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From: Ingo Molnar on 3 Mar 2010 22:00

* David Miller <davem(a)davemloft.net> wrote:

> And more generally aren't we supposed to be able to eventually analyze perf
> dumps on any platform not just the one 'perf' was built under?

A aidenote: in this cycle Arnaldo improved this aspect of perf (and those
changes are now upstream). In theory you should be able to do a 'perf record'
+ 'perf archive' on your Sparc box and then analyze it via 'perf report' on an
x86 box - and vice versa.

( Note, it was not tested in that specific combination - another combination
was tested by Arnaldo: 32-bit PA-RISC profile interpreted on 64-bit x86. )

So yes, i agree that at minimum perf should be able to tell apart the nature
of any recording and flag combinations it cannot handle (yet).

Btw, i think the most popular use of PEBS is its precise nature, not the
register dumping aspect per se. If the kernel can provide that transparently
then that's a usecase that does not need a register dump (in user-space that
is). It's borderline doable on x86 ...

Thanks,

Ingo
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From: Arnaldo Carvalho de Melo on 4 Mar 2010 08:00
Em Thu, Mar 04, 2010 at 03:59:08AM +0100, Ingo Molnar escreveu:
>
> * David Miller <davem(a)davemloft.net> wrote:
>
> > And more generally aren't we supposed to be able to eventually analyze perf
> > dumps on any platform not just the one 'perf' was built under?
>
> A aidenote: in this cycle Arnaldo improved this aspect of perf (and those
> changes are now upstream). In theory you should be able to do a 'perf record'
> + 'perf archive' on your Sparc box and then analyze it via 'perf report' on an
> x86 box - and vice versa.
>
> ( Note, it was not tested in that specific combination - another combination
> was tested by Arnaldo: 32-bit PA-RISC profile interpreted on 64-bit x86. )

It was the other way around, 64-bit x86 interpreted on 64-bit PARISC.
Should work in any direction.

Caveats:

perf archive requires build-ids, the kernel has them in distros that
have this support in their toolchain, enabled unconditionally since
about 2.6.24.

If vmlinux is available, it will be used, if not a copy of
/proc/kallsyms is made and as well is keyed by build-id.

I have plans to cope with build-id-less systems, but no code yet.

- Arnaldo
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