[v1,1/9] perf pmu: Add documentation

  Add documentation to struct perf_pmu and the associated structs of
perf_pmu_alias and perf_pmu_format.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/pmu.c |  14 ++++++
 tools/perf/util/pmu.h | 105 +++++++++++++++++++++++++++++++++++++++---
 2 files changed, 113 insertions(+), 6 deletions(-)
  

On 14/11/22 09:51, Ian Rogers wrote:
> Add documentation to struct perf_pmu and the associated structs of
> perf_pmu_alias and perf_pmu_format.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>

Should this be kernel-doc format?

$ ./scripts/kernel-doc -man tools/perf/util/pmu.* > /tmp/manout
tools/perf/util/pmu.c:35: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
 * Values from a format file read from <sysfs>/devices/cpu/format/ held in
tools/perf/util/pmu.c:1: warning: no structured comments found
tools/perf/util/pmu.h:140: warning: cannot understand function prototype: 'struct perf_pmu_alias '
tools/perf/util/pmu.h:1: warning: no structured comments found
tools/perf/util/pmu.l:1: warning: no structured comments found
tools/perf/util/pmu.o:1: warning: no structured comments found
tools/perf/util/pmu.y:1: warning: no structured comments found
$ man -l /tmp/manout | cat
$

> ---
>  tools/perf/util/pmu.c |  14 ++++++
>  tools/perf/util/pmu.h | 105 +++++++++++++++++++++++++++++++++++++++---
>  2 files changed, 113 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 6a86e6af0903..a8f9f47c6ed9 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -31,10 +31,24 @@
>  
>  struct perf_pmu perf_pmu__fake;
>  
> +/**
> + * Values from a format file read from <sysfs>/devices/cpu/format/ held in
> + * struct perf_pmu. For example, the contents of
> + * <sysfs>/devices/cpu/format/event may be "config:0-7" and will be represented
> + * here as name="event", value=PERF_PMU_FORMAT_VALUE_CONFIG and bits 0 to 7 will
> + * be set.
> + */
>  struct perf_pmu_format {
> +	/** The modifier/file name. */
>  	char *name;
> +	/**
> +	 * Which config value the format relates to. Supported values are from
> +	 * PERF_PMU_FORMAT_VALUE_CONFIG to PERF_PMU_FORMAT_VALUE_CONFIG_END.
> +	 */
>  	int value;
> +	/** Which config bits are set by this format value. */
>  	DECLARE_BITMAP(bits, PERF_PMU_FORMAT_BITS);
> +	/** Element on list within struct perf_pmu. */
>  	struct list_head list;
>  };
>  
> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> index 68e15c38ae71..29571c0f9d15 100644
> --- a/tools/perf/util/pmu.h
> +++ b/tools/perf/util/pmu.h
> @@ -34,30 +34,91 @@ struct perf_pmu_caps {
>  };
>  
>  struct perf_pmu {
> +	/** The name of the PMU such as "cpu". */
>  	char *name;
> +	/**
> +	 * Optional alternate name for the PMU determined in architecture
> +	 * specific code.
> +	 */
>  	char *alias_name;
> +	/**
> +	 * Optional PMU identifier read from
> +	 * <sysfs>/bus/event_source/devices/<name>/identifier.
> +	 */
>  	char *id;
> +	/**
> +	 * Perf event attributed type value, read from
> +	 * <sysfs>/bus/event_source/devices/<name>/type.
> +	 */
>  	__u32 type;
> +	/**
> +	 * Can the PMU name be selected as if it were an event?
> +	 */
>  	bool selectable;
> +	/**
> +	 * Is the PMU not within the CPU core? Determined by the presence of
> +	 * <sysfs>/bus/event_source/devices/<name>/cpumask.
> +	 */
>  	bool is_uncore;
> +	/** Is the PMU name either cpu_core or cpu_atom. */
>  	bool is_hybrid;
> +	/**
> +	 * Are events auxiliary events? Determined in architecture specific
> +	 * code.
> +	 */
>  	bool auxtrace;
> +	/**
> +	 * Number of levels of :ppp precision supported by the PMU, read from
> +	 * <sysfs>/bus/event_source/devices/<name>/caps/max_precise.
> +	 */
>  	int max_precise;
> +	/**
> +	 * Optional default perf_event_attr determined in architecture specific
> +	 * code.
> +	 */
>  	struct perf_event_attr *default_config;
> +	/**
> +	 * Empty or the contents of either of:
> +	 * <sysfs>/bus/event_source/devices/<name>/cpumask.
> +	 * <sysfs>/bus/event_source/devices/<cpu>/cpus.
> +	 */
>  	struct perf_cpu_map *cpus;
> -	struct list_head format;  /* HEAD struct perf_pmu_format -> list */
> -	struct list_head aliases; /* HEAD struct perf_pmu_alias -> list */
> +	/**
> +	 * Holds the contents of files read from
> +	 * <sysfs>/bus/event_source/devices/<name>/format/. The contents specify
> +	 * which event parameter changes what config, config1 or config2 bits.
> +	 */
> +	struct list_head format;
> +	/**
> +	 * List of struct perf_pmu_alias. Each alias corresponds to an event
> +	 * read from <sysfs>/bus/event_source/devices/<name>/events/ or from
> +	 * json events in pmu-events.c.
> +	 */
> +	struct list_head aliases;
> +	/** Has the list caps been initialized? */
>  	bool caps_initialized;
> +	/** The length of the list caps. */
>  	u32 nr_caps;
> -	struct list_head caps;    /* HEAD struct perf_pmu_caps -> list */
> -	struct list_head list;    /* ELEM */
> +	/**
> +	 * Holds the contents of files read from
> +	 * <sysfs>/bus/event_source/devices/<name>/caps/. The contents are pairs
> +	 * of the filename with the value of its contents, for example,
> +	 * max_precise (see above) may have a value of 3.
> +	 */
> +	struct list_head caps;
> +	/** Element on pmus list in pmu.c. */
> +	struct list_head list;
> +	/** Element on perf_pmu__hybrid_pmus. */
>  	struct list_head hybrid_list;
>  
> +	/** Features to inhibit when events on this PMU are opened. */
>  	struct {
> +		/** Disables perf_event_attr exclude_guest and exclude_host. */
>  		bool exclude_guest;
>  	} missing_features;
>  };
>  
> +/** A special global PMU used for testing. */
>  extern struct perf_pmu perf_pmu__fake;
>  
>  struct perf_pmu_info {
> @@ -71,21 +132,53 @@ struct perf_pmu_info {
>  
>  #define UNIT_MAX_LEN	31 /* max length for event unit name */
>  
> +/**
> + * An event either read from sysfs or builtin in pmu-events.c, created by
> + * parsing the pmu-events json files.
> + */
>  struct perf_pmu_alias {
>  	char *name;
> +	/** Optional short description of the event. */
>  	char *desc;
> +	/** Optional long description. */
>  	char *long_desc;
> +	/**
> +	 * Optional topic such as cache or pipeline, particularly for json
> +	 * events.
> +	 */
>  	char *topic;
> +	/** Comma separated parameter list. */
>  	char *str;
> -	struct list_head terms; /* HEAD struct parse_events_term -> list */
> -	struct list_head list;  /* ELEM */
> +	/** Owned list of the original parsed parameters. */
> +	struct list_head terms;
> +	/** List element of struct perf_pmu aliases. */
> +	struct list_head list;
> +	/** Units for the event, such as bytes or cache lines. */
>  	char unit[UNIT_MAX_LEN+1];
> +	/** Value to scale read counter values by. */
>  	double scale;
> +	/**
> +	 * Does the file
> +	 * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.per-pkg or
> +	 * equivalent json value exist and have the value 1.
> +	 */
>  	bool per_pkg;
> +	/**
> +	 * Does the file
> +	 * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.snapshot
> +	 * exist and have the value 1.
> +	 */
>  	bool snapshot;
> +	/** Is the event hidden and so not shown in perf list by default. */
>  	bool deprecated;
> +	/**
> +	 * A metric expression associated with an event. Doing this makes little
> +	 * sense due to scale and unit applying to both.
> +	 */
>  	char *metric_expr;
> +	/** A name for the metric. unit applying to both. */
>  	char *metric_name;
> +	/** The name copied from struct perf_pmu. */
>  	char *pmu_name;
>  };
>
  

