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SubjectRe: [PATCH v1] perf pmu: Count sys and cpuid json events separately
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On 10/05/2024 18:36, Ian Rogers wrote:
> Sys events are eagerly loaded as each event has a compat option that
> may mean the event is or isn't associated with the PMU. These
> shouldn't be counted as loaded_json_events as that is used for json
> events matching the CPUID that may or may not have been loaded. The
> mismatch causes issues on ARM64 that uses sys events.
>
> Reported-by: Jia He <justin.he@arm.com>
> Closes: https://urldefense.com/v3/__https://lore.kernel.org/lkml/20240510024729.1075732-1-justin.he@arm.com/__;!!ACWV5N9M2RV99hQ!KVhaRPLqS7T1s6p506Gv0zFNdlTR1exCUrXM3UIDr0EdrRFwrzM3W9ntkxw42jNeG01P7H78r0c-nz8FVQQ$
> Fixes: e6ff1eed3584 ("perf pmu: Lazily add JSON events")
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/util/pmu.c | 70 ++++++++++++++++++++++++++++++-------------
> tools/perf/util/pmu.h | 6 ++--
> 2 files changed, 53 insertions(+), 23 deletions(-)
>
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index b3b072feef02..888ce9912275 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -36,6 +36,18 @@ struct perf_pmu perf_pmu__fake = {
>
> #define UNIT_MAX_LEN 31 /* max length for event unit name */
>
> +enum event_source {
> + /* An event loaded from /sys/devices/<pmu>/events. */
> + EVENT_SRC_SYSFS,
> + /* An event loaded from a CPUID matched json file. */
> + EVENT_SRC_CPU_JSON,
> + /*
> + * An event loaded from a /sys/devices/<pmu>/identifier matched json
> + * file.
> + */
> + EVENT_SRC_SYS_JSON,

If a json sys event aliases to a EVENT_SRC_SYSFS event, this is
considered a EVENT_SRC_SYS_JSON event source, right?

> +};
> +
> /**
> * struct perf_pmu_alias - An event either read from sysfs or builtin in
> * pmu-events.c, created by parsing the pmu-events json files.
> @@ -521,7 +533,7 @@ static int update_alias(const struct pmu_event *pe,
>
> static int perf_pmu__new_alias(struct perf_pmu *pmu, const char *name,
> const char *desc, const char *val, FILE *val_fd,
> - const struct pmu_event *pe)
> + const struct pmu_event *pe, enum event_source src)
> {
> struct perf_pmu_alias *alias;
> int ret;
> @@ -574,25 +586,30 @@ static int perf_pmu__new_alias(struct perf_pmu *pmu, const char *name,
> }
> snprintf(alias->unit, sizeof(alias->unit), "%s", unit);
> }
> - if (!pe) {
> - /* Update an event from sysfs with json data. */
> - struct update_alias_data data = {
> - .pmu = pmu,
> - .alias = alias,
> - };
> -
> + switch (src) {
> + default:
> + case EVENT_SRC_SYSFS:
> alias->from_sysfs = true;
> if (pmu->events_table) {
> + /* Update an event from sysfs with json data. */
> + struct update_alias_data data = {
> + .pmu = pmu,
> + .alias = alias,
> + };
> if (pmu_events_table__find_event(pmu->events_table, pmu, name,
> update_alias, &data) == 0)
> - pmu->loaded_json_aliases++;
> + pmu->cpu_json_aliases++;

