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 <[email protected]>
Acked-by: Adrian Hunter <[email protected]>
---
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
Hello,
On 2023/8/25 13:10, Ian Rogers wrote:
> On Sun, Aug 20, 2023 at 6:30 PM Yang Jihong <[email protected]> wrote:
>>
>> 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.
>
> I have a hard time understanding this commit message. Let me have a go:
>
> In order to set cpu maps correctly on dummy events they need to set up
> later. Factor out the dummy event initialization from record__open and
> move it to its own function record__setup_dummy_event. Move the call
> to the record__setup_dummy to before the call to
> record__init_thread_masks in cmd_record.
Yes, as you said above, for that purpose
>
>> 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 <[email protected]>
>> Acked-by: Adrian Hunter <[email protected]>
>> ---
>> 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
>
> This code is explicitly talking about dummy events but the function is
> now renamed to call it a tracking event. I think the code should be
> consistent.
>
>> + * 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
>
> Dummy again.
>
This comment directly copies the original content.
I can change to "tracking event" in the next version.
Thanks,
Yang