On 2022-11-14 2:51 a.m., Ian Rogers wrote:
> Add documentation to struct perf_pmu and the associated structs of
> perf_pmu_alias and perf_pmu_format.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/util/pmu.c |  14 ++++++
>  tools/perf/util/pmu.h | 105 +++++++++++++++++++++++++++++++++++++++---
>  2 files changed, 113 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 6a86e6af0903..a8f9f47c6ed9 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -31,10 +31,24 @@
>  
>  struct perf_pmu perf_pmu__fake;
>  
> +/**
> + * Values from a format file read from <sysfs>/devices/cpu/format/ held in
> + * struct perf_pmu. For example, the contents of
> + * <sysfs>/devices/cpu/format/event may be "config:0-7" and will be represented
> + * here as name="event", value=PERF_PMU_FORMAT_VALUE_CONFIG and bits 0 to 7 will
> + * be set.
> + */
>  struct perf_pmu_format {
> +	/** The modifier/file name. */
>  	char *name;
> +	/**
> +	 * Which config value the format relates to. Supported values are from
> +	 * PERF_PMU_FORMAT_VALUE_CONFIG to PERF_PMU_FORMAT_VALUE_CONFIG_END.
> +	 */
>  	int value;
> +	/** Which config bits are set by this format value. */
>  	DECLARE_BITMAP(bits, PERF_PMU_FORMAT_BITS);
> +	/** Element on list within struct perf_pmu. */
>  	struct list_head list;
>  };
>  
> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> index 68e15c38ae71..29571c0f9d15 100644
> --- a/tools/perf/util/pmu.h
> +++ b/tools/perf/util/pmu.h
> @@ -34,30 +34,91 @@ struct perf_pmu_caps {
>  };
>  
>  struct perf_pmu {
> +	/** The name of the PMU such as "cpu". */
>  	char *name;
> +	/**
> +	 * Optional alternate name for the PMU determined in architecture
> +	 * specific code.
> +	 */
>  	char *alias_name;
> +	/**
> +	 * Optional PMU identifier read from
> +	 * <sysfs>/bus/event_source/devices/<name>/identifier.
> +	 */
>  	char *id;
> +	/**
> +	 * Perf event attributed type value, read from
> +	 * <sysfs>/bus/event_source/devices/<name>/type.
> +	 */
>  	__u32 type;
> +	/**
> +	 * Can the PMU name be selected as if it were an event?
> +	 */
>  	bool selectable;
> +	/**
> +	 * Is the PMU not within the CPU core? Determined by the presence of
> +	 * <sysfs>/bus/event_source/devices/<name>/cpumask.
> +	 */
>  	bool is_uncore;
> +	/** Is the PMU name either cpu_core or cpu_atom. */

I don't think we want to limit the hybrid names only to cpu_core or
cpu_atom. Maybe something as below?
/* Is a hybrid CPU PMU, e.g., cpu_core, cpu_atom. */

Thanks,
Kan

>  	bool is_hybrid;
> +	/**
> +	 * Are events auxiliary events? Determined in architecture specific
> +	 * code.
> +	 */
>  	bool auxtrace;
> +	/**
> +	 * Number of levels of :ppp precision supported by the PMU, read from
> +	 * <sysfs>/bus/event_source/devices/<name>/caps/max_precise.
> +	 */
>  	int max_precise;
> +	/**
> +	 * Optional default perf_event_attr determined in architecture specific
> +	 * code.
> +	 */
>  	struct perf_event_attr *default_config;
> +	/**
> +	 * Empty or the contents of either of:
> +	 * <sysfs>/bus/event_source/devices/<name>/cpumask.
> +	 * <sysfs>/bus/event_source/devices/<cpu>/cpus.
> +	 */
>  	struct perf_cpu_map *cpus;
> -	struct list_head format;  /* HEAD struct perf_pmu_format -> list */
> -	struct list_head aliases; /* HEAD struct perf_pmu_alias -> list */
> +	/**
> +	 * Holds the contents of files read from
> +	 * <sysfs>/bus/event_source/devices/<name>/format/. The contents specify
> +	 * which event parameter changes what config, config1 or config2 bits.
> +	 */
> +	struct list_head format;
> +	/**
> +	 * List of struct perf_pmu_alias. Each alias corresponds to an event
> +	 * read from <sysfs>/bus/event_source/devices/<name>/events/ or from
> +	 * json events in pmu-events.c.
> +	 */
> +	struct list_head aliases;
> +	/** Has the list caps been initialized? */
>  	bool caps_initialized;
> +	/** The length of the list caps. */
>  	u32 nr_caps;
> -	struct list_head caps;    /* HEAD struct perf_pmu_caps -> list */
> -	struct list_head list;    /* ELEM */
> +	/**
> +	 * Holds the contents of files read from
> +	 * <sysfs>/bus/event_source/devices/<name>/caps/. The contents are pairs
> +	 * of the filename with the value of its contents, for example,
> +	 * max_precise (see above) may have a value of 3.
> +	 */
> +	struct list_head caps;
> +	/** Element on pmus list in pmu.c. */
> +	struct list_head list;
> +	/** Element on perf_pmu__hybrid_pmus. */
>  	struct list_head hybrid_list;
>  
> +	/** Features to inhibit when events on this PMU are opened. */
>  	struct {
> +		/** Disables perf_event_attr exclude_guest and exclude_host. */
>  		bool exclude_guest;
>  	} missing_features;
>  };
>  
> +/** A special global PMU used for testing. */
>  extern struct perf_pmu perf_pmu__fake;
>  
>  struct perf_pmu_info {
> @@ -71,21 +132,53 @@ struct perf_pmu_info {
>  
>  #define UNIT_MAX_LEN	31 /* max length for event unit name */
>  
> +/**
> + * An event either read from sysfs or builtin in pmu-events.c, created by
> + * parsing the pmu-events json files.
> + */
>  struct perf_pmu_alias {
>  	char *name;
> +	/** Optional short description of the event. */
>  	char *desc;
> +	/** Optional long description. */
>  	char *long_desc;
> +	/**
> +	 * Optional topic such as cache or pipeline, particularly for json
> +	 * events.
> +	 */
>  	char *topic;
> +	/** Comma separated parameter list. */
>  	char *str;
> -	struct list_head terms; /* HEAD struct parse_events_term -> list */
> -	struct list_head list;  /* ELEM */
> +	/** Owned list of the original parsed parameters. */
> +	struct list_head terms;
> +	/** List element of struct perf_pmu aliases. */
> +	struct list_head list;
> +	/** Units for the event, such as bytes or cache lines. */
>  	char unit[UNIT_MAX_LEN+1];
> +	/** Value to scale read counter values by. */
>  	double scale;
> +	/**
> +	 * Does the file
> +	 * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.per-pkg or
> +	 * equivalent json value exist and have the value 1.
> +	 */
>  	bool per_pkg;
> +	/**
> +	 * Does the file
> +	 * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.snapshot
> +	 * exist and have the value 1.
> +	 */
>  	bool snapshot;
> +	/** Is the event hidden and so not shown in perf list by default. */
>  	bool deprecated;
> +	/**
> +	 * A metric expression associated with an event. Doing this makes little
> +	 * sense due to scale and unit applying to both.
> +	 */
>  	char *metric_expr;
> +	/** A name for the metric. unit applying to both. */
>  	char *metric_name;
> +	/** The name copied from struct perf_pmu. */
>  	char *pmu_name;
>  };
>
  

