Re: [PATCH v5 3/7] perf record: Move setting dummy tracking before record__init_thread_masks()

[Adrian Hunter <adrian.hunter@intel.com>]

On 4/08/23 05:07, Yang Jihong wrote:
> When dummy tracking go system wide, the mmap cpu mask is changed.
> 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@huawei.com>

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
>  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");