1 /*
2 * MBWTEST.C
3 *
4 * (c)Copyright 2003 Matthew Dillon. This code is hereby placed in the public
5 * domain.
6 *
7 * Attempt to figure out the L1 and L2 cache sizes and measure memory
8 * bandwidth for the L1 and L2 cache and for non-cache memory.
9 *
10 * $DragonFly: src/test/sysperf/mbwtest.c,v 1.1 2003/11/13 07:10:36 dillon Exp $
11 */
12
13 #include <sys/file.h>
14 #include <sys/time.h>
15 #include <stdio.h>
16 #include <stdlib.h>
17 #include <unistd.h>
18 #include <string.h>
19
20 #define MAXBYTES (16*1024*1024)
21
22 static int bandwidth_test(char *buf, int loops, int bytes, char *msg);
23 static void start_timing(void);
24 static int stop_timing(char *str, long long bytes);
25
26 int
main(int ac,char ** av)27 main(int ac, char **av)
28 {
29 char *buf;
30 int loops;
31 int us1;
32 int us2;
33 long long count1;
34 long long count2;
35 long long count3;
36 long long count4;
37 int bytes1;
38 int bytes2;
39 int bytes3;
40 int bytes4;
41
42 buf = malloc(MAXBYTES * 2);
43 bzero(buf, MAXBYTES * 2);
44
45 /*
46 * Get a baseline for 1/4 second L1 cache timing maximizing the number
47 * of loops. The minimum L1 cache size is 4K.
48 */
49 start_timing();
50 us1 = bandwidth_test(buf, 1000, 4096, NULL); /* uS per 1000 loops */
51 loops = 1000000LL * 1000 / 4 / us1; /* loops for 1/4 sec */
52 count1 = loops * 4096LL;
53 start_timing();
54 us1 = bandwidth_test(buf, loops, 4096, NULL); /* best case timing */
55 printf("."); fflush(stdout); usleep(1000000 / 4);
56
57 /*
58 * Search for the L1 cache size. Look for a 20% difference in bandwidth
59 */
60 bzero(buf, 4096);
61 start_timing();
62 us1 = bandwidth_test(buf, count1 / 4096 + 20, 4096, NULL);
63 for (bytes1 = 8192; bytes1 < MAXBYTES; bytes1 <<= 1) {
64 start_timing();
65 us2 = bandwidth_test(buf, count1 / bytes1 + 20, bytes1, NULL);
66 if (us2 > us1 + us1 / 5)
67 break;
68 }
69 bytes1 >>= 1; /* actual L1 cache size */
70 count2 = count1 * us1 / us2;
71 printf("."); fflush(stdout); usleep(1000000 / 4);
72
73 bytes2 = bytes1 << 1;
74 bzero(buf, bytes2);
75 start_timing();
76 us1 = bandwidth_test(buf, count2 / bytes2 + 20, bytes2, NULL);
77 for (bytes2 <<= 1; bytes2 < MAXBYTES; bytes2 <<= 1) {
78 start_timing();
79 us2 = bandwidth_test(buf, count2 / bytes2 + 20, bytes2, NULL);
80 if (us2 > us1 + us1 / 5)
81 break;
82 }
83 count3 = count2 * us1 / us2;
84 bytes2 >>= 1; /* actual L2 cache size */
85
86 bytes3 = bytes2 << 1;
87 bzero(buf, bytes3);
88 start_timing();
89 us1 = bandwidth_test(buf, count3 / bytes3 + 20, bytes3, NULL);
90 for (bytes3 <<= 1; bytes3 < MAXBYTES; bytes3 <<= 1) {
91 start_timing();
92 us2 = bandwidth_test(buf, count3 / bytes3 + 20, bytes3, NULL);
93 if (us2 > us1 + us1 / 5)
94 break;
95 }
96 count4 = count3 * us1 / us2;
97 bytes3 >>= 1; /* actual L3 cache size */
98
99 /*
100 * Final run to generate output
101 */
102 printf("\nL1 cache size: %d\n", bytes1);
103
104 if (bytes2 == MAXBYTES)
105 printf("L2 cache size: No L2 cache found\n");
106 else
107 printf("L2 cache size: %d\n", bytes2);
108
109 if (bytes3 == MAXBYTES)
110 printf("L3 cache size: No L3 cache found\n");
111 else
112 printf("L3 cache size: %d\n", bytes3);
113
114 sleep(1);
115 start_timing();
116 bandwidth_test(buf, count1 / bytes1 + 20, bytes1, "L1 cache bandwidth");
117 if (bytes2 != MAXBYTES) {
118 start_timing();
119 bandwidth_test(buf, count2 / bytes2 + 20, bytes2,
120 "L2 cache bandwidth");
121 }
122 if (bytes3 != MAXBYTES) {
123 start_timing();
124 bandwidth_test(buf, count3 / bytes3 + 20, bytes3,
125 "L3 cache bandwidth");
126 }
127
128 /*
129 * Set bytes2 to exceed the L2 cache size
130 */
131 bytes4 = bytes3 << 1;
132 if (bytes4 < MAXBYTES)
133 bytes4 <<= 1;
134 start_timing();
135 bandwidth_test(buf, count4 / bytes4 + 20, bytes4, "non-cache bandwidth");
136 return(0);
137 }
138
139 struct timeval tv1;
140 struct timeval tv2;
141
142 static
143 int
bandwidth_test(char * buf,int loops,int bytes,char * msg)144 bandwidth_test(char *buf, int loops, int bytes, char *msg)
145 {
146 register char *bptr;
147 register char *lptr;
148 register int v;
149 int j;
150 int us;
151
152 lptr = buf + bytes;
153 for (j = 0; j < loops; ++j) {
154 for (bptr = buf; bptr < lptr; bptr += 32) {
155 v = *(volatile int *)(bptr + 0);
156 v = *(volatile int *)(bptr + 4);
157 v = *(volatile int *)(bptr + 8);
158 v = *(volatile int *)(bptr + 12);
159 v = *(volatile int *)(bptr + 16);
160 v = *(volatile int *)(bptr + 20);
161 v = *(volatile int *)(bptr + 24);
162 v = *(volatile int *)(bptr + 28);
163 }
164 }
165 us = stop_timing(msg, (long long)bytes * loops);
166 return(us);
167 }
168
169 static
170 void
start_timing(void)171 start_timing(void)
172 {
173 gettimeofday(&tv1, NULL);
174 }
175
176 static
177 int
stop_timing(char * str,long long bytes)178 stop_timing(char *str, long long bytes)
179 {
180 int us;
181
182 gettimeofday(&tv2, NULL);
183
184 us = tv2.tv_usec + 1000000 - tv1.tv_usec +
185 (tv2.tv_sec - tv1.tv_sec - 1) * 1000000;
186 if (str) {
187 printf("%s: %4.2f Mbytes/sec\n",
188 str,
189 (double)bytes * 1000000.0 / ((double)us * 1024.0 * 1024.0));
190 }
191 return(us);
192 }
193
194