On Mon, Nov 14, 2022 at 5:40 AM Liang, Kan <kan.liang@linux.intel.com> wrote:
>
>
>
> On 2022-11-14 2:51 a.m., Ian Rogers wrote:
> > Add documentation to struct perf_pmu and the associated structs of
> > perf_pmu_alias and perf_pmu_format.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> >  tools/perf/util/pmu.c |  14 ++++++
> >  tools/perf/util/pmu.h | 105 +++++++++++++++++++++++++++++++++++++++---
> >  2 files changed, 113 insertions(+), 6 deletions(-)
> >
> > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> > index 6a86e6af0903..a8f9f47c6ed9 100644
> > --- a/tools/perf/util/pmu.c
> > +++ b/tools/perf/util/pmu.c
> > @@ -31,10 +31,24 @@
> >
> >  struct perf_pmu perf_pmu__fake;
> >
> > +/**
> > + * Values from a format file read from <sysfs>/devices/cpu/format/ held in
> > + * struct perf_pmu. For example, the contents of
> > + * <sysfs>/devices/cpu/format/event may be "config:0-7" and will be represented
> > + * here as name="event", value=PERF_PMU_FORMAT_VALUE_CONFIG and bits 0 to 7 will
> > + * be set.
> > + */
> >  struct perf_pmu_format {
> > +     /** The modifier/file name. */
> >       char *name;
> > +     /**
> > +      * Which config value the format relates to. Supported values are from
> > +      * PERF_PMU_FORMAT_VALUE_CONFIG to PERF_PMU_FORMAT_VALUE_CONFIG_END.
> > +      */
> >       int value;
> > +     /** Which config bits are set by this format value. */
> >       DECLARE_BITMAP(bits, PERF_PMU_FORMAT_BITS);
> > +     /** Element on list within struct perf_pmu. */
> >       struct list_head list;
> >  };
> >
> > diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> > index 68e15c38ae71..29571c0f9d15 100644
> > --- a/tools/perf/util/pmu.h
> > +++ b/tools/perf/util/pmu.h
> > @@ -34,30 +34,91 @@ struct perf_pmu_caps {
> >  };
> >
> >  struct perf_pmu {
> > +     /** The name of the PMU such as "cpu". */
> >       char *name;
> > +     /**
> > +      * Optional alternate name for the PMU determined in architecture
> > +      * specific code.
> > +      */
> >       char *alias_name;
> > +     /**
> > +      * Optional PMU identifier read from
> > +      * <sysfs>/bus/event_source/devices/<name>/identifier.
> > +      */
> >       char *id;
> > +     /**
> > +      * Perf event attributed type value, read from
> > +      * <sysfs>/bus/event_source/devices/<name>/type.
> > +      */
> >       __u32 type;
> > +     /**
> > +      * Can the PMU name be selected as if it were an event?
> > +      */
> >       bool selectable;
> > +     /**
> > +      * Is the PMU not within the CPU core? Determined by the presence of
> > +      * <sysfs>/bus/event_source/devices/<name>/cpumask.
> > +      */
> >       bool is_uncore;
> > +     /** Is the PMU name either cpu_core or cpu_atom. */
>
> I don't think we want to limit the hybrid names only to cpu_core or
> cpu_atom. Maybe something as below?
> /* Is a hybrid CPU PMU, e.g., cpu_core, cpu_atom. */

Currently the hybrid code only works for cpu_core or cpu_atom, a
limitation of its implementation. As pointed out in a later patch,
this bool isn't being used when it could be and I think we can work to
remove it. It would be possible to remove all uses of this with
perf_pmu__is_hybrid. As such I think it may be useful to mark the
hybrid variables in struct perf_pmu as deprecated while we work to
replace their use with more generic just any PMU code.

Thanks,
Ian

> Thanks,
> Kan
>
> >       bool is_hybrid;
> > +     /**
> > +      * Are events auxiliary events? Determined in architecture specific
> > +      * code.
> > +      */
> >       bool auxtrace;
> > +     /**
> > +      * Number of levels of :ppp precision supported by the PMU, read from
> > +      * <sysfs>/bus/event_source/devices/<name>/caps/max_precise.
> > +      */
> >       int max_precise;
> > +     /**
> > +      * Optional default perf_event_attr determined in architecture specific
> > +      * code.
> > +      */
> >       struct perf_event_attr *default_config;
> > +     /**
> > +      * Empty or the contents of either of:
> > +      * <sysfs>/bus/event_source/devices/<name>/cpumask.
> > +      * <sysfs>/bus/event_source/devices/<cpu>/cpus.
> > +      */
> >       struct perf_cpu_map *cpus;
> > -     struct list_head format;  /* HEAD struct perf_pmu_format -> list */
> > -     struct list_head aliases; /* HEAD struct perf_pmu_alias -> list */
> > +     /**
> > +      * Holds the contents of files read from
> > +      * <sysfs>/bus/event_source/devices/<name>/format/. The contents specify
> > +      * which event parameter changes what config, config1 or config2 bits.
> > +      */
> > +     struct list_head format;
> > +     /**
> > +      * List of struct perf_pmu_alias. Each alias corresponds to an event
> > +      * read from <sysfs>/bus/event_source/devices/<name>/events/ or from
> > +      * json events in pmu-events.c.
> > +      */
> > +     struct list_head aliases;
> > +     /** Has the list caps been initialized? */
> >       bool caps_initialized;
> > +     /** The length of the list caps. */
> >       u32 nr_caps;
> > -     struct list_head caps;    /* HEAD struct perf_pmu_caps -> list */
> > -     struct list_head list;    /* ELEM */
> > +     /**
> > +      * Holds the contents of files read from
> > +      * <sysfs>/bus/event_source/devices/<name>/caps/. The contents are pairs
> > +      * of the filename with the value of its contents, for example,
> > +      * max_precise (see above) may have a value of 3.
> > +      */
> > +     struct list_head caps;
> > +     /** Element on pmus list in pmu.c. */
> > +     struct list_head list;
> > +     /** Element on perf_pmu__hybrid_pmus. */
> >       struct list_head hybrid_list;
> >
> > +     /** Features to inhibit when events on this PMU are opened. */
> >       struct {
> > +             /** Disables perf_event_attr exclude_guest and exclude_host. */
> >               bool exclude_guest;
> >       } missing_features;
> >  };
> >
> > +/** A special global PMU used for testing. */
> >  extern struct perf_pmu perf_pmu__fake;
> >
> >  struct perf_pmu_info {
> > @@ -71,21 +132,53 @@ struct perf_pmu_info {
> >
> >  #define UNIT_MAX_LEN 31 /* max length for event unit name */
> >
> > +/**
> > + * An event either read from sysfs or builtin in pmu-events.c, created by
> > + * parsing the pmu-events json files.
> > + */
> >  struct perf_pmu_alias {
> >       char *name;
> > +     /** Optional short description of the event. */
> >       char *desc;
> > +     /** Optional long description. */
> >       char *long_desc;
> > +     /**
> > +      * Optional topic such as cache or pipeline, particularly for json
> > +      * events.
> > +      */
> >       char *topic;
> > +     /** Comma separated parameter list. */
> >       char *str;
> > -     struct list_head terms; /* HEAD struct parse_events_term -> list */
> > -     struct list_head list;  /* ELEM */
> > +     /** Owned list of the original parsed parameters. */
> > +     struct list_head terms;
> > +     /** List element of struct perf_pmu aliases. */
> > +     struct list_head list;
> > +     /** Units for the event, such as bytes or cache lines. */
> >       char unit[UNIT_MAX_LEN+1];
> > +     /** Value to scale read counter values by. */
> >       double scale;
> > +     /**
> > +      * Does the file
> > +      * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.per-pkg or
> > +      * equivalent json value exist and have the value 1.
> > +      */
> >       bool per_pkg;
> > +     /**
> > +      * Does the file
> > +      * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.snapshot
> > +      * exist and have the value 1.
> > +      */
> >       bool snapshot;
> > +     /** Is the event hidden and so not shown in perf list by default. */
> >       bool deprecated;
> > +     /**
> > +      * A metric expression associated with an event. Doing this makes little
> > +      * sense due to scale and unit applying to both.
> > +      */
> >       char *metric_expr;
> > +     /** A name for the metric. unit applying to both. */
> >       char *metric_name;
> > +     /** The name copied from struct perf_pmu. */
> >       char *pmu_name;
> >  };
> >
  

