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perf pmu: Be lazy about loading event info files from sysfs
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Event info is only needed when an event is parsed or when merging data
from an JSON and sysfs event. Be lazy in its loading to reduce file
accesses.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230824041330.266337-16-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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@captain5050 @acmel
captain5050 authored and acmel committed Aug 24, 2023
1 parent 88ed918 commit 7b723db
Showing 1 changed file with 83 additions and 45 deletions.
128 changes: 83 additions & 45 deletions tools/perf/util/pmu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,11 @@ struct perf_pmu_alias {
struct list_head terms;
/** @list: List element of struct perf_pmu aliases. */
struct list_head list;
/**
* @pmu_name: The name copied from the json struct pmu_event. This can
* differ from the PMU name as it won't have suffixes.
*/
char *pmu_name;
/** @unit: Units for the event, such as bytes or cache lines. */
char unit[UNIT_MAX_LEN+1];
/** @scale: Value to scale read counter values by. */
Expand All @@ -79,11 +84,10 @@ struct perf_pmu_alias {
* default.
*/
bool deprecated;
/**
* @pmu_name: The name copied from the json struct pmu_event. This can
* differ from the PMU name as it won't have suffixes.
*/
char *pmu_name;
/** @from_sysfs: Was the alias from sysfs or a json event? */
bool from_sysfs;
/** @info_loaded: Have the scale, unit and other values been read from disk? */
bool info_loaded;
};

/**
Expand Down Expand Up @@ -280,17 +284,21 @@ int perf_pmu__convert_scale(const char *scale, char **end, double *sval)
return ret;
}

static int perf_pmu__parse_scale(struct perf_pmu_alias *alias, int dirfd, const char *name)
static int perf_pmu__parse_scale(struct perf_pmu *pmu, struct perf_pmu_alias *alias)
{
struct stat st;
ssize_t sret;
size_t len;
char scale[128];
int fd, ret = -1;
char path[PATH_MAX];

scnprintf(path, PATH_MAX, "%s.scale", name);
len = perf_pmu__event_source_devices_scnprintf(path, sizeof(path));
if (!len)
return 0;
scnprintf(path + len, sizeof(path) - len, "%s/%s.scale", pmu->name, alias->name);

fd = openat(dirfd, path, O_RDONLY);
fd = open(path, O_RDONLY);
if (fd == -1)
return -1;

Expand All @@ -312,15 +320,20 @@ static int perf_pmu__parse_scale(struct perf_pmu_alias *alias, int dirfd, const
return ret;
}

static int perf_pmu__parse_unit(struct perf_pmu_alias *alias, int dirfd, const char *name)
static int perf_pmu__parse_unit(struct perf_pmu *pmu, struct perf_pmu_alias *alias)
{
char path[PATH_MAX];
size_t len;
ssize_t sret;
int fd;

scnprintf(path, PATH_MAX, "%s.unit", name);

fd = openat(dirfd, path, O_RDONLY);
len = perf_pmu__event_source_devices_scnprintf(path, sizeof(path));
if (!len)
return 0;
scnprintf(path + len, sizeof(path) - len, "%s/%s.unit", pmu->name, alias->name);

fd = open(path, O_RDONLY);
if (fd == -1)
return -1;

Expand All @@ -343,14 +356,18 @@ static int perf_pmu__parse_unit(struct perf_pmu_alias *alias, int dirfd, const c
}

static int
perf_pmu__parse_per_pkg(struct perf_pmu_alias *alias, int dirfd, const char *name)
perf_pmu__parse_per_pkg(struct perf_pmu *pmu, struct perf_pmu_alias *alias)
{
char path[PATH_MAX];
size_t len;
int fd;

scnprintf(path, PATH_MAX, "%s.per-pkg", name);
len = perf_pmu__event_source_devices_scnprintf(path, sizeof(path));
if (!len)
return 0;
scnprintf(path + len, sizeof(path) - len, "%s/%s.per-pkg", pmu->name, alias->name);

fd = openat(dirfd, path, O_RDONLY);
fd = open(path, O_RDONLY);
if (fd == -1)
return -1;

Expand All @@ -360,15 +377,18 @@ perf_pmu__parse_per_pkg(struct perf_pmu_alias *alias, int dirfd, const char *nam
return 0;
}

static int perf_pmu__parse_snapshot(struct perf_pmu_alias *alias,
int dirfd, const char *name)
static int perf_pmu__parse_snapshot(struct perf_pmu *pmu, struct perf_pmu_alias *alias)
{
char path[PATH_MAX];
size_t len;
int fd;

scnprintf(path, PATH_MAX, "%s.snapshot", name);
len = perf_pmu__event_source_devices_scnprintf(path, sizeof(path));
if (!len)
return 0;
scnprintf(path + len, sizeof(path) - len, "%s/%s.snapshot", pmu->name, alias->name);

fd = openat(dirfd, path, O_RDONLY);
fd = open(path, O_RDONLY);
if (fd == -1)
return -1;

Expand Down Expand Up @@ -429,32 +449,52 @@ static bool assign_str(const char *name, const char *field, char **old_str,
return true;
}

static void read_alias_info(struct perf_pmu *pmu, struct perf_pmu_alias *alias)
{
if (!alias->from_sysfs || alias->info_loaded)
return;

