From nobody Fri Oct 3 20:57:37 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9E1F730DEB7; Mon, 25 Aug 2025 18:07:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756145268; cv=none; b=YyCUsyQdlCH+tlgXAtV8eUmkQwX0qjPqx45wZzCrgd6AXjKKjgok1NKXCzF7E7MVtnxfLhbDUp1UbQkrukVtsRpOJO9nTNEIkFI3FWJNGL9oMwCqlitHwrjbL8erNvbojnwAOxDqXbpuZcfg6/lu3ceLtFxpqgju6y5f+1taML0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756145268; c=relaxed/simple; bh=yjVRm7qoaDEwxBX+tn5L8eAZpS2gap8hvaYEm/BHnlI=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=en2usivSHRUtkUQtoYjQAdiSs6l/RoqdfM5vHMRIvmAQenGQdyIgVxRSwxgYzeLgBA29jRhUXUSdpZ8eWgCjF6ynAyl6Utf4nNuXmqMC5kiH8vB/yBM7g/dQv5A04ZEAzHWRYRxXiNpELDfozn0OK/H0qdXOXdhG2qaBPLtSUM4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=uOhsZXFd; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="uOhsZXFd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5096FC19422; Mon, 25 Aug 2025 18:07:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756145268; bh=yjVRm7qoaDEwxBX+tn5L8eAZpS2gap8hvaYEm/BHnlI=; h=Date:From:To:Cc:Subject:References:From; b=uOhsZXFdxWB4eF83D3wFN0Iy8xyh1H485tG4hMxDbTk3bAgQyRXQo29/C8w3sMzzE kut6cZcw7d1DzbPS+ZJUiWSGJn4zZtm+KkwBXd5wmSvvxCk5GfUToTYva5vThZgqxq qDZxSpEfozeyDCKbBVsuKjI51R7/yVK431FYBpbsLGvvCHG8Bc9+rBX96kr5dJy2kD PAKqba9tYy9UA+LttOtfWstA+RERsXndr8TjiXuAP5z3YuRH7TV+gsqmj8athYBP6g F/LIE4FZotVNsfz8xGey+zA0gasQWB0puT3ocUKh7H7itwc77yQdA8xHAzcgzU0AmB NNa7MU7QVWbeA== Received: from rostedt by gandalf with local (Exim 4.98.2) (envelope-from ) id 1uqbbu-00000002n5a-2FdQ; Mon, 25 Aug 2025 14:08:02 -0400 Message-ID: <20250825180802.393100025@kernel.org> User-Agent: quilt/0.68 Date: Mon, 25 Aug 2025 14:06:44 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, x86@kernel.org Cc: Masami Hiramatsu , Mathieu Desnoyers , Josh Poimboeuf , Peter Zijlstra , Ingo Molnar , Jiri Olsa , Arnaldo Carvalho de Melo , Namhyung Kim , Thomas Gleixner , Andrii Nakryiko , Indu Bhagat , "Jose E. Marchesi" , Beau Belgrave , Jens Remus , Linus Torvalds , Andrew Morton , Jens Axboe , Florian Weimer , Sam James Subject: [PATCH v15 6/8] perf record: Enable defer_callchain for user callchains References: <20250825180638.877627656@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Namhyung Kim And add the missing feature detection logic to clear the flag on old kernels. $ perf record -g -vv true ... ------------------------------------------------------------ perf_event_attr: type 0 (PERF_TYPE_HARDWARE) size 136 config 0 (PERF_COUNT_HW_CPU_CYCLES) { sample_period, sample_freq } 4000 sample_type IP|TID|TIME|CALLCHAIN|PERIOD read_format ID|LOST disabled 1 inherit 1 mmap 1 comm 1 freq 1 enable_on_exec 1 task 1 sample_id_all 1 mmap2 1 comm_exec 1 ksymbol 1 bpf_event 1 defer_callchain 1 ------------------------------------------------------------ sys_perf_event_open: pid 162755 cpu 0 group_fd -1 flags 0x8 sys_perf_event_open failed, error -22 switching off deferred callchain support Signed-off-by: Namhyung Kim Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) --- tools/perf/util/evsel.c | 24 ++++++++++++++++++++++++ tools/perf/util/evsel.h | 1 + 2 files changed, 25 insertions(+) diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 7512b9fb877d..438343dbb1c9 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -1061,6 +1061,14 @@ static void __evsel__config_callchain(struct evsel *= evsel, struct record_opts *o } } =20 + if (param->record_mode =3D=3D CALLCHAIN_FP && !attr->exclude_callchain_us= er) { + /* + * Enable deferred callchains optimistically. It'll be switched + * off later if the kernel doesn't support it. + */ + attr->defer_callchain =3D 1; + } + if (function) { pr_info("Disabling user space callchains for function trace event.\n"); attr->exclude_callchain_user =3D 1; @@ -2121,6 +2129,8 @@ static int __evsel__prepare_open(struct evsel *evsel,= struct perf_cpu_map *cpus, =20 static void evsel__disable_missing_features(struct evsel *evsel) { + if (perf_missing_features.defer_callchain) + evsel->core.attr.defer_callchain =3D 0; if (perf_missing_features.inherit_sample_read && evsel->core.attr.inherit= && (evsel->core.attr.sample_type & PERF_SAMPLE_READ)) evsel->core.attr.inherit =3D 0; @@ -2395,6 +2405,15 @@ static bool evsel__detect_missing_features(struct ev= sel *evsel, struct perf_cpu =20 /* Please add new feature detection here. */ =20 + attr.defer_callchain =3D true; + attr.sample_type =3D PERF_SAMPLE_CALLCHAIN; + if (has_attr_feature(&attr, /*flags=3D*/0)) + goto found; + perf_missing_features.defer_callchain =3D true; + pr_debug2("switching off deferred callchain support\n"); + attr.defer_callchain =3D false; + attr.sample_type =3D 0; + attr.inherit =3D true; attr.sample_type =3D PERF_SAMPLE_READ; if (has_attr_feature(&attr, /*flags=3D*/0)) @@ -2506,6 +2525,11 @@ static bool evsel__detect_missing_features(struct ev= sel *evsel, struct perf_cpu errno =3D old_errno; =20 check: + if (evsel->core.attr.defer_callchain && + evsel->core.attr.sample_type & PERF_SAMPLE_CALLCHAIN && + perf_missing_features.defer_callchain) + return true; + if (evsel->core.attr.inherit && (evsel->core.attr.sample_type & PERF_SAMPLE_READ) && perf_missing_features.inherit_sample_read) diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h index 5797a02e5d6a..d9559d29e345 100644 --- a/tools/perf/util/evsel.h +++ b/tools/perf/util/evsel.h @@ -221,6 +221,7 @@ struct perf_missing_features { bool branch_counters; bool aux_action; bool inherit_sample_read; + bool defer_callchain; }; =20 extern struct perf_missing_features perf_missing_features; --=20 2.50.1