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perf tools: Cache counter names for raw samples on s390

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Searching all event names is slower now that legacy names are
included. Add a cache to avoid long iterative searches. Note, the
cache isn't cleaned up and is as such a memory leak, however, globally
reachable leaks like this aren't treated as leaks by leak sanitizer.

Reported-by: Thomas Richter <tmricht@linux.ibm.com>
Closes: https://lore.kernel.org/linux-perf-users/09943f4f-516c-4b93-877c-e4a64ed61d38@linux.ibm.com/
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Ian Rogers 2025-10-31 12:42:16 -07:00 committed by Namhyung Kim
parent 915c31f0e6
commit 01bc5d2f0d
1 changed files with 50 additions and 5 deletions
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55
tools/perf/util/s390-sample-raw.c
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@ -19,12 +19,14 @@
#include <sys/stat.h>
#include <linux/compiler.h>
#include <linux/err.h>
#include <asm/byteorder.h>
#include "debug.h"
#include "session.h"
#include "evlist.h"
#include "color.h"
#include "hashmap.h"
#include "sample-raw.h"
#include "s390-cpumcf-kernel.h"
#include "util/pmu.h"
@ -132,8 +134,8 @@ static int get_counterset_start(int setnr)
}
struct get_counter_name_data {
int wanted;
char *result;
long wanted;
const char *result;
};
static int get_counter_name_callback(void *vdata, struct pmu_event_info *info)
@ -151,12 +153,22 @@ static int get_counter_name_callback(void *vdata, struct pmu_event_info *info)
rc = sscanf(event_str, "event=%x", &event_nr);
if (rc == 1 && event_nr == data->wanted) {
data->result = strdup(info->name);
data->result = info->name;
return 1; /* Terminate the search. */
}
return 0;
}
static size_t get_counter_name_hash_fn(long key, void *ctx __maybe_unused)
{
return key;
}
static bool get_counter_name_hashmap_equal_fn(long key1, long key2, void *ctx __maybe_unused)
{
return key1 == key2;
}
/* Scan the PMU and extract the logical name of a counter from the event. Input
* is the counter set and counter number with in the set. Construct the event
* number and use this as key. If they match return the name of this counter.
@ -164,17 +176,50 @@ static int get_counter_name_callback(void *vdata, struct pmu_event_info *info)
*/
static char *get_counter_name(int set, int nr, struct perf_pmu *pmu)
{
static struct hashmap *cache;
static struct perf_pmu *cache_pmu;
long cache_key = get_counterset_start(set) + nr;
struct get_counter_name_data data = {
.wanted = get_counterset_start(set) + nr,
.wanted = cache_key,
.result = NULL,
};
char *result = NULL;
if (!pmu)
return NULL;
if (cache_pmu == pmu && hashmap__find(cache, cache_key, &result))
return strdup(result);
perf_pmu__for_each_event(pmu, /*skip_duplicate_pmus=*/ true,
&data, get_counter_name_callback);
return data.result;
result = strdup(data.result ?: "<unknown>");
if (cache_pmu == NULL) {
struct hashmap *tmp = hashmap__new(get_counter_name_hash_fn,
get_counter_name_hashmap_equal_fn,
/*ctx=*/NULL);
if (!IS_ERR(tmp)) {
cache = tmp;
cache_pmu = pmu;
}
}
if (cache_pmu == pmu && result) {
char *old_value = NULL, *new_value = strdup(result);
if (new_value) {
hashmap__set(cache, cache_key, new_value, /*old_key=*/NULL, &old_value);
/*
* Free in case of a race, but resizing would be broken
* in that case.
*/
free(old_value);
}
}
return result;
}
static void s390_cpumcfdg_dump(struct perf_pmu *pmu, struct perf_sample *sample)