lkml.org 
[lkml]   [2015]   [Jan]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: perf not capturing stack traces
Em Mon, Jan 26, 2015 at 10:27:11AM +0000, Will Deacon escreveu:
> On Sun, Jan 25, 2015 at 03:56:52PM +0000, Russell King - ARM Linux wrote:
> > On Sat, Jan 24, 2015 at 04:23:42PM -0600, Felipe Balbi wrote:
> > > yeah, I'll try a few older kernels, also see if I can reproduce on other
> > > boards.
> >
> > Perf works for me with CONFIG_FRAME_POINTER=y, but that's only for kernel
> > space, and for userspace where the programs have been built for ARM mode
> > with frame pointers.
> >
> > The kernel may work without CONFIG_FRAME_POINTER set, but I've never
> > tested that, and I'd suggest that (given my experience looking at oops
> > dumps) it's not all that reliable.
> >
> > Lastly, userspace without frame pointers is pretty much hopeless.
>
> FWIW, perf can now use libunwind for unwinding the userspace side of
> things, so it's not quite as bad as it used to be. For the kernel side,
> if the unwinder isn't working properly it would be nice to know *why*,
> but I agree that it tends to be far flakier than the frame-pointer method.

Any idea why, with userspace using frame pointers, perf doesn't go all
the way from kernel to userspace main() (or whatever is the endpoint),
as Russel stated?

- Arnaldo


\
 
 \ /
  Last update: 2015-01-26 13:21    [W:0.067 / U:1.912 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site