ufuncgraph

ufuncgraph

bpf(2)-based ftrace(1)-like function graph tracer for userspace processes.

Limits:

1. Only Works for Go programs for now;
2. .symtab ELF section is required, and .debug_info section is preferable;
3. The Go binary must be built using static linking;
4. Running on x86-64 little-endian Linux only;
5. Kernel version has to support bpf(2) and uprobe, and I developped it on 5.14.0;

Example

Let's trace dockerd to see how it handles docker stop:

Type the command:

sudo ufuncgraph -d 1 ./bundles/binary-daemon/dockerd '!runtime.*' '!context.*' '!*vendor*' 'github.com/docker/docker/daemon.(*Daemon).containerStop(id=+0(+64(%rdi)):c256, name=+0(+200(%rdi)):c256, name_len=+208(%rdi):s32)'

Explanations:

1. -d 1: search the functions called by github.com/docker/docker/daemon.(*Daemon).containerStop, and only search for one layer;
2. !runtime.*: ignore the functions matching the wildcard runtime.*;
3. !context.*: ignore the functions matching the wildcard context.*;
4. !*vendor*: ignore the functions matching the wildcard *vendor*;
5. github.com/docker/docker/daemon.(*Daemon).containerStop(id=+0(+64(%rdi)):c256, name=+0(+200(%rdi)):c256, name_len=+208(%rdi):s32): attach the function github.com/docker/docker/daemon.(*Daemon).containerStop, and fetch the arguments id, name and name_len using Linux uprobe_tracer's FETCHARGS syntax.

And will get the results:

Use cases

1. Wall time profiling;
2. Execution flow observing;

Wall time profiling case

Chinese version: https://roamresearch.com/#/app/FEZ/page/C-xt1C2M1

Execution flow observing

Chinese version: https://roamresearch.com/#/app/FEZ/page/ya-t0xN8m