seems strange that matching for EVENT_SRC_SYSFS increases
pmu->cpu_json_aliases

> }
> - }
> -
> - if (!pe)
> pmu->sysfs_aliases++;
> - else
> - pmu->loaded_json_aliases++;
> + break;
> + case EVENT_SRC_CPU_JSON:
> + pmu->cpu_json_aliases++;
> + break;
> + case EVENT_SRC_SYS_JSON:
> + pmu->sys_json_aliases++;
> + break;
> +
> + }
> list_add_tail(&alias->list, &pmu->aliases);
> return 0;
> }
> @@ -653,7 +670,8 @@ static int __pmu_aliases_parse(struct perf_pmu *pmu, int events_dir_fd)
> }
>
> if (perf_pmu__new_alias(pmu, name, /*desc=*/ NULL,
> - /*val=*/ NULL, file, /*pe=*/ NULL) < 0)
> + /*val=*/ NULL, file, /*pe=*/ NULL,
> + EVENT_SRC_SYSFS) < 0)
> pr_debug("Cannot set up %s\n", name);
> fclose(file);
> }
> @@ -946,7 +964,8 @@ static int pmu_add_cpu_aliases_map_callback(const struct pmu_event *pe,
> {
> struct perf_pmu *pmu = vdata;
>
> - perf_pmu__new_alias(pmu, pe->name, pe->desc, pe->event, /*val_fd=*/ NULL, pe);
> + perf_pmu__new_alias(pmu, pe->name, pe->desc, pe->event, /*val_fd=*/ NULL,
> + pe, EVENT_SRC_CPU_JSON);
> return 0;
> }
>
> @@ -981,13 +1000,14 @@ static int pmu_add_sys_aliases_iter_fn(const struct pmu_event *pe,
> return 0;
>
> if (pmu_uncore_alias_match(pe->pmu, pmu->name) &&
> - pmu_uncore_identifier_match(pe->compat, pmu->id)) {
> + pmu_uncore_identifier_match(pe->compat, pmu->id)) {
> perf_pmu__new_alias(pmu,
> pe->name,
> pe->desc,
> pe->event,
> /*val_fd=*/ NULL,
> - pe);
> + pe,
> + EVENT_SRC_SYS_JSON);
> }
>
> return 0;
> @@ -1082,6 +1102,12 @@ struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char
> pmu->max_precise = pmu_max_precise(dirfd, pmu);
> pmu->alias_name = pmu_find_alias_name(pmu, dirfd);
> pmu->events_table = perf_pmu__find_events_table(pmu);
> + /*
> + * Load the sys json events/aliases when loading the PMU as each event
> + * may have a different compat regular expression. We therefore can't
> + * know the number of sys json events/aliases without computing the
> + * regular expressions for them all.
> + */
> pmu_add_sys_aliases(pmu);
> list_add_tail(&pmu->list, pmus);
>
> @@ -1739,12 +1765,14 @@ size_t perf_pmu__num_events(struct perf_pmu *pmu)
> size_t nr;
>
> pmu_aliases_parse(pmu);
> - nr = pmu->sysfs_aliases;
> + nr = pmu->sysfs_aliases + pmu->sys_json_aliases;;
>
> if (pmu->cpu_aliases_added)
> - nr += pmu->loaded_json_aliases;
> + nr += pmu->cpu_json_aliases;
> else if (pmu->events_table)
> - nr += pmu_events_table__num_events(pmu->events_table, pmu) - pmu->loaded_json_aliases;
> + nr += pmu_events_table__num_events(pmu->events_table, pmu) - pmu->cpu_json_aliases;
> + else
> + assert(pmu->cpu_json_aliases == 0);
>
> return pmu->selectable ? nr + 1 : nr;
> }
> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> index 561716aa2b25..b2d3fd291f02 100644
> --- a/tools/perf/util/pmu.h
> +++ b/tools/perf/util/pmu.h
> @@ -123,8 +123,10 @@ struct perf_pmu {
> const struct pmu_events_table *events_table;
> /** @sysfs_aliases: Number of sysfs aliases loaded. */
> uint32_t sysfs_aliases;
> - /** @sysfs_aliases: Number of json event aliases loaded. */
> - uint32_t loaded_json_aliases;
> + /** @cpu_json_aliases: Number of json event aliases loaded specific to the CPUID. */
> + uint32_t cpu_json_aliases;

it seems strange that we allow a pmu to have both cpu_json_aliases and
sys_json_aliases count. A union could be used, but that would complicate
things.

> + /** @sys_json_aliases: Number of json event aliases loaded matching the PMU's identifier. */
> + uint32_t sys_json_aliases;
> /** @sysfs_aliases_loaded: Are sysfs aliases loaded from disk? */
> bool sysfs_aliases_loaded;
> /**


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