我试图这样做:我通过iperf发送数据包 - 一个开源工具从一台机器到另一台机器,我想跟踪写入系统或发送呼叫。请帮助我这样做,如果有人可以引导通过Ftrace框架跟踪系统调用,否则任何其他跟踪工具都会很好。
困难的部分是确切地知道要跟踪的内容,这样您只能看到所需的结果,但跟踪本身非常简单:
要查看结果:
vi / sys / kernel / debug / tracing / trace
strace
如果你只是追踪一个过程,为什么不使用strace
?它甚至可以连接到正在运行的进程:How does strace connect to an already running process?
对于ftrace,使用echo none > /sys/kernel/debug/tracing/current_tracer
来跟踪系统调用
至少从Linux 4.15开始,如果你使用function_graph
代替,那么除了系统调用之外,它还显示了大量的功能。
你可以通过过滤解决这个问题,但只使用nop
更简单:How to trace just system call events with ftrace without showing any other functions in the Linux kernel?
使用sudo
运行:
#!/bin/sh
set -eux
d=debug/tracing
mkdir -p debug
if ! mountpoint -q debug; then
mount -t debugfs nodev debug
fi
# Stop tracing.
echo 0 > "${d}/tracing_on"
# Clear previous traces.
echo > "${d}/trace"
# Find the tracer name.
cat "${d}/available_tracers"
# Disable tracing functions, show only system call events.
echo nop > "${d}/current_tracer"
# Find the event name with.
grep write "${d}/available_events"
# Enable tracing write.
# Both statements below seem to do the exact same thing,
# just with different interfaces.
# https://www.kernel.org/doc/html/v4.18/trace/events.html
echo sys_enter_write > "${d}/set_event"
# echo 1 > "${d}/events/syscalls/sys_enter_write/enable"
# Start tracing.
echo 1 > "${d}/tracing_on"
# Generate two write calls by two different processes.
rm -rf /tmp/a /tmp/b
printf a > /tmp/a
printf b > /tmp/b
# View the trace.
cat "${d}/trace"
# Stop tracing.
echo 0 > "${d}/tracing_on"
umount debug
和示例输出:
# tracer: nop
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / delay
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# | | | |||| | |
a.sh-18135 [004] .... 11152.454767: sys_write(fd: 2, buf: 5558769acc00, count: 2)
a.sh-18135 [004] .... 11152.454777: sys_write(fd: 2, buf: 555877f6a968, count: 2)
a.sh-18135 [004] .... 11152.454785: sys_write(fd: 2, buf: 555877f6a968, count: 4)
a.sh-18135 [004] .... 11152.454793: sys_write(fd: 2, buf: 555877f6a968, count: 7)
a.sh-18135 [004] .... 11152.454801: sys_write(fd: 2, buf: 555877f6a968, count: 7)
a.sh-18135 [004] .... 11152.454807: sys_write(fd: 2, buf: 7ffc5f3f2be7, count: 1)
gnome-terminal--3419 [005] .... 11152.454833: sys_write(fd: 4, buf: 7ffe4f3a61c0, count: 8)
gnome-terminal--3419 [005] .... 11152.454862: sys_write(fd: 4, buf: 7ffe4f3a61c0, count: 8)
gnome-terminal--3419 [005] .... 11152.454887: sys_write(fd: 4, buf: 7ffe4f3a61c0, count: 8)
gnome-terminal--3419 [005] .... 11152.454894: sys_write(fd: 4, buf: 7ffe4f3a61c0, count: 8)
gmain-3193 [002] .... 11152.456141: sys_write(fd: 4, buf: 7fbfe5a93c40, count: 8)
gmain-3193 [002] .... 11152.456168: sys_write(fd: 4, buf: 7fbfe5a92bd0, count: 8)
gmain-3193 [002] .... 11152.456172: sys_write(fd: 4, buf: 7fbfe5a93c40, count: 8)
a.sh-18135 [004] .... 11152.456534: sys_write(fd: 2, buf: 5558769acbd8, count: 2)
a.sh-18135 [004] .... 11152.456547: sys_write(fd: 2, buf: 555877f6a968, count: 6)
a.sh-18135 [004] .... 11152.456555: sys_write(fd: 2, buf: 555877f6a968, count: 2)
a.sh-18135 [004] .... 11152.456561: sys_write(fd: 2, buf: 7ffc5f3f2be7, count: 1)
a.sh-18135 [004] .... 11152.456578: sys_write(fd: 1, buf: 555877f6af00, count: 1)
gnome-terminal--3419 [005] .... 11152.456651: sys_write(fd: 4, buf: 7ffe4f3a61c0, count: 8)
gnome-terminal--3419 [005] .... 11152.456660: sys_write(fd: 4, buf: 7ffe4f3a61c0, count: 8)
a.sh-18135 [004] .... 11152.456674: sys_write(fd: 2, buf: 5558769acbd8, count: 2)
a.sh-18135 [004] .... 11152.456683: sys_write(fd: 2, buf: 555877f6a968, count: 6)
a.sh-18135 [004] .... 11152.456690: sys_write(fd: 2, buf: 555877f6a968, count: 2)
a.sh-18135 [004] .... 11152.456694: sys_write(fd: 2, buf: 7ffc5f3f2be7, count: 1)
a.sh-18135 [004] .... 11152.456703: sys_write(fd: 1, buf: 555877f6af00, count: 1)
a.sh-18135 [004] .... 11152.456738: sys_write(fd: 2, buf: 5558769acb88, count: 2)
a.sh-18135 [004] .... 11152.456745: sys_write(fd: 2, buf: 555877f6a968, count: 3)
a.sh-18135 [004] .... 11152.456750: sys_write(fd: 2, buf: 555877f6a968, count: 14)
a.sh-18135 [004] .... 11152.456756: sys_write(fd: 2, buf: 7ffc5f3f2be7, count: 1)
gnome-terminal--3419 [005] .... 11152.456816: sys_write(fd: 4, buf: 7ffe4f3a61c0, count: 8)
gnome-terminal--3419 [005] .... 11152.456845: sys_write(fd: 4, buf: 7ffe4f3a61c0, count: 8)
如您所见,write
是一个非常常见的系统调用,因此很难隔离我们的两个写调用。通过不太常见的呼叫可以更容易地看到事情,例如: mkdir
:How do I trace a system call in Linux?
测试了Ubuntu 18.04,Linux内核4.15。