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
defer_output 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 <[email protected]>
---
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 244b3e44d090d413..f5652d00b457d096 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
}
}
+ 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;
@@ -1511,6 +1519,7 @@ void evsel__config(struct evsel *evsel, struct
record_opts *opts,
attr->mmap2 = track && !perf_missing_features.mmap2;
attr->comm = track;
attr->build_id = track && opts->build_id;
+ attr->defer_output = track;
/*
* ksymbol is tracked separately with text poke because it needs to be
@@ -2199,6 +2208,10 @@ 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)
+ evsel->core.attr.defer_callchain = 0;
+ if (perf_missing_features.defer_callchain &&
evsel->core.attr.defer_output)
+ evsel->core.attr.defer_output = 0;
if (perf_missing_features.inherit_sample_read &&
evsel->core.attr.inherit &&
(evsel->core.attr.sample_type & PERF_SAMPLE_READ))
evsel->core.attr.inherit = 0;
@@ -2473,6 +2486,13 @@ static bool evsel__detect_missing_features(struct evsel
*evsel, struct perf_cpu
/* Please add new feature detection here. */
+ attr.defer_callchain = true;
+ if (has_attr_feature(&attr, /*flags=*/0))
+ goto found;
+ perf_missing_features.defer_callchain = true;
+ pr_debug2("switching off deferred callchain support\n");
+ attr.defer_callchain = false;
+
attr.inherit = true;
attr.sample_type = PERF_SAMPLE_READ | PERF_SAMPLE_TID;
if (has_attr_feature(&attr, /*flags=*/0))
@@ -2584,6 +2604,10 @@ static bool evsel__detect_missing_features(struct evsel
*evsel, struct perf_cpu
errno = old_errno;
check:
+ if ((evsel->core.attr.defer_callchain || evsel->core.attr.defer_output)
&&
+ 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 3ae4ac8f9a37e009..a08130ff2e47a887 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;
};
extern struct perf_missing_features perf_missing_features;
--
2.52.0.rc1.455.g30608eb744-goog
