aboutsummaryrefslogtreecommitdiff
path: root/tests/atomic64-bench.c
blob: 71692560edf37882a22dde21c740c9aaeed61214 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
/*
 * Copyright (C) 2018, Emilio G. Cota <cota@braap.org>
 *
 * License: GNU GPL, version 2 or later.
 *   See the COPYING file in the top-level directory.
 */
#include "qemu/osdep.h"
#include "qemu/thread.h"
#include "qemu/host-utils.h"
#include "qemu/processor.h"

struct thread_info {
    uint64_t r;
    uint64_t accesses;
} QEMU_ALIGNED(64);

struct count {
    int64_t i64;
} QEMU_ALIGNED(64);

static QemuThread *threads;
static struct thread_info *th_info;
static unsigned int n_threads = 1;
static unsigned int n_ready_threads;
static struct count *counts;
static unsigned int duration = 1;
static unsigned int range = 1024;
static bool test_start;
static bool test_stop;

static const char commands_string[] =
    " -d = duration in seconds\n"
    " -n = number of threads\n"
    " -r = range (will be rounded up to pow2)";

static void usage_complete(char *argv[])
{
    fprintf(stderr, "Usage: %s [options]\n", argv[0]);
    fprintf(stderr, "options:\n%s\n", commands_string);
}

/*
 * From: https://en.wikipedia.org/wiki/Xorshift
 * This is faster than rand_r(), and gives us a wider range (RAND_MAX is only
 * guaranteed to be >= INT_MAX).
 */
static uint64_t xorshift64star(uint64_t x)
{
    x ^= x >> 12; /* a */
    x ^= x << 25; /* b */
    x ^= x >> 27; /* c */
    return x * UINT64_C(2685821657736338717);
}

static void *thread_func(void *arg)
{
    struct thread_info *info = arg;

    atomic_inc(&n_ready_threads);
    while (!atomic_read(&test_start)) {
        cpu_relax();
    }

    while (!atomic_read(&test_stop)) {
        unsigned int index;

        info->r = xorshift64star(info->r);
        index = info->r & (range - 1);
        atomic_read_i64(&counts[index].i64);
        info->accesses++;
    }
    return NULL;
}

static void run_test(void)
{
    unsigned int remaining;
    unsigned int i;

    while (atomic_read(&n_ready_threads) != n_threads) {
        cpu_relax();
    }
    atomic_set(&test_start, true);
    do {
        remaining = sleep(duration);
    } while (remaining);
    atomic_set(&test_stop, true);

    for (i = 0; i < n_threads; i++) {
        qemu_thread_join(&threads[i]);
    }
}

static void create_threads(void)
{
    unsigned int i;

    threads = g_new(QemuThread, n_threads);
    th_info = g_new(struct thread_info, n_threads);
    counts = g_malloc0_n(range, sizeof(*counts));

    for (i = 0; i < n_threads; i++) {
        struct thread_info *info = &th_info[i];

        info->r = (i + 1) ^ time(NULL);
        info->accesses = 0;
        qemu_thread_create(&threads[i], NULL, thread_func, info,
                           QEMU_THREAD_JOINABLE);
    }
}

static void pr_params(void)
{
    printf("Parameters:\n");
    printf(" # of threads:      %u\n", n_threads);
    printf(" duration:          %u\n", duration);
    printf(" ops' range:        %u\n", range);
}

static void pr_stats(void)
{
    unsigned long long val = 0;
    double tx;
    int i;

    for (i = 0; i < n_threads; i++) {
        val += th_info[i].accesses;
    }
    tx = val / duration / 1e6;

    printf("Results:\n");
    printf("Duration:            %u s\n", duration);
    printf(" Throughput:         %.2f Mops/s\n", tx);
    printf(" Throughput/thread:  %.2f Mops/s/thread\n", tx / n_threads);
}

static void parse_args(int argc, char *argv[])
{
    int c;

    for (;;) {
        c = getopt(argc, argv, "hd:n:r:");
        if (c < 0) {
            break;
        }
        switch (c) {
        case 'h':
            usage_complete(argv);
            exit(0);
        case 'd':
            duration = atoi(optarg);
            break;
        case 'n':
            n_threads = atoi(optarg);
            break;
        case 'r':
            range = pow2ceil(atoi(optarg));
            break;
        }
    }
}

int main(int argc, char *argv[])
{
    parse_args(argc, argv);
    pr_params();
    create_threads();
    run_test();
    pr_stats();
    return 0;
}