Status of rpi work

[Vince Weaver]

On Wed, 13 May 2015, Eric Anholt wrote:

> Vince Weaver <vincent.weaver at maine.edu> writes:
> >
> > Just curious, by "working perf support" do you mean perf_event support for 
> > the ARM processor, or is there going to be perf_event support for the GPU?
> > Or something else entirely?
> 
> I've been failing to get callgraphs in sysprof.  It's hard to do good
> CPU-side optimization work without it.  (-fomit-frame-pointer is
> apparently not the default, so it's not even that that would be the
> problem).

Is this on the Pi or Pi2?  From what I understand on the original Pi the 
perf overflow interrupt is not physically wired up, so any perf work that 
depends on traditional sampling won't work.  There are ways to work around 
that but I am not sure what sysprof is doing internally.

The ARMv7 chip in the Pi2 has a much better performance monitoring unit 
and the overflow is hooked up properly, but I don't think support for that 
has hit upstream yet.

Vince