Re: [PATCH v5 3/7] perf record: Move setting dummy tracking before record__init_thread_masks()
From: Ian Rogers
Date: Mon Aug 14 2023 - 16:29:55 EST
On Thu, Aug 3, 2023 at 11:58 PM Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
>
> On 4/08/23 05:07, Yang Jihong wrote:
> > When dummy tracking go system wide, the mmap cpu mask is changed.
As previously commented, can we improve the quality of the function
names and commit messages? This sentence is particularly difficult to
understand, I don't understand it.
Thanks,
Ian
> > Therefore, needs to be placed 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 ca83599cc50c..3ff9d972225e 100644
> > --- a/tools/perf/builtin-record.c
> > +++ b/tools/perf/builtin-record.c
> > @@ -908,6 +908,37 @@ 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];
> > @@ -1288,28 +1319,6 @@ 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) {
> > @@ -4235,6 +4244,12 @@ 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");
>