Re: will Sysprof work on ARM?

[sandmann cs au dk (Søren Sandmann)]

Adam Dingle <adam yorba org> writes:

> I just built Sysprof 1.1.8 on a Linux system with an ARM processor,
> specifically an NVIDIA Tegra 2 which includes a dual-core ARM
> Cortex-A9.  I ran "sudo sysprof-cli" and the system hung.  Questions:
>
> 1. Is Sysprof expected to work on a system with this CPU?

> 2. If the answer to (1) is yes, then something else must be wrong.  If
> I wanted to debug this, how might I begin?

So far, I haven't heart of anyone successfully using sysprof on ARM, but
it's a very frequent request.

Given that it locks up the system, this is very likely a bug in the perf
counter subsystem in the kernel. It's worth seeing if 

        "perf record -a"

works and if it does, if

        "perf record -a -g"

works. If they also lock up, then reporting the bug to the maintainers
fo the perf system, and the ARM maintainer in particular, would be
worthwhile. If they work, then you would have to figure out how sysprof
is using that system call differently from perf.

To debug it involves rebuilding the kernel inserting print statements in
the perf_counter_open system call code to see where it goes
wrong. Before doing that, it's worth finding out whether the Tegra chip
supports performance counters at all.


Soren