On Mon, Nov 14, 2022 at 12:56 AM Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> On 14/11/22 09:51, Ian Rogers wrote:
> > Add documentation to struct perf_pmu and the associated structs of
> > perf_pmu_alias and perf_pmu_format.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
>
> Should this be kernel-doc format?
>
> $ ./scripts/kernel-doc -man tools/perf/util/pmu.* > /tmp/manout
> tools/perf/util/pmu.c:35: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
>  * Values from a format file read from <sysfs>/devices/cpu/format/ held in
> tools/perf/util/pmu.c:1: warning: no structured comments found
> tools/perf/util/pmu.h:140: warning: cannot understand function prototype: 'struct perf_pmu_alias '
> tools/perf/util/pmu.h:1: warning: no structured comments found
> tools/perf/util/pmu.l:1: warning: no structured comments found
> tools/perf/util/pmu.o:1: warning: no structured comments found
> tools/perf/util/pmu.y:1: warning: no structured comments found
> $ man -l /tmp/manout | cat
> $

Thanks, I'll take a look into fixing this.

Ian

> > ---
> >  tools/perf/util/pmu.c |  14 ++++++
> >  tools/perf/util/pmu.h | 105 +++++++++++++++++++++++++++++++++++++++---
> >  2 files changed, 113 insertions(+), 6 deletions(-)
> >
> > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> > index 6a86e6af0903..a8f9f47c6ed9 100644
> > --- a/tools/perf/util/pmu.c
> > +++ b/tools/perf/util/pmu.c
> > @@ -31,10 +31,24 @@
> >
> >  struct perf_pmu perf_pmu__fake;
> >
> > +/**
> > + * Values from a format file read from <sysfs>/devices/cpu/format/ held in
> > + * struct perf_pmu. For example, the contents of
> > + * <sysfs>/devices/cpu/format/event may be "config:0-7" and will be represented
> > + * here as name="event", value=PERF_PMU_FORMAT_VALUE_CONFIG and bits 0 to 7 will
> > + * be set.
> > + */
> >  struct perf_pmu_format {
> > +     /** The modifier/file name. */
> >       char *name;
> > +     /**
> > +      * Which config value the format relates to. Supported values are from
> > +      * PERF_PMU_FORMAT_VALUE_CONFIG to PERF_PMU_FORMAT_VALUE_CONFIG_END.
> > +      */
> >       int value;
> > +     /** Which config bits are set by this format value. */
> >       DECLARE_BITMAP(bits, PERF_PMU_FORMAT_BITS);
> > +     /** Element on list within struct perf_pmu. */
> >       struct list_head list;
> >  };
> >
> > diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> > index 68e15c38ae71..29571c0f9d15 100644
> > --- a/tools/perf/util/pmu.h
> > +++ b/tools/perf/util/pmu.h
> > @@ -34,30 +34,91 @@ struct perf_pmu_caps {
> >  };
> >
> >  struct perf_pmu {
> > +     /** The name of the PMU such as "cpu". */
> >       char *name;
> > +     /**
> > +      * Optional alternate name for the PMU determined in architecture
> > +      * specific code.
> > +      */
> >       char *alias_name;
> > +     /**
> > +      * Optional PMU identifier read from
> > +      * <sysfs>/bus/event_source/devices/<name>/identifier.
> > +      */
> >       char *id;
> > +     /**
> > +      * Perf event attributed type value, read from
> > +      * <sysfs>/bus/event_source/devices/<name>/type.
> > +      */
> >       __u32 type;
> > +     /**
> > +      * Can the PMU name be selected as if it were an event?
> > +      */
> >       bool selectable;
> > +     /**
> > +      * Is the PMU not within the CPU core? Determined by the presence of
> > +      * <sysfs>/bus/event_source/devices/<name>/cpumask.
> > +      */
> >       bool is_uncore;
> > +     /** Is the PMU name either cpu_core or cpu_atom. */
> >       bool is_hybrid;
> > +     /**
> > +      * Are events auxiliary events? Determined in architecture specific
> > +      * code.
> > +      */
> >       bool auxtrace;
> > +     /**
> > +      * Number of levels of :ppp precision supported by the PMU, read from
> > +      * <sysfs>/bus/event_source/devices/<name>/caps/max_precise.
> > +      */
> >       int max_precise;
> > +     /**
> > +      * Optional default perf_event_attr determined in architecture specific
> > +      * code.
> > +      */
> >       struct perf_event_attr *default_config;
> > +     /**
> > +      * Empty or the contents of either of:
> > +      * <sysfs>/bus/event_source/devices/<name>/cpumask.
> > +      * <sysfs>/bus/event_source/devices/<cpu>/cpus.
> > +      */
> >       struct perf_cpu_map *cpus;
> > -     struct list_head format;  /* HEAD struct perf_pmu_format -> list */
> > -     struct list_head aliases; /* HEAD struct perf_pmu_alias -> list */
> > +     /**
> > +      * Holds the contents of files read from
> > +      * <sysfs>/bus/event_source/devices/<name>/format/. The contents specify
> > +      * which event parameter changes what config, config1 or config2 bits.
> > +      */
> > +     struct list_head format;
> > +     /**
> > +      * List of struct perf_pmu_alias. Each alias corresponds to an event
> > +      * read from <sysfs>/bus/event_source/devices/<name>/events/ or from
> > +      * json events in pmu-events.c.
> > +      */
> > +     struct list_head aliases;
> > +     /** Has the list caps been initialized? */
> >       bool caps_initialized;
> > +     /** The length of the list caps. */
> >       u32 nr_caps;
> > -     struct list_head caps;    /* HEAD struct perf_pmu_caps -> list */
> > -     struct list_head list;    /* ELEM */
> > +     /**
> > +      * Holds the contents of files read from
> > +      * <sysfs>/bus/event_source/devices/<name>/caps/. The contents are pairs
> > +      * of the filename with the value of its contents, for example,
> > +      * max_precise (see above) may have a value of 3.
> > +      */
> > +     struct list_head caps;
> > +     /** Element on pmus list in pmu.c. */
> > +     struct list_head list;
> > +     /** Element on perf_pmu__hybrid_pmus. */
> >       struct list_head hybrid_list;
> >
> > +     /** Features to inhibit when events on this PMU are opened. */
> >       struct {
> > +             /** Disables perf_event_attr exclude_guest and exclude_host. */
> >               bool exclude_guest;
> >       } missing_features;
> >  };
> >
> > +/** A special global PMU used for testing. */
> >  extern struct perf_pmu perf_pmu__fake;
> >
> >  struct perf_pmu_info {
> > @@ -71,21 +132,53 @@ struct perf_pmu_info {
> >
> >  #define UNIT_MAX_LEN 31 /* max length for event unit name */
> >
> > +/**
> > + * An event either read from sysfs or builtin in pmu-events.c, created by
> > + * parsing the pmu-events json files.
> > + */
> >  struct perf_pmu_alias {
> >       char *name;
> > +     /** Optional short description of the event. */
> >       char *desc;
> > +     /** Optional long description. */
> >       char *long_desc;
> > +     /**
> > +      * Optional topic such as cache or pipeline, particularly for json
> > +      * events.
> > +      */
> >       char *topic;
> > +     /** Comma separated parameter list. */
> >       char *str;
> > -     struct list_head terms; /* HEAD struct parse_events_term -> list */
> > -     struct list_head list;  /* ELEM */
> > +     /** Owned list of the original parsed parameters. */
> > +     struct list_head terms;
> > +     /** List element of struct perf_pmu aliases. */
> > +     struct list_head list;
> > +     /** Units for the event, such as bytes or cache lines. */
> >       char unit[UNIT_MAX_LEN+1];
> > +     /** Value to scale read counter values by. */
> >       double scale;
> > +     /**
> > +      * Does the file
> > +      * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.per-pkg or
> > +      * equivalent json value exist and have the value 1.
> > +      */
> >       bool per_pkg;
> > +     /**
> > +      * Does the file
> > +      * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.snapshot
> > +      * exist and have the value 1.
> > +      */
> >       bool snapshot;
> > +     /** Is the event hidden and so not shown in perf list by default. */
> >       bool deprecated;
> > +     /**
> > +      * A metric expression associated with an event. Doing this makes little
> > +      * sense due to scale and unit applying to both.
> > +      */
> >       char *metric_expr;
> > +     /** A name for the metric. unit applying to both. */
> >       char *metric_name;
> > +     /** The name copied from struct perf_pmu. */
> >       char *pmu_name;
> >  };
> >
>
  

