UFTRACE-SCRIPT

NAME

uftrace-script - Run a script for recorded function trace

SYNOPSIS

uftrace script (-S|–script) [options] uftrace script (-S|–script)

[options] –record COMMAND

DESCRIPTION

This command runs a script for trace data recorded using the uftrace-record(1) command.

SCRIPT OPTIONS

-S SCRIPT_PATH, --script=SCRIPT_PATH

Run a given script to do additional work at the entry and exit of function while processing recorded trace data. The type of script is detected by the file extension. For example ‘.py’ for python and ‘.lua’ for lua 5.1. See SCRIPT EXECUTION.

--record COMMAND [command-options]

Record a new trace before running a given script.

--no-args

Do not show function arguments and return value.

COMMON OPTIONS

-F FUNC, --filter=FUNC

Set filter to trace selected functions and their children functions. This option can be used more than once. See uftrace-replay(1) for an explanation of filters.

-N FUNC, --notrace=FUNC

Set filter not to trace selected functions and their children functions. This option can be used more than once. See uftrace-replay(1) for an explanation of filters.

-C FUNC, --caller-filter=FUNC

Set filter to trace callers of selected functions only. This option can be used more than once. See uftrace-replay(1) for an explanation of filters.

-T TRG, --trigger=TRG

Set trigger on selected functions. This option can be used more than once. See ‘uftrace-replay’ for details.

-D DEPTH, --depth DEPTH

Set trace limit in nesting level.

-t TIME, --time-filter=TIME

Do not run script for functions which run under the time threshold. If some functions explicitly have the ‘trace’ trigger applied, those are always traced regardless of execution time.

-Z SIZE, --size-filter=SIZE

Do not show functions smaller than SIZE bytes.

-L LOCATION, --loc-filter=LOCATION

Set filter to trace selected source locations. This option can be used more than once.

--no-libcall

Do not run script for library calls.

--match=TYPE

Use pattern match using TYPE. Possible types are regex and glob. Default is regex.

--with-syms=DIR

Read symbol data from the .sym files in DIR directory instead of the binary. This can be useful to deal with stripped binaries. The file name of the main binary should be the same when saved and used.

COMMON ANALYSIS OPTIONS

-H FUNC, --hide=FUNC

Set filter not to trace selected functions. It doesn’t affect their subtrees, but hides only the given functions. This option can be used more than once. See uftrace-replay(1) for an explanation of filters.

--kernel-full

Run script all kernel functions and events occurred outside of user functions.

--kernel-only

Run script kernel functions only without user functions.

--tid=TID[,TID,...]

Run script only for 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

Run script only for 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 in uftrace replay(1).

SCRIPT EXECUTION

The uftrace tool supports script execution for each function entry and exit. The supported script types are Python 2.7, Python 3 and Lua 5.1 as of now.

The user can write five functions. ‘uftrace_entry’ and ‘uftrace_exit’ are executed whenever each function is executed at the entry and exit. However ‘uftrace_begin’ and ‘uftrace_end’ are only executed once when the target program begins and ends. ‘uftrace_event’ is called when it sees an event.

$ cat scripts/simple.py
def uftrace_begin(ctx):
print("program begins...")

def uftrace_entry(ctx):
func = ctx["name"]
print("entry : " + func + "()")

def uftrace_exit(ctx):
func = ctx["name"]
print("exit : " + func + "()")

def uftrace_event(ctx):
name = ctx["name"]
print("event : " + name)

def uftrace_end():
print("program is finished")

The ‘ctx’ variable is a dictionary type that contains the below information.

/* context information passed to uftrace_entry(ctx) and uftrace_exit(ctx) */
script_context = {
int tid;
int depth;
long timestamp;
long duration; # exit only
long address;
string name;
list args; # entry only (if available)
value retval; # exit only (if available)
};

/* context information passed to uftrace_begin(ctx) */
script_context = {
bool record; # True if it runs at record time, otherwise False
string version; # uftrace version info
list cmds; # execution commands
};

The above script can be executed while reading the recorded data. The usage is as follows:

$ uftrace record -F main tests/t-abc

$ uftrace script -S scripts/simple.py
program begins...
entry : main()
entry : a()
entry : b()
entry : c()
entry : getpid()
exit : getpid()
exit : c()
exit : b()
exit : a()
exit : main()
program is finished

The below is another example that shows the different output compared to previous one for the same recorded data. The output looks similar to uftrace replay this time.

$ uftrace script -S scripts/replay.py
# DURATION TID FUNCTION
[25794] | main() {
[25794] | a() {
[25794] | b() {
[25794] | c() {
[25794] | getpid() {
11.037 us [25794] | } /* getpid */
44.752 us [25794] | } /* c */
70.924 us [25794] | } /* b */
98.191 us [25794] | } /* a */
124.329 us [25794] | } /* main */

The script above can be modified to do more output customization.

A script can have an optional “UFTRACE_FUNCS” list which can have name (or pattern depending on the –match option) of functions to run the script. If it exists, only matched functions will run the script. For example, if you add following lines to the script, it will run only for functions with a single letter name.

$ echo 'UFTRACE_FUNCS = [ "^.$" ]' >> replay.py
$ uftrace script -S replay.py
# DURATION TID FUNCTION
[25794] | a() {
[25794] | b() {
[25794] | c() {
44.752 us [25794] | } /* c */
70.924 us [25794] | } /* b */
98.191 us [25794] | } /* a */

Also a script can have options for record if it requires some form of data (i.e. function argument or return value). A comment line started with “uftrace-option:” will provide (a part of) such options when recording.

$ cat arg.py
#
# uftrace-option: -A a@arg1 -R b@retval
#
def uftrace_entry(ctx):
if "args" in ctx:
print(ctx["name"] + " has args")
def uftrace_exit(ctx):
if "retval" in ctx:
print(ctx["name"] + " has retval")

$ uftrace record -S arg.py abc
a has args
b has retval
$ uftrace script -S arg.py
a has args
b has retval

Also a script can handle event records and optional event data in “args”. The argument is a string containing KEY=VALUE pairs. Currently it only works with uftrace script and not for record.

$ cat event.py
def uftrace_entry(ctx):
pass
def uftrace_exit(ctx):
pass
def uftrace_event(ctx):
if "args" in ctx:
print(ctx["name"] + " ::: " + ctx["args"])
else:
print(ctx["name"])

$ uftrace record -T a@read=proc/statm abc
$ uftrace script -S event.py
read:proc/statm ::: vmsize=31060KB vmrss=15412KB shared=11064KB
diff:proc/statm ::: vmsize=+0KB vmrss=+0KB shared=+0KB

SEE ALSO

uftrace(1), uftrace-record(1), uftrace-replay(1), uftrace-live(1)

AUTHORS

Honggyu Kim <honggyu.kp@gmail.com>, Namhyung Kim <namhyung@gmail.com>.