linux-kernel - Re: [PATCH v6 3/6] perf record: Add --call-graph fp,defer option for deferred callchains

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Message-ID: <aSS_wR973EKsdW-B@google.com>
Date: Mon, 24 Nov 2025 12:27:45 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Thomas Richter <tmricht@...ux.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	James Clark <james.clark@...aro.org>, Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
	linux-perf-users@...r.kernel.org,
	Steven Rostedt <rostedt@...dmis.org>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Indu Bhagat <indu.bhagat@...cle.com>,
	Jens Remus <jremus@...ux.ibm.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	linux-trace-kernel@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH v6 3/6] perf record: Add --call-graph fp,defer option for
 deferred callchains

Hello,

On Fri, Nov 21, 2025 at 07:26:34AM +0100, Thomas Richter wrote:
> On 11/21/25 00:48, Namhyung Kim wrote:
> > Add a new callchain record mode option for deferred callchains.  For now
> > it only works with FP (frame-pointer) mode.
> > 
> > And add the missing feature detection logic to clear the flag on old
> > kernels.
> > 
> >   $ perf record --call-graph fp,defer -vv true
> 
> Does this also works for dwarf format?
>     # perf record --call-graph dwarf,defer ....

No, it's not supported.  Maybe we can do similar just to dump stack
content and registers for dwarf before returning to user.

Thanks,
Namhyung