/*
* load unit name and scale if available
*/
perf_pmu__parse_unit(pmu, alias);
perf_pmu__parse_scale(pmu, alias);
perf_pmu__parse_per_pkg(pmu, alias);
perf_pmu__parse_snapshot(pmu, alias);
}

struct update_alias_data {
struct perf_pmu *pmu;
struct perf_pmu_alias *alias;
};

static int update_alias(const struct pmu_event *pe,
const struct pmu_events_table *table __maybe_unused,
void *vdata)
{
struct perf_pmu_alias *alias = vdata;
struct update_alias_data *data = vdata;
int ret = 0;

assign_str(pe->name, "desc", &alias->desc, pe->desc);
assign_str(pe->name, "long_desc", &alias->long_desc, pe->long_desc);
assign_str(pe->name, "topic", &alias->topic, pe->topic);
alias->per_pkg = pe->perpkg;
if (assign_str(pe->name, "value", &alias->str, pe->event)) {
parse_events_terms__purge(&alias->terms);
ret = parse_events_terms(&alias->terms, pe->event, /*input=*/NULL);
read_alias_info(data->pmu, data->alias);
assign_str(pe->name, "desc", &data->alias->desc, pe->desc);
assign_str(pe->name, "long_desc", &data->alias->long_desc, pe->long_desc);
assign_str(pe->name, "topic", &data->alias->topic, pe->topic);
data->alias->per_pkg = pe->perpkg;
if (assign_str(pe->name, "value", &data->alias->str, pe->event)) {
parse_events_terms__purge(&data->alias->terms);
ret = parse_events_terms(&data->alias->terms, pe->event, /*input=*/NULL);
}
if (!ret && pe->unit) {
char *unit;

ret = perf_pmu__convert_scale(pe->unit, &unit, &alias->scale);
ret = perf_pmu__convert_scale(pe->unit, &unit, &data->alias->scale);
if (!ret)
snprintf(alias->unit, sizeof(alias->unit), "%s", unit);
snprintf(data->alias->unit, sizeof(data->alias->unit), "%s", unit);
}
return ret;
}

static int perf_pmu__new_alias(struct perf_pmu *pmu, int dirfd, const char *name,
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)
{
Expand Down Expand Up @@ -498,16 +538,6 @@ static int perf_pmu__new_alias(struct perf_pmu *pmu, int dirfd, const char *name
}

alias->name = strdup(name);
if (dirfd >= 0) {
/*
* load unit name and scale if available
*/
perf_pmu__parse_unit(alias, dirfd, name);
perf_pmu__parse_scale(alias, dirfd, name);
perf_pmu__parse_per_pkg(alias, dirfd, name);
perf_pmu__parse_snapshot(alias, dirfd, name);
}

alias->desc = desc ? strdup(desc) : NULL;
alias->long_desc = long_desc ? strdup(long_desc) :
desc ? strdup(desc) : NULL;
Expand All @@ -522,9 +552,15 @@ static int perf_pmu__new_alias(struct perf_pmu *pmu, int dirfd, const char *name
}
if (!pe) {
/* Update an event from sysfs with json data. */
struct update_alias_data data = {
.pmu = pmu,
.alias = alias,
};

alias->from_sysfs = true;
if (pmu->events_table) {
if (pmu_events_table__find_event(pmu->events_table, pmu, name,
update_alias, alias) == 0)
update_alias, &data) == 0)
pmu->loaded_json_aliases++;
}
}
Expand Down Expand Up @@ -612,7 +648,7 @@ static int pmu_aliases_parse(struct perf_pmu *pmu, int dirfd)
continue;
}

if (perf_pmu__new_alias(pmu, dirfd, name, /*desc=*/ NULL,
if (perf_pmu__new_alias(pmu, name, /*desc=*/ NULL,
/*val=*/ NULL, file, /*pe=*/ NULL) < 0)
pr_debug("Cannot set up %s\n", name);
fclose(file);
Expand Down Expand Up @@ -865,7 +901,7 @@ static int pmu_add_cpu_aliases_map_callback(const struct pmu_event *pe,
{
struct perf_pmu *pmu = vdata;

perf_pmu__new_alias(pmu, -1, 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);
return 0;
}

Expand Down Expand Up @@ -901,7 +937,7 @@ static int pmu_add_sys_aliases_iter_fn(const struct pmu_event *pe,

if (!strcmp(pmu->id, pe->compat) &&
pmu_uncore_alias_match(pe->pmu, pmu->name)) {
perf_pmu__new_alias(pmu, -1,
perf_pmu__new_alias(pmu,
pe->name,
pe->desc,
pe->event,
Expand Down Expand Up @@ -1417,11 +1453,13 @@ static struct perf_pmu_alias *pmu_find_alias(struct perf_pmu *pmu,
}


static int check_info_data(struct perf_pmu_alias *alias,
static int check_info_data(struct perf_pmu *pmu,
struct perf_pmu_alias *alias,
struct perf_pmu_info *info,
struct parse_events_error *err,
int column)
{
read_alias_info(pmu, alias);
/*
* Only one term in event definition can
* define unit, scale and snapshot, fail
Expand Down Expand Up @@ -1491,7 +1529,7 @@ int perf_pmu__check_alias(struct perf_pmu *pmu, struct list_head *head_terms,
return ret;
}

ret = check_info_data(alias, info, err, term->err_term);
ret = check_info_data(pmu, alias, info, err, term->err_term);
if (ret)
return ret;

Expand Down

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