Re: [PATCH v1 1/9] perf pmu: Add documentation

Adrian Hunter
2022-11-14T08:56:01Z

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;
> };
>