On 2022-11-14 9:09 a.m., Ian Rogers wrote:
> On Mon, Nov 14, 2022 at 5:40 AM Liang, Kan <kan.liang@linux.intel.com> wrote:
>>
>>
>>
>> On 2022-11-14 2:51 a.m., Ian Rogers wrote:
>>> Add documentation to struct perf_pmu and the associated structs of
>>> perf_pmu_alias and perf_pmu_format.
>>>
>>> Signed-off-by: Ian Rogers <irogers@google.com>
>>> ---
>>>  tools/perf/util/pmu.c |  14 ++++++
>>>  tools/perf/util/pmu.h | 105 +++++++++++++++++++++++++++++++++++++++---
>>>  2 files changed, 113 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
>>> index 6a86e6af0903..a8f9f47c6ed9 100644
>>> --- a/tools/perf/util/pmu.c
>>> +++ b/tools/perf/util/pmu.c
>>> @@ -31,10 +31,24 @@
>>>
>>>  struct perf_pmu perf_pmu__fake;
>>>
>>> +/**
>>> + * Values from a format file read from <sysfs>/devices/cpu/format/ held in
>>> + * struct perf_pmu. For example, the contents of
>>> + * <sysfs>/devices/cpu/format/event may be "config:0-7" and will be represented
>>> + * here as name="event", value=PERF_PMU_FORMAT_VALUE_CONFIG and bits 0 to 7 will
>>> + * be set.
>>> + */
>>>  struct perf_pmu_format {
>>> +     /** The modifier/file name. */
>>>       char *name;
>>> +     /**
>>> +      * Which config value the format relates to. Supported values are from
>>> +      * PERF_PMU_FORMAT_VALUE_CONFIG to PERF_PMU_FORMAT_VALUE_CONFIG_END.
>>> +      */
>>>       int value;
>>> +     /** Which config bits are set by this format value. */
>>>       DECLARE_BITMAP(bits, PERF_PMU_FORMAT_BITS);
>>> +     /** Element on list within struct perf_pmu. */
>>>       struct list_head list;
>>>  };
>>>
>>> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
>>> index 68e15c38ae71..29571c0f9d15 100644
>>> --- a/tools/perf/util/pmu.h
>>> +++ b/tools/perf/util/pmu.h
>>> @@ -34,30 +34,91 @@ struct perf_pmu_caps {
>>>  };
>>>
>>>  struct perf_pmu {
>>> +     /** The name of the PMU such as "cpu". */
>>>       char *name;
>>> +     /**
>>> +      * Optional alternate name for the PMU determined in architecture
>>> +      * specific code.
>>> +      */
>>>       char *alias_name;
>>> +     /**
>>> +      * Optional PMU identifier read from
>>> +      * <sysfs>/bus/event_source/devices/<name>/identifier.
>>> +      */
>>>       char *id;
>>> +     /**
>>> +      * Perf event attributed type value, read from
>>> +      * <sysfs>/bus/event_source/devices/<name>/type.
>>> +      */
>>>       __u32 type;
>>> +     /**
>>> +      * Can the PMU name be selected as if it were an event?
>>> +      */
>>>       bool selectable;
>>> +     /**
>>> +      * Is the PMU not within the CPU core? Determined by the presence of
>>> +      * <sysfs>/bus/event_source/devices/<name>/cpumask.
>>> +      */
>>>       bool is_uncore;
>>> +     /** Is the PMU name either cpu_core or cpu_atom. */
>>
>> I don't think we want to limit the hybrid names only to cpu_core or
>> cpu_atom. Maybe something as below?
>> /* Is a hybrid CPU PMU, e.g., cpu_core, cpu_atom. */
> 
> Currently the hybrid code only works for cpu_core or cpu_atom, a
> limitation of its implementation. 

I don't think so. See perf_pmu__hybrid_mounted(). If a PMU is named as
"cpu_", we treat it as a hybrid CPU PMU. The cpu_core or cpu_atom should
only be hard coded to specially handle some model-specific cases, e.g.,
mem-loads-aux event.

Thanks,
Kan

> As pointed out in a later patch,
> this bool isn't being used when it could be and I think we can work to
> remove it. It would be possible to remove all uses of this with
> perf_pmu__is_hybrid. As such I think it may be useful to mark the
> hybrid variables in struct perf_pmu as deprecated while we work to
> replace their use with more generic just any PMU code.
> 
> Thanks,
> Ian
> 
>> Thanks,
>> Kan
>>
>>>       bool is_hybrid;
>>> +     /**
>>> +      * Are events auxiliary events? Determined in architecture specific
>>> +      * code.
>>> +      */
>>>       bool auxtrace;
>>> +     /**
>>> +      * Number of levels of :ppp precision supported by the PMU, read from
>>> +      * <sysfs>/bus/event_source/devices/<name>/caps/max_precise.
>>> +      */
>>>       int max_precise;
>>> +     /**
>>> +      * Optional default perf_event_attr determined in architecture specific
>>> +      * code.
>>> +      */
>>>       struct perf_event_attr *default_config;
>>> +     /**
>>> +      * Empty or the contents of either of:
>>> +      * <sysfs>/bus/event_source/devices/<name>/cpumask.
>>> +      * <sysfs>/bus/event_source/devices/<cpu>/cpus.
>>> +      */
>>>       struct perf_cpu_map *cpus;
>>> -     struct list_head format;  /* HEAD struct perf_pmu_format -> list */
>>> -     struct list_head aliases; /* HEAD struct perf_pmu_alias -> list */
>>> +     /**
>>> +      * Holds the contents of files read from
>>> +      * <sysfs>/bus/event_source/devices/<name>/format/. The contents specify
>>> +      * which event parameter changes what config, config1 or config2 bits.
>>> +      */
>>> +     struct list_head format;
>>> +     /**
>>> +      * List of struct perf_pmu_alias. Each alias corresponds to an event
>>> +      * read from <sysfs>/bus/event_source/devices/<name>/events/ or from
>>> +      * json events in pmu-events.c.
>>> +      */
>>> +     struct list_head aliases;
>>> +     /** Has the list caps been initialized? */
>>>       bool caps_initialized;
>>> +     /** The length of the list caps. */
>>>       u32 nr_caps;
>>> -     struct list_head caps;    /* HEAD struct perf_pmu_caps -> list */
>>> -     struct list_head list;    /* ELEM */
>>> +     /**
>>> +      * Holds the contents of files read from
>>> +      * <sysfs>/bus/event_source/devices/<name>/caps/. The contents are pairs
>>> +      * of the filename with the value of its contents, for example,
>>> +      * max_precise (see above) may have a value of 3.
>>> +      */
>>> +     struct list_head caps;
>>> +     /** Element on pmus list in pmu.c. */
>>> +     struct list_head list;
>>> +     /** Element on perf_pmu__hybrid_pmus. */
>>>       struct list_head hybrid_list;
>>>
>>> +     /** Features to inhibit when events on this PMU are opened. */
>>>       struct {
>>> +             /** Disables perf_event_attr exclude_guest and exclude_host. */
>>>               bool exclude_guest;
>>>       } missing_features;
>>>  };
>>>
>>> +/** A special global PMU used for testing. */
>>>  extern struct perf_pmu perf_pmu__fake;
>>>
>>>  struct perf_pmu_info {
>>> @@ -71,21 +132,53 @@ struct perf_pmu_info {
>>>
>>>  #define UNIT_MAX_LEN 31 /* max length for event unit name */
>>>
>>> +/**
>>> + * An event either read from sysfs or builtin in pmu-events.c, created by
>>> + * parsing the pmu-events json files.
>>> + */
>>>  struct perf_pmu_alias {
>>>       char *name;
>>> +     /** Optional short description of the event. */
>>>       char *desc;
>>> +     /** Optional long description. */
>>>       char *long_desc;
>>> +     /**
>>> +      * Optional topic such as cache or pipeline, particularly for json
>>> +      * events.
>>> +      */
>>>       char *topic;
>>> +     /** Comma separated parameter list. */
>>>       char *str;
>>> -     struct list_head terms; /* HEAD struct parse_events_term -> list */
>>> -     struct list_head list;  /* ELEM */
>>> +     /** Owned list of the original parsed parameters. */
>>> +     struct list_head terms;
>>> +     /** List element of struct perf_pmu aliases. */
>>> +     struct list_head list;
>>> +     /** Units for the event, such as bytes or cache lines. */
>>>       char unit[UNIT_MAX_LEN+1];
>>> +     /** Value to scale read counter values by. */
>>>       double scale;
>>> +     /**
>>> +      * Does the file
>>> +      * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.per-pkg or
>>> +      * equivalent json value exist and have the value 1.
>>> +      */
>>>       bool per_pkg;
>>> +     /**
>>> +      * Does the file
>>> +      * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.snapshot
>>> +      * exist and have the value 1.
>>> +      */
>>>       bool snapshot;
>>> +     /** Is the event hidden and so not shown in perf list by default. */
>>>       bool deprecated;
>>> +     /**
>>> +      * A metric expression associated with an event. Doing this makes little
>>> +      * sense due to scale and unit applying to both.
>>> +      */
>>>       char *metric_expr;
>>> +     /** A name for the metric. unit applying to both. */
>>>       char *metric_name;
>>> +     /** The name copied from struct perf_pmu. */
>>>       char *pmu_name;
>>>  };
>>>
  

