Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2#include <err.h>
3#include <errno.h>
4#include <stdio.h>
5#include <stdlib.h>
6#include <sys/prctl.h>
7
8#include "futex.h"
9
10#ifndef PR_FUTEX_HASH
11#define PR_FUTEX_HASH 78
12# define PR_FUTEX_HASH_SET_SLOTS 1
13# define PR_FUTEX_HASH_GET_SLOTS 2
14#endif // PR_FUTEX_HASH
15
16void futex_set_nbuckets_param(struct bench_futex_parameters *params)
17{
18 int ret;
19
20 if (params->nbuckets < 0)
21 return;
22
23 ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, params->nbuckets, 0);
24 if (ret) {
25 printf("Requesting %d hash buckets failed: %d/%m\n",
26 params->nbuckets, ret);
27 err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)");
28 }
29}
30
31void futex_print_nbuckets(struct bench_futex_parameters *params)
32{
33 char *futex_hash_mode;
34 int ret;
35
36 ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_GET_SLOTS);
37 if (params->nbuckets >= 0) {
38 if (ret != params->nbuckets) {
39 if (ret < 0) {
40 printf("Can't query number of buckets: %m\n");
41 err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)");
42 }
43 printf("Requested number of hash buckets does not currently used.\n");
44 printf("Requested: %d in usage: %d\n", params->nbuckets, ret);
45 err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)");
46 }
47 if (params->nbuckets == 0)
48 ret = asprintf(&futex_hash_mode, "Futex hashing: global hash");
49 else
50 ret = asprintf(&futex_hash_mode, "Futex hashing: %d hash buckets",
51 params->nbuckets);
52 } else {
53 if (ret <= 0) {
54 ret = asprintf(&futex_hash_mode, "Futex hashing: global hash");
55 } else {
56 ret = asprintf(&futex_hash_mode, "Futex hashing: auto resized to %d buckets",
57 ret);
58 }
59 }
60 if (ret < 0)
61 err(EXIT_FAILURE, "ENOMEM, futex_hash_mode");
62 printf("%s\n", futex_hash_mode);
63 free(futex_hash_mode);
64}