Re: [PATCH v13 00/18] unwind_deferred: Implement sframe handling

Jens Remus
2026-02-09T17:08:47Z

On 2/5/2026 7:54 PM, Steven Rostedt wrote:
> On Thu, 5 Feb 2026 10:26:10 -0800
> Namhyung Kim <namhyung@kernel.org> wrote:
>
>>> Namhyung Kim's related perf tools deferred callchain support can be used
>>> for testing ("perf record --call-graph fp,defer" and "perf report/script").
>>
>> Is it possible for users to choose the unwinder - frame pointer or
>> SFrame at runtime? I feel like the option should be
>> "--call-graph sframe,defer" or just "--call-graph sframe" if it always
>> uses deferred unwinding.
>
> Currently no, and I'm not sure we want that do we? The idea is to use the
> best option that is available. Why use frame pointers if sframe is
> available and it's being called with defer?
>
> If there's no defer, then sframes are not available, so it defaults to the
> best option available (which will likely be frame pointers).

Maybe it would make sense not to "overload" the perf record option
"--call-graph fp,defer" and use it for all deferred unwinding methods.

What about "--call-graph defer", "--call-graph any,defer", or
"--call-graph *,defer"?

Regards,
Jens
--
Jens Remus
Linux on Z Development (D3303)
jremus@de.ibm.com / jremus@linux.ibm.com

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