Demonstrations of ucalls.

ucalls summarizes method calls in various high-level languages, including Java,

Python, Ruby, PHP, and Linux system calls. It displays statistics on the most

frequently called methods, as well as the latency (duration) of these methods.

Through the syscalls support, ucalls can provide basic information on a

process' interaction with the system including syscall counts and latencies.

This can then be used for further exploration with other BCC tools like trace,

argdist, biotop, fileslower, and others.

For example, to trace method call latency in a Java application:

# ucalls -L $(pidof java)

Tracing calls in process 26877 (language: java)... Ctrl-C to quit.

METHOD # CALLS TIME (us)

java/io/BufferedInputStream.getBufIfOpen 1 7.00

slowy/App.isSimplePrime 8970 8858.35

slowy/App.isDivisible 3228196 3076985.12

slowy/App.isPrime 8969 4841017.64

^C

To trace only syscalls in a particular process and print the top 10 most

frequently-invoked ones:

# ucalls -ST 10 3018

Attached 375 kernel probes for syscall tracing.

Tracing calls in process 3018 (language: none)... Ctrl-C to quit.

METHOD # CALLS

sys_rt_sigaction 4

SyS_rt_sigprocmask 4

sys_mprotect 5

sys_read 22

SyS_write 39

SyS_epoll_wait 42

sys_futex 177

SyS_mmap 180

sys_mmap_pgoff 181

sys_munmap 817

^C

Detaching kernel probes, please wait...

To print only the top 5 methods and report times in milliseconds (the default

is microseconds):

# ucalls -mT 5 $(pidof python)

Tracing calls in process 26914 (language: python)... Ctrl-C to quit.

METHOD # CALLS

<stdin>.<module> 1

<stdin>.fibo 14190928

^C

USAGE message:

# ./ucalls.py -h

usage: ucalls.py [-h] [-l {java,python,ruby,php,none}] [-T TOP] [-L] [-S] [-v]

[-m]

pid [interval]

Summarize method calls in high-level languages.

positional arguments:

pid process id to attach to

interval print every specified number of seconds

optional arguments:

-h, --help show this help message and exit

-l {java,python,ruby,php,none}, --language {java,python,ruby,php,none}

language to trace (if none, trace syscalls only)

-T TOP, --top TOP number of most frequent/slow calls to print

-L, --latency record method latency from enter to exit (except

recursive calls)

-S, --syscalls record syscall latency (adds overhead)

-v, --verbose verbose mode: print the BPF program (for debugging

purposes)

-m, --milliseconds report times in milliseconds (default is microseconds)

examples:

./ucalls -l java 185 # trace Java calls and print statistics on ^C

./ucalls -l python 2020 1 # trace Python calls and print every second

./ucalls -l java 185 -S # trace Java calls and syscalls

./ucalls 6712 -S # trace only syscall counts

./ucalls -l ruby 1344 -T 10 # trace top 10 Ruby method calls

./ucalls -l ruby 1344 -L # trace Ruby calls including latency

./ucalls -l php 443 -LS # trace PHP calls and syscalls with latency

./ucalls -l python 2020 -mL # trace Python calls including latency in ms