xref: /openbmc/qemu/tests/bench/atomic_add-bench.c (revision ffe98631)
1 #include "qemu/osdep.h"
2 #include "qemu/thread.h"
3 #include "qemu/host-utils.h"
4 #include "qemu/processor.h"
5 #include "qemu/memalign.h"
6 
7 struct thread_info {
8     uint64_t r;
9 } QEMU_ALIGNED(64);
10 
11 struct count {
12     QemuMutex lock;
13     unsigned long val;
14 } QEMU_ALIGNED(64);
15 
16 static QemuThread *threads;
17 static struct thread_info *th_info;
18 static unsigned int n_threads = 1;
19 static unsigned int n_ready_threads;
20 static struct count *counts;
21 static unsigned int duration = 1;
22 static unsigned int range = 1024;
23 static bool use_mutex;
24 static bool test_start;
25 static bool test_stop;
26 
27 static const char commands_string[] =
28     " -n = number of threads\n"
29     " -m = use mutexes instead of atomic increments\n"
30     " -p = enable sync profiler\n"
31     " -d = duration in seconds\n"
32     " -r = range (will be rounded up to pow2)";
33 
34 static void usage_complete(char *argv[])
35 {
36     fprintf(stderr, "Usage: %s [options]\n", argv[0]);
37     fprintf(stderr, "options:\n%s\n", commands_string);
38 }
39 
40 /*
41  * From: https://en.wikipedia.org/wiki/Xorshift
42  * This is faster than rand_r(), and gives us a wider range (RAND_MAX is only
43  * guaranteed to be >= INT_MAX).
44  */
45 static uint64_t xorshift64star(uint64_t x)
46 {
47     x ^= x >> 12; /* a */
48     x ^= x << 25; /* b */
49     x ^= x >> 27; /* c */
50     return x * UINT64_C(2685821657736338717);
51 }
52 
53 static void *thread_func(void *arg)
54 {
55     struct thread_info *info = arg;
56 
57     qatomic_inc(&n_ready_threads);
58     while (!qatomic_read(&test_start)) {
59         cpu_relax();
60     }
61 
62     while (!qatomic_read(&test_stop)) {
63         unsigned int index;
64 
65         info->r = xorshift64star(info->r);
66         index = info->r & (range - 1);
67         if (use_mutex) {
68             qemu_mutex_lock(&counts[index].lock);
69             counts[index].val += 1;
70             qemu_mutex_unlock(&counts[index].lock);
71         } else {
72             qatomic_inc(&counts[index].val);
73         }
74     }
75     return NULL;
76 }
77 
78 static void run_test(void)
79 {
80     unsigned int i;
81 
82     while (qatomic_read(&n_ready_threads) != n_threads) {
83         cpu_relax();
84     }
85 
86     qatomic_set(&test_start, true);
87     g_usleep(duration * G_USEC_PER_SEC);
88     qatomic_set(&test_stop, true);
89 
90     for (i = 0; i < n_threads; i++) {
91         qemu_thread_join(&threads[i]);
92     }
93 }
94 
95 static void create_threads(void)
96 {
97     unsigned int i;
98 
99     threads = g_new(QemuThread, n_threads);
100     th_info = g_new(struct thread_info, n_threads);
101     counts = qemu_memalign(64, sizeof(*counts) * range);
102     memset(counts, 0, sizeof(*counts) * range);
103     for (i = 0; i < range; i++) {
104         qemu_mutex_init(&counts[i].lock);
105     }
106 
107     for (i = 0; i < n_threads; i++) {
108         struct thread_info *info = &th_info[i];
109 
110         info->r = (i + 1) ^ time(NULL);
111         qemu_thread_create(&threads[i], NULL, thread_func, info,
112                            QEMU_THREAD_JOINABLE);
113     }
114 }
115 
116 static void pr_params(void)
117 {
118     printf("Parameters:\n");
119     printf(" # of threads:      %u\n", n_threads);
120     printf(" duration:          %u\n", duration);
121     printf(" ops' range:        %u\n", range);
122 }
123 
124 static void pr_stats(void)
125 {
126     unsigned long long val = 0;
127     unsigned int i;
128     double tx;
129 
130     for (i = 0; i < range; i++) {
131         val += counts[i].val;
132     }
133     tx = val / duration / 1e6;
134 
135     printf("Results:\n");
136     printf("Duration:            %u s\n", duration);
137     printf(" Throughput:         %.2f Mops/s\n", tx);
138     printf(" Throughput/thread:  %.2f Mops/s/thread\n", tx / n_threads);
139 }
140 
141 static void parse_args(int argc, char *argv[])
142 {
143     int c;
144 
145     for (;;) {
146         c = getopt(argc, argv, "hd:n:mpr:");
147         if (c < 0) {
148             break;
149         }
150         switch (c) {
151         case 'h':
152             usage_complete(argv);
153             exit(0);
154         case 'd':
155             duration = atoi(optarg);
156             break;
157         case 'n':
158             n_threads = atoi(optarg);
159             break;
160         case 'm':
161             use_mutex = true;
162             break;
163         case 'p':
164             qsp_enable();
165             break;
166         case 'r':
167             range = pow2ceil(atoi(optarg));
168             break;
169         }
170     }
171 }
172 
173 int main(int argc, char *argv[])
174 {
175     parse_args(argc, argv);
176     pr_params();
177     create_threads();
178     run_test();
179     pr_stats();
180     return 0;
181 }
182