Re: [PATCH 4/5] perf tools: Add evlist__add_sched_switch()

[Adrian Hunter]

On 24/09/22 19:57, Namhyung Kim wrote:
> Add a help to create a system-wide sched_switch event.  One merit is
> that it sets the system-wide bit before adding it to evlist so that
> the libperf can handle the cpu and thread maps correctly.
> 
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>

Reviewed-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>

> ---
>  tools/perf/arch/x86/util/intel-pt.c | 15 +++++----------
>  tools/perf/tests/switch-tracking.c  | 15 +++++----------
>  tools/perf/util/evlist.c            | 17 +++++++++++++++++
>  tools/perf/util/evlist.h            |  1 +
>  4 files changed, 28 insertions(+), 20 deletions(-)
> 
> diff --git a/tools/perf/arch/x86/util/intel-pt.c b/tools/perf/arch/x86/util/intel-pt.c
> index 13933020a79e..793b35f2221a 100644
> --- a/tools/perf/arch/x86/util/intel-pt.c
> +++ b/tools/perf/arch/x86/util/intel-pt.c
> @@ -11,6 +11,7 @@
>  #include <linux/bitops.h>
>  #include <linux/log2.h>
>  #include <linux/zalloc.h>
> +#include <linux/err.h>
>  #include <cpuid.h>
>  
>  #include "../../../util/session.h"
> @@ -426,20 +427,14 @@ static int intel_pt_track_switches(struct evlist *evlist)
>  	if (!evlist__can_select_event(evlist, sched_switch))
>  		return -EPERM;
>  
> -	err = parse_event(evlist, sched_switch);
> -	if (err) {
> -		pr_debug2("%s: failed to parse %s, error %d\n",
> +	evsel = evlist__add_sched_switch(evlist, true);
> +	if (IS_ERR(evsel)) {
> +		err = PTR_ERR(evsel);
> +		pr_debug2("%s: failed to create %s, error = %d\n",
>  			  __func__, sched_switch, err);
>  		return err;
>  	}
>  
> -	evsel = evlist__last(evlist);
> -
> -	evsel__set_sample_bit(evsel, CPU);
> -	evsel__set_sample_bit(evsel, TIME);
> -
> -	evsel->core.system_wide = true;
> -	evsel->no_aux_samples = true;
>  	evsel->immediate = true;
>  
>  	return 0;
> diff --git a/tools/perf/tests/switch-tracking.c b/tools/perf/tests/switch-tracking.c
> index 2d46af9ef935..87f565c7f650 100644
> --- a/tools/perf/tests/switch-tracking.c
> +++ b/tools/perf/tests/switch-tracking.c
> @@ -6,6 +6,7 @@
>  #include <time.h>
>  #include <stdlib.h>
>  #include <linux/zalloc.h>
> +#include <linux/err.h>
>  #include <perf/cpumap.h>
>  #include <perf/evlist.h>
>  #include <perf/mmap.h>
> @@ -398,19 +399,13 @@ static int test__switch_tracking(struct test_suite *test __maybe_unused, int sub
>  		goto out;
>  	}
>  
> -	err = parse_event(evlist, sched_switch);
> -	if (err) {
> -		pr_debug("Failed to parse event %s\n", sched_switch);
> +	switch_evsel = evlist__add_sched_switch(evlist, true);
> +	if (IS_ERR(switch_evsel)) {
> +		err = PTR_ERR(switch_evsel);
> +		pr_debug("Failed to create event %s\n", sched_switch);
>  		goto out_err;
>  	}
>  
> -	switch_evsel = evlist__last(evlist);
> -
> -	evsel__set_sample_bit(switch_evsel, CPU);
> -	evsel__set_sample_bit(switch_evsel, TIME);
> -
> -	switch_evsel->core.system_wide = true;
> -	switch_evsel->no_aux_samples = true;
>  	switch_evsel->immediate = true;
>  
>  	/* Test moving an event to the front */
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index dcf57b271ff1..6612b00949e7 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -288,6 +288,23 @@ struct evsel *evlist__add_aux_dummy(struct evlist *evlist, bool system_wide)
>  	return evsel;
>  }
>  
> +struct evsel *evlist__add_sched_switch(struct evlist *evlist, bool system_wide)
> +{
> +	struct evsel *evsel = evsel__newtp_idx("sched", "sched_switch", 0);
> +
> +	if (IS_ERR(evsel))
> +		return evsel;
> +
> +	evsel__set_sample_bit(evsel, CPU);
> +	evsel__set_sample_bit(evsel, TIME);
> +
> +	evsel->core.system_wide = system_wide;
> +	evsel->no_aux_samples = true;
> +
> +	evlist__add(evlist, evsel);
> +	return evsel;
> +};
> +
>  int evlist__add_attrs(struct evlist *evlist, struct perf_event_attr *attrs, size_t nr_attrs)
>  {
>  	struct evsel *evsel, *n;
> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
> index 9d967fe3953a..16734c6756b3 100644
> --- a/tools/perf/util/evlist.h
> +++ b/tools/perf/util/evlist.h
> @@ -127,6 +127,7 @@ static inline struct evsel *evlist__add_dummy_on_all_cpus(struct evlist *evlist)
>  {
>  	return evlist__add_aux_dummy(evlist, true);
>  }
> +struct evsel *evlist__add_sched_switch(struct evlist *evlist, bool system_wide);
>  
>  int evlist__add_sb_event(struct evlist *evlist, struct perf_event_attr *attr,
>  			 evsel__sb_cb_t cb, void *data);