Messages in this thread | | | From | Ian Rogers <> | Date | Mon, 14 Nov 2022 09:04:01 -0800 | Subject | Re: [PATCH v1 1/9] perf pmu: Add documentation |
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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; > >>> }; > >>>
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