On Mon, Nov 14, 2022 at 7:26 AM Liang, Kan <kan.liang@linux.intel.com> wrote:
>
>
>
> On 2022-11-14 9:09 a.m., Ian Rogers wrote:
> > On Mon, Nov 14, 2022 at 5:40 AM Liang, Kan <kan.liang@linux.intel.com> wrote:
> >>
> >>
> >>
> >> On 2022-11-14 2:51 a.m., Ian Rogers wrote:
> >>> Add documentation to struct perf_pmu and the associated structs of
> >>> perf_pmu_alias and perf_pmu_format.
> >>>
> >>> Signed-off-by: Ian Rogers <irogers@google.com>
> >>> ---
> >>>  tools/perf/util/pmu.c |  14 ++++++
> >>>  tools/perf/util/pmu.h | 105 +++++++++++++++++++++++++++++++++++++++---
> >>>  2 files changed, 113 insertions(+), 6 deletions(-)
> >>>
> >>> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> >>> index 6a86e6af0903..a8f9f47c6ed9 100644
> >>> --- a/tools/perf/util/pmu.c
> >>> +++ b/tools/perf/util/pmu.c
> >>> @@ -31,10 +31,24 @@
> >>>
> >>>  struct perf_pmu perf_pmu__fake;
> >>>
> >>> +/**
> >>> + * Values from a format file read from <sysfs>/devices/cpu/format/ held in
> >>> + * struct perf_pmu. For example, the contents of
> >>> + * <sysfs>/devices/cpu/format/event may be "config:0-7" and will be represented
> >>> + * here as name="event", value=PERF_PMU_FORMAT_VALUE_CONFIG and bits 0 to 7 will
> >>> + * be set.
> >>> + */
> >>>  struct perf_pmu_format {
> >>> +     /** The modifier/file name. */
> >>>       char *name;
> >>> +     /**
> >>> +      * Which config value the format relates to. Supported values are from
> >>> +      * PERF_PMU_FORMAT_VALUE_CONFIG to PERF_PMU_FORMAT_VALUE_CONFIG_END.
> >>> +      */
> >>>       int value;
> >>> +     /** Which config bits are set by this format value. */
> >>>       DECLARE_BITMAP(bits, PERF_PMU_FORMAT_BITS);
> >>> +     /** Element on list within struct perf_pmu. */
> >>>       struct list_head list;
> >>>  };
> >>>
> >>> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> >>> index 68e15c38ae71..29571c0f9d15 100644
> >>> --- a/tools/perf/util/pmu.h
> >>> +++ b/tools/perf/util/pmu.h
> >>> @@ -34,30 +34,91 @@ struct perf_pmu_caps {
> >>>  };
> >>>
> >>>  struct perf_pmu {
> >>> +     /** The name of the PMU such as "cpu". */
> >>>       char *name;
> >>> +     /**
> >>> +      * Optional alternate name for the PMU determined in architecture
> >>> +      * specific code.
> >>> +      */
> >>>       char *alias_name;
> >>> +     /**
> >>> +      * Optional PMU identifier read from
> >>> +      * <sysfs>/bus/event_source/devices/<name>/identifier.
> >>> +      */
> >>>       char *id;
> >>> +     /**
> >>> +      * Perf event attributed type value, read from
> >>> +      * <sysfs>/bus/event_source/devices/<name>/type.
> >>> +      */
> >>>       __u32 type;
> >>> +     /**
> >>> +      * Can the PMU name be selected as if it were an event?
> >>> +      */
> >>>       bool selectable;
> >>> +     /**
> >>> +      * Is the PMU not within the CPU core? Determined by the presence of
> >>> +      * <sysfs>/bus/event_source/devices/<name>/cpumask.
> >>> +      */
> >>>       bool is_uncore;
> >>> +     /** Is the PMU name either cpu_core or cpu_atom. */
> >>
> >> I don't think we want to limit the hybrid names only to cpu_core or
> >> cpu_atom. Maybe something as below?
> >> /* Is a hybrid CPU PMU, e.g., cpu_core, cpu_atom. */
> >
> > Currently the hybrid code only works for cpu_core or cpu_atom, a
> > limitation of its implementation.
>
> I don't think so. See perf_pmu__hybrid_mounted(). If a PMU is named as
> "cpu_", we treat it as a hybrid CPU PMU. The cpu_core or cpu_atom should
> only be hard coded to specially handle some model-specific cases, e.g.,
> mem-loads-aux event.

Ugh.. Why is a property about something being a CPU named in an Intel
specific term for big little? Why wasn't this generalized? Why are CPU
PMUs assumed to be prefixed cpu_* .. ? The comment is factually
correct, we can hold off deprecating it on the assumption that it'd be
renamed to something more appropriate like is_cpu.

