Provided by: uftrace_0.9.4-0.2ubuntu1_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.
REPLAY OPTIONS
-f FIELD, --output-fields=FIELD
Customize field in the output. Possible values are: duration, tid, addr, time,
delta, elapsed, task and module. 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.
--flat Print flat format rather than C-like format. This is usually for debugging and
testing purpose.
--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.
--libname
Show libname name along with function name.
COMMON OPTIONS
-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.
-C FUNC, --caller-filter=FUNC
Set filter to trace callers of selected functions only. 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.
-D DEPTH, --depth DEPTH
Set trace limit in nesting level. See FILTERS.
-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. See FILTERS.
--no-libcall
Do not show library calls.
--no-event
Do not show any events.
--match=TYPE
Use pattern match using TYPE. Possible types are regex and glob. Default is
regex.
--disable
Start replay with tracing disabled. This is only meaningful when used with a
trace_on trigger.
COMMON ANALYSIS OPTIONS
--kernel-full
Show all kernel functions and events occurred outside of user functions.
--kernel-only
Show kernel functions only without user functions.
--event-full
Show all (user) events outside of user functions.
--tid=TID[,TID,...]
Only print functions called by the given tasks. To see the list of tasks in the
data file, you can use uftrace report --task or uftrace info. This option can also
be used more than once.
--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.
-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. See FILTERS.
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 */
If users only care about specific functions and want to know how they are called, one can
use the caller filter. It makes the function as leaf and prints the parent functions to
the function.
$ uftrace record ./abc
$ uftrace replay -C b
# DURATION TID FUNCTION
[ 1234] | main() {
[ 1234] | a() {
5.475 us [ 1234] | b();
6.448 us [ 1234] | } /* a */
8.631 us [ 1234] | } /* main */
In the above example, functions not in the calling path were not shown. Also the function
`c' - which is a child of the function `b' - is also hidden.
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 trace_on and trace_off actions (the _ can be omitted as traceon and traceoff) 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
• task: task name (comm)
• module: library or executable name 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>.