Profiling Kernel function blocks

[Mark Wielaard]

On Thu, 2012-08-02 at 16:17 +0200, Domenico Di Leo wrote:
> I was wondering if anybody has experienced a
> hang of the entire OS when profiling
> the functions of the kernel module.
> In other words, when I run the following script
> probe kernel.function("*@kernel/*.c").return{
>      printf("%s  %s", threadindent(-1),probefunc());
> }
> the entire OS gets stuck.
> I also tried with
> probe kernel.function("*@kernel/*sched.c").return{
>      printf("%s  %s", threadindent(-1),probefunc());
> }
> and after some printing the OS gets stuck again.

This sounds like:
Bug 2725 - function("*") probes sometimes crash & burn
http://sourceware.org/bugzilla/show_bug.cgi?id=2725

> I'm using systemtap v1.4 and kernel 2.6.24 on Gentoo.

Those are pretty old. You might want to try systemtap 1.8.

Cheers,

Mark