Thanks,
Ian

> Thanks,
> Kan
>
> > As pointed out in a later patch,
> > this bool isn't being used when it could be and I think we can work to
> > remove it. It would be possible to remove all uses of this with
> > perf_pmu__is_hybrid. As such I think it may be useful to mark the
> > hybrid variables in struct perf_pmu as deprecated while we work to
> > replace their use with more generic just any PMU code.
> >
> > Thanks,
> > Ian
> >
> >> Thanks,
> >> Kan
> >>
> >>>       bool is_hybrid;
> >>> +     /**
> >>> +      * Are events auxiliary events? Determined in architecture specific
> >>> +      * code.
> >>> +      */
> >>>       bool auxtrace;
> >>> +     /**
> >>> +      * Number of levels of :ppp precision supported by the PMU, read from
> >>> +      * <sysfs>/bus/event_source/devices/<name>/caps/max_precise.
> >>> +      */
> >>>       int max_precise;
> >>> +     /**
> >>> +      * Optional default perf_event_attr determined in architecture specific
> >>> +      * code.
> >>> +      */
> >>>       struct perf_event_attr *default_config;
> >>> +     /**
> >>> +      * Empty or the contents of either of:
> >>> +      * <sysfs>/bus/event_source/devices/<name>/cpumask.
> >>> +      * <sysfs>/bus/event_source/devices/<cpu>/cpus.
> >>> +      */
> >>>       struct perf_cpu_map *cpus;
> >>> -     struct list_head format;  /* HEAD struct perf_pmu_format -> list */
> >>> -     struct list_head aliases; /* HEAD struct perf_pmu_alias -> list */
> >>> +     /**
> >>> +      * Holds the contents of files read from
> >>> +      * <sysfs>/bus/event_source/devices/<name>/format/. The contents specify
> >>> +      * which event parameter changes what config, config1 or config2 bits.
> >>> +      */
> >>> +     struct list_head format;
> >>> +     /**
> >>> +      * List of struct perf_pmu_alias. Each alias corresponds to an event
> >>> +      * read from <sysfs>/bus/event_source/devices/<name>/events/ or from
> >>> +      * json events in pmu-events.c.
> >>> +      */
> >>> +     struct list_head aliases;
> >>> +     /** Has the list caps been initialized? */
> >>>       bool caps_initialized;
> >>> +     /** The length of the list caps. */
> >>>       u32 nr_caps;
> >>> -     struct list_head caps;    /* HEAD struct perf_pmu_caps -> list */
> >>> -     struct list_head list;    /* ELEM */
> >>> +     /**
> >>> +      * Holds the contents of files read from
> >>> +      * <sysfs>/bus/event_source/devices/<name>/caps/. The contents are pairs
> >>> +      * of the filename with the value of its contents, for example,
> >>> +      * max_precise (see above) may have a value of 3.
> >>> +      */
> >>> +     struct list_head caps;
> >>> +     /** Element on pmus list in pmu.c. */
> >>> +     struct list_head list;
> >>> +     /** Element on perf_pmu__hybrid_pmus. */
> >>>       struct list_head hybrid_list;
> >>>
> >>> +     /** Features to inhibit when events on this PMU are opened. */
> >>>       struct {
> >>> +             /** Disables perf_event_attr exclude_guest and exclude_host. */
> >>>               bool exclude_guest;
> >>>       } missing_features;
> >>>  };
> >>>
> >>> +/** A special global PMU used for testing. */
> >>>  extern struct perf_pmu perf_pmu__fake;
> >>>
> >>>  struct perf_pmu_info {
> >>> @@ -71,21 +132,53 @@ struct perf_pmu_info {
> >>>
> >>>  #define UNIT_MAX_LEN 31 /* max length for event unit name */
> >>>
> >>> +/**
> >>> + * An event either read from sysfs or builtin in pmu-events.c, created by
> >>> + * parsing the pmu-events json files.
> >>> + */
> >>>  struct perf_pmu_alias {
> >>>       char *name;
> >>> +     /** Optional short description of the event. */
> >>>       char *desc;
> >>> +     /** Optional long description. */
> >>>       char *long_desc;
> >>> +     /**
> >>> +      * Optional topic such as cache or pipeline, particularly for json
> >>> +      * events.
> >>> +      */
> >>>       char *topic;
> >>> +     /** Comma separated parameter list. */
> >>>       char *str;
> >>> -     struct list_head terms; /* HEAD struct parse_events_term -> list */
> >>> -     struct list_head list;  /* ELEM */
> >>> +     /** Owned list of the original parsed parameters. */
> >>> +     struct list_head terms;
> >>> +     /** List element of struct perf_pmu aliases. */
> >>> +     struct list_head list;
> >>> +     /** Units for the event, such as bytes or cache lines. */
> >>>       char unit[UNIT_MAX_LEN+1];
> >>> +     /** Value to scale read counter values by. */
> >>>       double scale;
> >>> +     /**
> >>> +      * Does the file
> >>> +      * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.per-pkg or
> >>> +      * equivalent json value exist and have the value 1.
> >>> +      */
> >>>       bool per_pkg;
> >>> +     /**
> >>> +      * Does the file
> >>> +      * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.snapshot
> >>> +      * exist and have the value 1.
> >>> +      */
> >>>       bool snapshot;
> >>> +     /** Is the event hidden and so not shown in perf list by default. */
> >>>       bool deprecated;
> >>> +     /**
> >>> +      * A metric expression associated with an event. Doing this makes little
> >>> +      * sense due to scale and unit applying to both.
> >>> +      */
> >>>       char *metric_expr;
> >>> +     /** A name for the metric. unit applying to both. */
> >>>       char *metric_name;
> >>> +     /** The name copied from struct perf_pmu. */
> >>>       char *pmu_name;
> >>>  };
> >>>
  

On 2022-11-14 12:04 p.m., Ian Rogers wrote:
> On Mon, Nov 14, 2022 at 7:26 AM Liang, Kan <kan.liang@linux.intel.com> wrote:
>>
>>
>>
>> On 2022-11-14 9:09 a.m., Ian Rogers wrote:
>>> On Mon, Nov 14, 2022 at 5:40 AM Liang, Kan <kan.liang@linux.intel.com> wrote:
>>>>
>>>>
>>>>
>>>> On 2022-11-14 2:51 a.m., Ian Rogers wrote:
>>>>> Add documentation to struct perf_pmu and the associated structs of
>>>>> perf_pmu_alias and perf_pmu_format.
>>>>>
>>>>> Signed-off-by: Ian Rogers <irogers@google.com>
>>>>> ---
>>>>>  tools/perf/util/pmu.c |  14 ++++++
>>>>>  tools/perf/util/pmu.h | 105 +++++++++++++++++++++++++++++++++++++++---
>>>>>  2 files changed, 113 insertions(+), 6 deletions(-)
>>>>>
>>>>> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
>>>>> index 6a86e6af0903..a8f9f47c6ed9 100644
>>>>> --- a/tools/perf/util/pmu.c
>>>>> +++ b/tools/perf/util/pmu.c
>>>>> @@ -31,10 +31,24 @@
>>>>>
>>>>>  struct perf_pmu perf_pmu__fake;
>>>>>
>>>>> +/**
>>>>> + * Values from a format file read from <sysfs>/devices/cpu/format/ held in
>>>>> + * struct perf_pmu. For example, the contents of
>>>>> + * <sysfs>/devices/cpu/format/event may be "config:0-7" and will be represented
>>>>> + * here as name="event", value=PERF_PMU_FORMAT_VALUE_CONFIG and bits 0 to 7 will
>>>>> + * be set.
>>>>> + */
>>>>>  struct perf_pmu_format {
>>>>> +     /** The modifier/file name. */
>>>>>       char *name;
>>>>> +     /**
>>>>> +      * Which config value the format relates to. Supported values are from
>>>>> +      * PERF_PMU_FORMAT_VALUE_CONFIG to PERF_PMU_FORMAT_VALUE_CONFIG_END.
>>>>> +      */
>>>>>       int value;
>>>>> +     /** Which config bits are set by this format value. */
>>>>>       DECLARE_BITMAP(bits, PERF_PMU_FORMAT_BITS);
>>>>> +     /** Element on list within struct perf_pmu. */
>>>>>       struct list_head list;
>>>>>  };
>>>>>
>>>>> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
>>>>> index 68e15c38ae71..29571c0f9d15 100644
>>>>> --- a/tools/perf/util/pmu.h
>>>>> +++ b/tools/perf/util/pmu.h
>>>>> @@ -34,30 +34,91 @@ struct perf_pmu_caps {
>>>>>  };
>>>>>
>>>>>  struct perf_pmu {
>>>>> +     /** The name of the PMU such as "cpu". */
>>>>>       char *name;
>>>>> +     /**
>>>>> +      * Optional alternate name for the PMU determined in architecture
>>>>> +      * specific code.
>>>>> +      */
>>>>>       char *alias_name;
>>>>> +     /**
>>>>> +      * Optional PMU identifier read from
>>>>> +      * <sysfs>/bus/event_source/devices/<name>/identifier.
>>>>> +      */
>>>>>       char *id;
>>>>> +     /**
>>>>> +      * Perf event attributed type value, read from
>>>>> +      * <sysfs>/bus/event_source/devices/<name>/type.
>>>>> +      */
>>>>>       __u32 type;
>>>>> +     /**
>>>>> +      * Can the PMU name be selected as if it were an event?
>>>>> +      */
>>>>>       bool selectable;
>>>>> +     /**
>>>>> +      * Is the PMU not within the CPU core? Determined by the presence of
>>>>> +      * <sysfs>/bus/event_source/devices/<name>/cpumask.
>>>>> +      */
>>>>>       bool is_uncore;
>>>>> +     /** Is the PMU name either cpu_core or cpu_atom. */
>>>>
>>>> I don't think we want to limit the hybrid names only to cpu_core or
>>>> cpu_atom. Maybe something as below?
>>>> /* Is a hybrid CPU PMU, e.g., cpu_core, cpu_atom. */
>>>
>>> Currently the hybrid code only works for cpu_core or cpu_atom, a
>>> limitation of its implementation.
>>
>> I don't think so. See perf_pmu__hybrid_mounted(). If a PMU is named as
>> "cpu_", we treat it as a hybrid CPU PMU. The cpu_core or cpu_atom should
>> only be hard coded to specially handle some model-specific cases, e.g.,
>> mem-loads-aux event.
> 
> Ugh.. Why is a property about something being a CPU named in an Intel
> specific term for big little? Why wasn't this generalized? Why are CPU
> PMUs assumed to be prefixed cpu_* .. ? The comment is factually
> correct, we can hold off deprecating it on the assumption that it'd be
> renamed to something more appropriate like is_cpu.

