Re: sysprof in 2.6.27 kernel

[Soeren Sandmann <sandmann@daimi.au.dk>]

Soeren Sandmann <sandmann@daimi.au.dk> writes:

> Lukas Hejtmanek <xhejtman@ics.muni.cz> writes:
> 
> > On Thu, Aug 14, 2008 at 01:23:16AM +0200, Soeren Sandmann wrote:
> > > It's somewhat rough still. If you try it out, I will be interested in
> > > any feedback you have.
> > 
> > another feedback. I got No map at all processes even at those I got debug info
> > installed.
> 
> This may be because sysprof user space is not running as root, or it
> may be because the kernel is generating bogus addresses. 
> 
> Generally, "No Map" means sysprof is seeing samples in memory regions
> that are not in /proc/<pid>/maps

Actually, I seem to remember one cause of this: the vdso code creates
an unusual stackframe where the pointer to the previous frame is
stored in an unusual place. I think the sysprof kernel code needs to
take this into account, or alternatively send sufficient information
to userspace that it can figure it out itself.


Soren