Re: [PATCH 3/3] tracing: add latency format to function_graphtracer

From: Matt Fleming
Date: Sat Sep 12 2009 - 06:30:31 EST


On Fri, Sep 11, 2009 at 07:08:00PM +0300, Török Edwin wrote:
>
> BTW any plans on integrating an in-kernel unwinder like systemtap has?
>
> Even if I build libc with framepointers, a userspace stacktrace on
> x86-64 can't go beyond most pthreads routines, like __read_nocancel
> (they're written in asm maybe?).
>

fyi SH has an in-kernel DWARF unwinder. It was my intention to shake out
most of the bugs (of which there have been a few) by having it in the SH
tree and then submit it for generic inclusion.

So by carefully placing .cfi_* directives in assembly, you can get
stacktraces for assembly routines in the kernel.

The branch containing the latest code is here,
http://git.kernel.org/?p=linux/kernel/git/lethal/sh-2.6.git;a=shortlog;h=sh/dwarf-unwinder
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