[PATCH v6 3/7] perf record: Move setting dummy tracking before record__init_thread_masks()
From: Yang Jihong
Date: Sun Aug 20 2023 - 21:30:39 EST
User space tasks can migrate between CPUs, so when tracing selected CPUs,
sideband for all CPUs is needed. In this case set the cpu map of the evsel
to all online CPUs. This may modify the original cpu map of the evlist.
Therefore, need to check whether the preceding scenario exists before
record__init_thread_masks().
Dummy tracking has been set in record__open(), move it before
record__init_thread_masks() and add a helper for unified processing.
The sys_perf_event_open invoked is as follows:
# perf --debug verbose=3 record -e cpu-clock -D 100 true
<SNIP>
Opening: cpu-clock
------------------------------------------------------------
perf_event_attr:
type 1 (PERF_TYPE_SOFTWARE)
size 136
config 0 (PERF_COUNT_SW_CPU_CLOCK)
{ sample_period, sample_freq } 4000
sample_type IP|TID|TIME|PERIOD|IDENTIFIER
read_format ID|LOST
disabled 1
inherit 1
freq 1
sample_id_all 1
exclude_guest 1
------------------------------------------------------------
sys_perf_event_open: pid 10318 cpu 0 group_fd -1 flags 0x8 = 5
sys_perf_event_open: pid 10318 cpu 1 group_fd -1 flags 0x8 = 6
sys_perf_event_open: pid 10318 cpu 2 group_fd -1 flags 0x8 = 7
sys_perf_event_open: pid 10318 cpu 3 group_fd -1 flags 0x8 = 9
sys_perf_event_open: pid 10318 cpu 4 group_fd -1 flags 0x8 = 10
sys_perf_event_open: pid 10318 cpu 5 group_fd -1 flags 0x8 = 11
sys_perf_event_open: pid 10318 cpu 6 group_fd -1 flags 0x8 = 12
sys_perf_event_open: pid 10318 cpu 7 group_fd -1 flags 0x8 = 13
Opening: dummy:u
------------------------------------------------------------
perf_event_attr:
type 1 (PERF_TYPE_SOFTWARE)
size 136
config 0x9 (PERF_COUNT_SW_DUMMY)
{ sample_period, sample_freq } 1
sample_type IP|TID|TIME|IDENTIFIER
read_format ID|LOST
disabled 1
inherit 1
exclude_kernel 1
exclude_hv 1
mmap 1
comm 1
enable_on_exec 1
task 1
sample_id_all 1
exclude_guest 1
mmap2 1
comm_exec 1
ksymbol 1
bpf_event 1
------------------------------------------------------------
sys_perf_event_open: pid 10318 cpu 0 group_fd -1 flags 0x8 = 14
sys_perf_event_open: pid 10318 cpu 1 group_fd -1 flags 0x8 = 15
sys_perf_event_open: pid 10318 cpu 2 group_fd -1 flags 0x8 = 16
sys_perf_event_open: pid 10318 cpu 3 group_fd -1 flags 0x8 = 17
sys_perf_event_open: pid 10318 cpu 4 group_fd -1 flags 0x8 = 18
sys_perf_event_open: pid 10318 cpu 5 group_fd -1 flags 0x8 = 19
sys_perf_event_open: pid 10318 cpu 6 group_fd -1 flags 0x8 = 20
sys_perf_event_open: pid 10318 cpu 7 group_fd -1 flags 0x8 = 21
<SNIP>
Signed-off-by: Yang Jihong <yangjihong1@xxxxxxxxxx>
Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
tools/perf/builtin-record.c | 59 +++++++++++++++++++++++--------------
1 file changed, 37 insertions(+), 22 deletions(-)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 12edad8392cc..4ee94058028f 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -906,6 +906,37 @@ static int record__config_off_cpu(struct record *rec)
return off_cpu_prepare(rec->evlist, &rec->opts.target, &rec->opts);
}
+static int record__config_tracking_events(struct record *rec)
+{
+ struct record_opts *opts = &rec->opts;
+ struct evlist *evlist = rec->evlist;
+ struct evsel *evsel;
+
+ /*
+ * For initial_delay, system wide or a hybrid system, we need to add a
+ * dummy event so that we can track PERF_RECORD_MMAP to cover the delay
+ * of waiting or event synthesis.
+ */
+ if (opts->target.initial_delay || target__has_cpu(&opts->target) ||
+ perf_pmus__num_core_pmus() > 1) {
+ evsel = evlist__findnew_tracking_event(evlist, false);
+ if (!evsel)
+ return -ENOMEM;
+
+ /*
+ * Enable the dummy event when the process is forked for
+ * initial_delay, immediately for system wide.
+ */
+ if (opts->target.initial_delay && !evsel->immediate &&
+ !target__has_cpu(&opts->target))
+ evsel->core.attr.enable_on_exec = 1;
+ else
+ evsel->immediate = 1;
+ }
+
+ return 0;
+}
+
static bool record__kcore_readable(struct machine *machine)
{
char kcore[PATH_MAX];
@@ -1286,28 +1317,6 @@ static int record__open(struct record *rec)
struct record_opts *opts = &rec->opts;
int rc = 0;
- /*
- * For initial_delay, system wide or a hybrid system, we need to add a
- * dummy event so that we can track PERF_RECORD_MMAP to cover the delay
- * of waiting or event synthesis.
- */
- if (opts->target.initial_delay || target__has_cpu(&opts->target) ||
- perf_pmus__num_core_pmus() > 1) {
- pos = evlist__findnew_tracking_event(evlist, false);
- if (!pos)
- return -ENOMEM;
-
- /*
- * Enable the dummy event when the process is forked for
- * initial_delay, immediately for system wide.
- */
- if (opts->target.initial_delay && !pos->immediate &&
- !target__has_cpu(&opts->target))
- pos->core.attr.enable_on_exec = 1;
- else
- pos->immediate = 1;
- }
-
evlist__config(evlist, opts, &callchain_param);
evlist__for_each_entry(evlist, pos) {
@@ -4190,6 +4199,12 @@ int cmd_record(int argc, const char **argv)
goto out;
}
+ err = record__config_tracking_events(rec);
+ if (err) {
+ pr_err("record__config_tracking_events failed, error %d\n", err);
+ goto out;
+ }
+
err = record__init_thread_masks(rec);
if (err) {
pr_err("Failed to initialize parallel data streaming masks\n");
--
2.30.GIT