Provided by: uftrace_0.8.2-1_amd64 
NAME
uftrace-replay - Print recorded function trace
SYNOPSIS
uftrace replay [options]
DESCRIPTION
This command prints trace data recorded using the uftrace-record(1) command. The traced functions are
printed like a C program in time order.
OPTIONS
--flat Print flat format rather than C-like format. This is usually for debugging and testing purpose.
-F FUNC, --filter=FUNC
Set filter to trace selected functions only. This option can be used more than once. See
FILTERS.
-N FUNC, --notrace=FUNC
Set filter not to trace selected functions (or the functions called underneath them). This option
can be used more than once. See FILTERS.
-T TRG, --trigger=TRG
Set trigger on selected functions. This option can be used more than once. See TRIGGERS.
-t TIME, --time-filter=TIME
Do not show functions which run under the time threshold. If some functions explicitly have the
'trace' trigger applied, those are always traced regardless of execution time.
--tid=TID[,TID,...]
Only print functions called by the given threads. To see the list of threads in the data file,
you can use uftrace report --threads or uftrace info. This option can also be used more than
once.
-D DEPTH, --depth DEPTH
Set trace limit in nesting level.
-f FIELD, --output-fields=FIELD
Customize field in the output. Possible values are: duration, tid, time, delta, elapsed and addr.
Multiple fields can be set by using comma. Special field of 'none' can be used (solely) to hide
all fields. Default is 'duration,tid'. See FIELDS.
-r RANGE, --time-range=RANGE
Only show functions executed within the time RANGE. The RANGE can be <start>~<stop> (separated by
"~") and one of <start> and <stop> can be omitted. The <start> and <stop> are timestamp or
elapsed time if they have <time_unit> postfix, for example '100us'. The timestamp or elapsed time
can be shown with -f time or -f elapsed option respectively.
--disable
Start uftrace with tracing disabled. This is only meaningful when used with a trace_on trigger.
--demangle=TYPE
Use demangled C++ symbol names for filters, triggers, arguments and/or return values. Possible
values are "full", "simple" and "no". Default is "simple" which ignores function arguments and
template parameters.
--column-view
Show each task in separate column. This makes easy to distinguish functions in different tasks.
--column-offset=DEPTH
When --column-view option is used, this option specifies the amount of offset between each task.
Default is 8.
--task-newline
Interleave a new line when task is changed. This makes easy to distinguish functions in different
tasks.
--no-comment
Do not show comments of returned functions.
-k, --kernel
Trace kernel functions (and events) as well as user functions (and events). This options has no
meaning and so is deprecated now. It will always show kernel functions and events if exists. If
you want to hide kernel functions, please use -N .@kernel to filter out all kernel functions.
--kernel-full
Show all kernel functions and events occurred outside of user functions. This option is the
inverse of --kernel-skip-out.
--kernel-skip-out
Do not show kernel functions called outside of user functions. This option is deprecated and set
to true by default.
--kernel-only
Show kernel functions only without user functions.
--event-full
Show all (user) events outside of user functions.
FILTERS
The uftrace tool supports filtering out uninteresting functions. When uftrace is called it receives two
types of function filter; an opt-in filter with -F/--filter and an opt-out filter with -N/--notrace.
These filters can be applied either at record time or replay time.
The first one is an opt-in filter. By default, it doesn't show anything. But when one of the specified
functions is met, printing is started. When the function returns, printing is stopped again.
For example, consider a simple program which calls a(), b() and c() in turn.
$ cat abc.c
void c(void) {
/* do nothing */
}
void b(void) {
c();
}
void a(void) {
b();
}
int main(void) {
a();
return 0;
}
$ gcc -pg -o abc abc.c
Normally uftrace replay will show all the functions from main() to c().
$ uftrace ./abc
# DURATION TID FUNCTION
138.494 us [ 1234] | __cxa_atexit();
[ 1234] | main() {
[ 1234] | a() {
[ 1234] | b() {
3.880 us [ 1234] | c();
5.475 us [ 1234] | } /* b */
6.448 us [ 1234] | } /* a */
8.631 us [ 1234] | } /* main */
But when the -F b filter option is used, it will not show main() or a() but only b() and c(). Note that
the filter was set on uftrace replay, not at record time.
$ uftrace record ./abc
$ uftrace replay -F b
# DURATION TID FUNCTION
[ 1234] | b() {
3.880 us [ 1234] | c();
5.475 us [ 1234] | } /* b */
The second type of filter is opt-out. When used, everything is shown by default, but printing stops once
one of the specified functions is met. When the given function returns, printing is started again.
In the above example, you can omit the function b() and all calls it makes with the -N option.
$ uftrace record ./abc
$ uftrace replay -N b
# DURATION TID FUNCTION
138.494 us [ 1234] | __cxa_atexit();
[ 1234] | main() {
6.448 us [ 1234] | a();
8.631 us [ 1234] | } /* main */
In addition, you can limit the print nesting level with -D option.
$ uftrace record ./abc
$ uftrace replay -D 3
# DURATION TID FUNCTION
138.494 us [ 1234] | __cxa_atexit();
[ 1234] | main() {
[ 1234] | a() {
5.475 us [ 1234] | b();
6.448 us [ 1234] | } /* a */
8.631 us [ 1234] | } /* main */
In the above example, uftrace only prints functions up to a depth of 3, so leaf function c() was omitted.
Note that the -D option also works with -F.