Does any code really use the pmu->is_hybrid?
From what I read, it's only used in the pmu_lookup(), where it's
assigned. It looks like we don't need it in the struct perf_pmu. If so,
let's remove it completely from struct perf_pmu.

Thanks,
Kan
> 
> Thanks,
> Ian
> 
>> Thanks,
>> Kan
>>
>>> As pointed out in a later patch,
>>> this bool isn't being used when it could be and I think we can work to
>>> remove it. It would be possible to remove all uses of this with
>>> perf_pmu__is_hybrid. As such I think it may be useful to mark the
>>> hybrid variables in struct perf_pmu as deprecated while we work to
>>> replace their use with more generic just any PMU code.
>>>
>>> Thanks,
>>> Ian
>>>
>>>> Thanks,
>>>> Kan
>>>>
>>>>>       bool is_hybrid;
>>>>> +     /**
>>>>> +      * Are events auxiliary events? Determined in architecture specific
>>>>> +      * code.
>>>>> +      */
>>>>>       bool auxtrace;
>>>>> +     /**
>>>>> +      * Number of levels of :ppp precision supported by the PMU, read from
>>>>> +      * <sysfs>/bus/event_source/devices/<name>/caps/max_precise.
>>>>> +      */
>>>>>       int max_precise;
>>>>> +     /**
>>>>> +      * Optional default perf_event_attr determined in architecture specific
>>>>> +      * code.
>>>>> +      */
>>>>>       struct perf_event_attr *default_config;
>>>>> +     /**
>>>>> +      * Empty or the contents of either of:
>>>>> +      * <sysfs>/bus/event_source/devices/<name>/cpumask.
>>>>> +      * <sysfs>/bus/event_source/devices/<cpu>/cpus.
>>>>> +      */
>>>>>       struct perf_cpu_map *cpus;
>>>>> -     struct list_head format;  /* HEAD struct perf_pmu_format -> list */
>>>>> -     struct list_head aliases; /* HEAD struct perf_pmu_alias -> list */
>>>>> +     /**
>>>>> +      * Holds the contents of files read from
>>>>> +      * <sysfs>/bus/event_source/devices/<name>/format/. The contents specify
>>>>> +      * which event parameter changes what config, config1 or config2 bits.
>>>>> +      */
>>>>> +     struct list_head format;
>>>>> +     /**
>>>>> +      * List of struct perf_pmu_alias. Each alias corresponds to an event
>>>>> +      * read from <sysfs>/bus/event_source/devices/<name>/events/ or from
>>>>> +      * json events in pmu-events.c.
>>>>> +      */
>>>>> +     struct list_head aliases;
>>>>> +     /** Has the list caps been initialized? */
>>>>>       bool caps_initialized;
>>>>> +     /** The length of the list caps. */
>>>>>       u32 nr_caps;
>>>>> -     struct list_head caps;    /* HEAD struct perf_pmu_caps -> list */
>>>>> -     struct list_head list;    /* ELEM */
>>>>> +     /**
>>>>> +      * Holds the contents of files read from
>>>>> +      * <sysfs>/bus/event_source/devices/<name>/caps/. The contents are pairs
>>>>> +      * of the filename with the value of its contents, for example,
>>>>> +      * max_precise (see above) may have a value of 3.
>>>>> +      */
>>>>> +     struct list_head caps;
>>>>> +     /** Element on pmus list in pmu.c. */
>>>>> +     struct list_head list;
>>>>> +     /** Element on perf_pmu__hybrid_pmus. */
>>>>>       struct list_head hybrid_list;
>>>>>
>>>>> +     /** Features to inhibit when events on this PMU are opened. */
>>>>>       struct {
>>>>> +             /** Disables perf_event_attr exclude_guest and exclude_host. */
>>>>>               bool exclude_guest;
>>>>>       } missing_features;
>>>>>  };
>>>>>
>>>>> +/** A special global PMU used for testing. */
>>>>>  extern struct perf_pmu perf_pmu__fake;
>>>>>
>>>>>  struct perf_pmu_info {
>>>>> @@ -71,21 +132,53 @@ struct perf_pmu_info {
>>>>>
>>>>>  #define UNIT_MAX_LEN 31 /* max length for event unit name */
>>>>>
>>>>> +/**
>>>>> + * An event either read from sysfs or builtin in pmu-events.c, created by
>>>>> + * parsing the pmu-events json files.
>>>>> + */
>>>>>  struct perf_pmu_alias {
>>>>>       char *name;
>>>>> +     /** Optional short description of the event. */
>>>>>       char *desc;
>>>>> +     /** Optional long description. */
>>>>>       char *long_desc;
>>>>> +     /**
>>>>> +      * Optional topic such as cache or pipeline, particularly for json
>>>>> +      * events.
>>>>> +      */
>>>>>       char *topic;
>>>>> +     /** Comma separated parameter list. */
>>>>>       char *str;
>>>>> -     struct list_head terms; /* HEAD struct parse_events_term -> list */
>>>>> -     struct list_head list;  /* ELEM */
>>>>> +     /** Owned list of the original parsed parameters. */
>>>>> +     struct list_head terms;
>>>>> +     /** List element of struct perf_pmu aliases. */
>>>>> +     struct list_head list;
>>>>> +     /** Units for the event, such as bytes or cache lines. */
>>>>>       char unit[UNIT_MAX_LEN+1];
>>>>> +     /** Value to scale read counter values by. */
>>>>>       double scale;
>>>>> +     /**
>>>>> +      * Does the file
>>>>> +      * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.per-pkg or
>>>>> +      * equivalent json value exist and have the value 1.
>>>>> +      */
>>>>>       bool per_pkg;
>>>>> +     /**
>>>>> +      * Does the file
>>>>> +      * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.snapshot
>>>>> +      * exist and have the value 1.
>>>>> +      */
>>>>>       bool snapshot;
>>>>> +     /** Is the event hidden and so not shown in perf list by default. */
>>>>>       bool deprecated;
>>>>> +     /**
>>>>> +      * A metric expression associated with an event. Doing this makes little
>>>>> +      * sense due to scale and unit applying to both.
>>>>> +      */
>>>>>       char *metric_expr;
>>>>> +     /** A name for the metric. unit applying to both. */
>>>>>       char *metric_name;
>>>>> +     /** The name copied from struct perf_pmu. */
>>>>>       char *pmu_name;
>>>>>  };
>>>>>