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// SPDX-License-Identifier: GPL-2.0
#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/prctl.h>
#include "futex.h"
#ifndef PR_FUTEX_HASH
#define PR_FUTEX_HASH 78
# define PR_FUTEX_HASH_SET_SLOTS 1
# define FH_FLAG_IMMUTABLE (1ULL << 0)
# define PR_FUTEX_HASH_GET_SLOTS 2
# define PR_FUTEX_HASH_GET_IMMUTABLE 3
#endif // PR_FUTEX_HASH
void futex_set_nbuckets_param(struct bench_futex_parameters *params)
{
unsigned long flags;
int ret;
if (params->nbuckets < 0)
return;
flags = params->buckets_immutable ? FH_FLAG_IMMUTABLE : 0;
ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, params->nbuckets, flags);
if (ret) {
printf("Requesting %d hash buckets failed: %d/%m\n",
params->nbuckets, ret);
err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)");
}
}
void futex_print_nbuckets(struct bench_futex_parameters *params)
{
char *futex_hash_mode;
int ret;
ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_GET_SLOTS);
if (params->nbuckets >= 0) {
if (ret != params->nbuckets) {
if (ret < 0) {
printf("Can't query number of buckets: %m\n");
err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)");
}
printf("Requested number of hash buckets does not currently used.\n");
printf("Requested: %d in usage: %d\n", params->nbuckets, ret);
err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)");
}
if (params->nbuckets == 0) {
ret = asprintf(&futex_hash_mode, "Futex hashing: global hash");
} else {
ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_GET_IMMUTABLE);
if (ret < 0) {
printf("Can't check if the hash is immutable: %m\n");
err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)");
}
ret = asprintf(&futex_hash_mode, "Futex hashing: %d hash buckets %s",
params->nbuckets,
ret == 1 ? "(immutable)" : "");
}
} else {
if (ret <= 0) {
ret = asprintf(&futex_hash_mode, "Futex hashing: global hash");
} else {
ret = asprintf(&futex_hash_mode, "Futex hashing: auto resized to %d buckets",
ret);
}
}
if (ret < 0)
err(EXIT_FAILURE, "ENOMEM, futex_hash_mode");
printf("%s\n", futex_hash_mode);
free(futex_hash_mode);
}
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