Messages in this thread | | | Date | Mon, 14 Nov 2022 13:49:56 -0500 | Subject | Re: [PATCH v1 1/9] perf pmu: Add documentation | From | "Liang, Kan" <> |
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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; >>>>> }; >>>>>
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