Re: Linux Kernel GDB tracepoint module 2010-8-30 release

Frank Ch. Eigler
2010-09-03T14:06:09Z

Steven <mqyoung@gmail.com> writes:

> [...]
> (gdb) trace vfs_readdir
> Tracepoint 3 at 0xc1175690: file fs/readdir.c, line 23.
> (gdb) actions
> Enter actions for tracepoint 3, one per line.
> End with a line saying just "end".
> > collect jiffies_64
> > collect *file
> > end

By the way, the systemtap equivalent would be:

#! /usr/bin/stap -g
probe kernel.function("vfs_readdir") {
println(%{ jiffies_64 %})
println($file$)
}

> 2) I can not collect local variable, despite I rebuild the kernel with
> -O0 optimization option. what is the problem? Many thanks
> -------------------------------------------------------------------
> (gdb) trace fs/readdir.c:29
> Tracepoint 2 at 0xc11756ca: file fs/readdir.c, line 29.
> (gdb) actions
> Enter actions for tracepoint 2, one per line.
> End with a line saying just "end".
> > collect res
> > end

#! /usr/bin/stap
probe kernel.statement("*@fs/readdir.c:29") {
println($res)
}

- FChE