Sometimes it's useful to see long-running functions only. This is good because there are usually many
tiny functions that are not interesting. The -t/--time-filter option implements the time-based filter
that only records functions which run longer than the given threshold. In the above example, the user
might want to see functions running more than 5 microseconds like below:
$ uftrace record ./abc
$ uftrace replay -t 5us
# DURATION TID FUNCTION
138.494 us [ 1234] | __cxa_atexit();
[ 1234] | main() {
[ 1234] | a() {
5.475 us [ 1234] | b();
6.448 us [ 1234] | } /* a */
8.631 us [ 1234] | } /* main */
You can also see replay output with different time threshold for the same recorded data.
$ uftrace replay -t 6us
# DURATION TID FUNCTION
138.494 us [ 1234] | __cxa_atexit();
[ 1234] | main() {
6.448 us [ 1234] | a();
8.631 us [ 1234] | } /* main */
In addition, The -r option can show functions executed within the given time range. When using this
option, you can see TIMESTAMP or ELAPSED fields as well as DURATION and TID.
$ uftrace replay -r 502716.387320101~502716.387322389
# TIMESTAMP DURATION TID FUNCTION
502716.387320101 0.289 us [ 6126] | fgets();
502716.387320584 [ 6126] | get_values_from() {
502716.387320709 0.245 us [ 6126] | strdup();
502716.387321172 0.144 us [ 6126] | strsep();
502716.387321542 0.223 us [ 6126] | atoi();
502716.387321983 0.239 us [ 6126] | atoi();
502716.387322389 1.805 us [ 6126] | } /* get_values_from */
$ uftrace replay -r 40us~ | head -10
# ELAPSED DURATION TID FUNCTION
40.141 us [ 6126] | get_values_from() {
40.269 us 0.249 us [ 6126] | strdup();
40.756 us 0.149 us [ 6126] | strsep();
41.119 us 0.235 us [ 6126] | atoi();
41.578 us 0.211 us [ 6126] | atoi();
41.957 us 1.816 us [ 6126] | } /* get_values_from */
42.124 us 0.220 us [ 6126] | fgets();
42.529 us [ 6126] | get_values_from() {
42.645 us 0.236 us [ 6126] | strdup();
You can also set triggers on filtered functions. See TRIGGERS section below for details.
TRIGGERS
The uftrace tool supports triggering actions on selected function calls with or without filters.
Currently supported triggers are depth, backtrace, trace_on and trace_off. The BNF for trigger
specifications is like below:
<trigger> := <symbol> "@" <actions>
<actions> := <action> | <action> "," <actions>
<action> := "depth="<num> | "backtrace" | "trace_on" | "trace_off" |
"color="<color> | "time="<time_spec> | "filter" | "notrace"
<time_spec> := <num> [ <time_unit> ]
<time_unit> := "ns" | "nsec" | "us" | "usec" | "ms" | "msec" | "s" | "sec" | "m" | "min"
The depth trigger is to change filter depth during execution of the function. It can be used to apply
different filter depths for different functions. And the backtrace trigger is used to print a stack
backtrace at replay time.
The color trigger is to change the color of the function in replay output. The supported colors are red,
green, blue, yellow, magenta, cyan, bold, and gray.
The following example shows how triggers work. We set a filter on function b() with the backtrace action
and change the maximum filter depth under b() to 2.
$ uftrace record ./abc
$ uftrace replay -T 'b@filter,backtrace,depth=2'
# DURATION TID FUNCTION
backtrace [ 1234] | /* [ 0] main */
backtrace [ 1234] | /* [ 1] a */
[ 1234] | b {
3.880 us [ 1234] | c();
5.475 us [ 1234] | } /* b */
The traceon and traceoff actions (the _ can be omitted from trace_on and trace_off) control whether
uftrace shows functions or not. The trigger runs at replay time, not run time, so it can handle kernel
functions as well. Contrast this with triggers used under uftrace record.
The 'time' trigger is to change time filter setting during execution of the function. It can be used to
apply different time filter for different functions.
The 'filter' and 'notrace' triggers have same effect as -F/--filter and -N/--notrace options
respectively.
FIELDS
The uftrace allows for user to customize the replay output with a couple of fields. Here the field means
info on the left side of the pipe (|) character. By default it uses duration and tid fields, but you can
use other fields in any order like:
$ uftrace replay -f time,delta,duration,addr
# TIMESTAMP TIMEDELTA DURATION ADDRESS FUNCTION
74469.340757350 1.583 us 4004d0 | __monstartup();
74469.340762221 4.871 us 0.766 us 4004f0 | __cxa_atexit();
74469.340764847 2.626 us 4006b1 | main() {
74469.340765061 0.214 us 400656 | a() {
74469.340765195 0.134 us 400669 | b() {
74469.340765344 0.149 us 40067c | c() {
74469.340765524 0.180 us 0.742 us 4004b0 | getpid();
74469.340766935 1.411 us 1.591 us 40067c | } /* c */
74469.340767195 0.260 us 2.000 us 400669 | } /* b */
74469.340767372 0.177 us 2.311 us 400656 | } /* a */
74469.340767541 0.169 us 2.694 us 4006b1 | } /* main */
Each field has following meaning:
• tid: task id (obtained by gettid(2))
• duration: function execution time
• time: timestamp at the execution
• delta: difference between two timestamp in a task
• elapsed: elapsed time from the first timestamp
• addr: address of the function
The default value is 'duration,tid'. If given field name starts with "+", then it'll be appended to the
default fields. So "-f +time" is as same as "-f duration,tid,time". And it also accepts a special field
name of 'none' which disables the field display and shows function output only.
SEE ALSO
uftrace(1), uftrace-record(1), uftrace-report(1), uftrace-info(1)
AUTHORS
Namhyung Kim <namhyung@gmail.com>.