
       => ___preempt_schedule (0xffffffff81273354)
       => cpu_stop_queue_work (0xffffffff810b03c5)
       => stop_one_cpu (0xffffffff810b063b)
       => sched_exec (0xffffffff8106136d)
       => do_execve_common.isra.27 (0xffffffff81148c89)
       => do_execve (0xffffffff811490b0)
       => SyS_execve (0xffffffff811492c4)
       => return_to_handler (0xffffffff8150e3c8)
       => stub_execve (0xffffffff8150c699)
  Event: sched_switch:S (1) Total: 1000506680 Avg: 1000506680 Max: 1000506680 Min:1000506680
     <stack> 1 total:1000506680 min:1000506680 max:1000506680 avg=1000506680
       => ftrace_raw_event_sched_switch (0xffffffff8105f812)
       => __schedule (0xffffffff8150810a)
       => schedule (0xffffffff815084b8)
       => do_nanosleep (0xffffffff8150b22c)
       => hrtimer_nanosleep (0xffffffff8108d647)
       => SyS_nanosleep (0xffffffff8108d72c)
       => return_to_handler (0xffffffff8150e3c8)
       => tracesys_phase2 (0xffffffff8150c304)
  Event: sched_wakeup:21611 (1) Total: 30326 Avg: 30326 Max: 30326 Min:30326
     <stack> 1 total:30326 min:30326 max:30326 avg=30326
       => ftrace_raw_event_sched_wakeup_template (0xffffffff8105f653)
       => ttwu_do_wakeup (0xffffffff810606eb)
       => ttwu_do_activate.constprop.124 (0xffffffff810607c8)
       => try_to_wake_up (0xffffffff8106340a)

See Also

trace-cmd(1), trace-cmd-record(1), trace-cmd-start(1), trace-cmd-stop(1), trace-cmd-extract(1), trace-cmd-reset(1), trace-cmd-split(1), trace-cmd-list(1), trace-cmd-listen(1), trace-cmd-profile(1)


Written by Steven Rostedt, <rostedt@goodmis.org[1]>




Copyright (C) 2010 Red Hat, Inc. Free use of this software is granted under the terms of the GNU Public License (GPL).




Referenced By

trace-cmd(1), trace-cmd-agent(1), trace-cmd-attach(1), trace-cmd-check-events(1), trace-cmd-clear(1), trace-cmd.dat.v6(5), trace-cmd.dat.v7(5), trace-cmd-extract(1), trace-cmd-hist(1), trace-cmd-list(1), trace-cmd-listen(1), trace-cmd-mem(1), trace-cmd-profile(1), trace-cmd-record(1), trace-cmd-reset(1), trace-cmd-restore(1), trace-cmd-set(1), trace-cmd-show(1), trace-cmd-snapshot(1), trace-cmd-split(1), trace-cmd-stack(1), trace-cmd-start(1), trace-cmd-stat(1), trace-cmd-stop(1), trace-cmd-stream(1).

06/23/2024 libtracefs Manual