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Message-ID: <20240917222820.197594-4-namhyung@kernel.org>
Date: Tue, 17 Sep 2024 15:28:18 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Kan Liang <kan.liang@...ux.intel.com>
Cc: 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,
Josh Poimboeuf <jpoimboe@...nel.org>,
Steven Rostedt <rostedt@...dmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Indu Bhagat <indu.bhagat@...cle.com>,
linux-toolchains@...r.kernel.org
Subject: [PATCH 3/5] perf record: Enable defer_callchain for user callchains
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 <namhyung@...nel.org>
---
tools/perf/util/evsel.c | 17 ++++++++++++++++-
tools/perf/util/evsel.h | 1 +
2 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 701092d6b1b64124..ad89644b32f23035 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -912,6 +912,14 @@ static void __evsel__config_callchain(struct evsel *evsel, struct record_opts *o
}
}
+ if (param->record_mode == CALLCHAIN_FP && !attr->exclude_callchain_user) {
+ /*
+ * Enable deferred callchains optimistically. It'll be switched
+ * off later if the kernel doesn't support it.
+ */
+ attr->defer_callchain = 1;
+ }
+
if (function) {
pr_info("Disabling user space callchains for function trace event.\n");
attr->exclude_callchain_user = 1;
@@ -2089,6 +2097,8 @@ static int __evsel__prepare_open(struct evsel *evsel, struct perf_cpu_map *cpus,
static void evsel__disable_missing_features(struct evsel *evsel)
{
+ if (perf_missing_features.defer_callchain)
+ evsel->core.attr.defer_callchain = 0;
if (perf_missing_features.branch_counters)
evsel->core.attr.branch_sample_type &= ~PERF_SAMPLE_BRANCH_COUNTERS;
if (perf_missing_features.read_lost)
@@ -2144,7 +2154,12 @@ bool evsel__detect_missing_features(struct evsel *evsel)
* Must probe features in the order they were added to the
* perf_event_attr interface.
*/
- if (!perf_missing_features.branch_counters &&
+ if (!perf_missing_features.defer_callchain &&
+ evsel->core.attr.defer_callchain) {
+ perf_missing_features.defer_callchain = true;
+ pr_debug2("switching off deferred callchain support\n");
+ return true;
+ } else if (!perf_missing_features.branch_counters &&
(evsel->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_COUNTERS)) {
perf_missing_features.branch_counters = true;
pr_debug2("switching off branch counters support\n");
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 15e745a9a798fa29..f0a1e1d789420a94 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -221,6 +221,7 @@ struct perf_missing_features {
bool weight_struct;
bool read_lost;
bool branch_counters;
+ bool defer_callchain;
};
extern struct perf_missing_features perf_missing_features;
--
2.46.0.792.g87dc391469-goog
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