Linux Kernel GDB tracepoint module 2010-8-30 release

Frank Ch. Eigler fche@redhat.com
Fri Sep 3 14:06:00 GMT 2010


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



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