1 /* This testcase is part of GDB, the GNU debugger. 2 3 Copyright 2010-2023 Free Software Foundation, Inc. 4 5 This program is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 3 of the License, or 8 (at your option) any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 17 18 /* This program tests tracepoint speed. It consists of two identical 19 loops, which in normal execution will run for exactly the same 20 amount of time. A tracepoint in the second loop will slow it down 21 by some amount, and then the program will report the slowdown 22 observed. */ 23 24 /* While primarily designed for the testsuite, it can also be used 25 for interactive testing. */ 26 27 #include <stdio.h> 28 #include <time.h> 29 #include <sys/time.h> 30 #include <sys/resource.h> 31 #include <unistd.h> 32 33 int trace_speed_test (void); 34 35 /* We mark these globals as volatile so the speed-measuring loops 36 don't get totally emptied out at high optimization levels. */ 37 38 volatile int globfoo, globfoo2, globfoo3; 39 40 volatile short globarr[80000]; 41 42 int init_iters = 10 * 1000; 43 44 int iters; 45 46 int max_iters = 1000 * 1000 * 1000; 47 48 int numtps = 1; 49 50 unsigned long long now2, now3, now4, now5; 51 int total1, total2, idelta, mindelta, nsdelta; 52 int nspertp = 0; 53 54 /* Return CPU usage (both user and system - trap-based tracepoints use 55 a bunch of system time). */ 56 57 unsigned long long 58 myclock () 59 { 60 struct timeval tm; 61 gettimeofday (&tm, NULL); 62 return (((unsigned long long) tm.tv_sec) * 1000000) + tm.tv_usec; 63 } 64 65 int 66 main(int argc, char **argv) 67 { 68 int problem; 69 70 iters = init_iters; 71 72 while (1) 73 { 74 numtps = 1; /* set pre-run breakpoint here */ 75 76 /* Keep trying the speed test, with more iterations, until 77 we get to a reasonable number. */ 78 while ((problem = trace_speed_test())) 79 { 80 /* If iteration isn't working, give up. */ 81 if (iters > max_iters) 82 { 83 printf ("Gone over %d iterations, giving up\n", max_iters); 84 break; 85 } 86 if (problem < 0) 87 { 88 printf ("Negative times, giving up\n"); 89 break; 90 } 91 92 iters *= 2; 93 printf ("Doubled iterations to %d\n", iters); 94 } 95 96 printf ("Tracepoint time is %d ns\n", nspertp); 97 98 /* This is for the benefit of interactive testing and attaching, 99 keeps the program from pegging the machine. */ 100 sleep (1); /* set post-run breakpoint here */ 101 102 /* Issue a little bit of output periodically, so we can see if 103 program is alive or hung. */ 104 printf ("%s keeping busy, clock=%llu\n", argv[0], myclock ()); 105 } 106 return 0; 107 } 108 109 int 110 trace_speed_test (void) 111 { 112 int i; 113 114 /* Overall loop run time deltas under 1 ms are likely noise and 115 should be ignored. */ 116 mindelta = 1000; 117 118 // The bodies of the two loops following must be identical. 119 120 now2 = myclock (); 121 globfoo2 = 1; 122 for (i = 0; i < iters; ++i) 123 { 124 globfoo2 *= 45; 125 globfoo2 += globfoo + globfoo3; 126 globfoo2 *= globfoo + globfoo3; 127 globfoo2 -= globarr[4] + globfoo3; 128 globfoo2 *= globfoo + globfoo3; 129 globfoo2 += globfoo + globfoo3; 130 } 131 now3 = myclock (); 132 total1 = now3 - now2; 133 134 now4 = myclock (); 135 globfoo2 = 1; 136 for (i = 0; i < iters; ++i) 137 { 138 globfoo2 *= 45; 139 globfoo2 += globfoo + globfoo3; /* set tracepoint here */ 140 globfoo2 *= globfoo + globfoo3; 141 globfoo2 -= globarr[4] + globfoo3; 142 globfoo2 *= globfoo + globfoo3; 143 globfoo2 += globfoo + globfoo3; 144 } 145 now5 = myclock (); 146 total2 = now5 - now4; 147 148 /* Report on the test results. */ 149 150 nspertp = 0; 151 152 idelta = total2 - total1; 153 154 printf ("Loops took %d usec and %d usec, delta is %d usec, %d iterations\n", 155 total1, total2, idelta, iters); 156 157 /* If the second loop seems to run faster, things are weird so give up. */ 158 if (idelta < 0) 159 return -1; 160 161 if (idelta > mindelta 162 /* Total test time should be between 15 and 30 seconds. */ 163 && (total1 + total2) > (15 * 1000000) 164 && (total1 + total2) < (30 * 1000000)) 165 { 166 nsdelta = (((unsigned long long) idelta) * 1000) / iters; 167 printf ("Second loop took %d ns longer per iter than first\n", nsdelta); 168 nspertp = nsdelta / numtps; 169 printf ("%d ns per tracepoint\n", nspertp); 170 printf ("Base iteration time %d ns\n", 171 ((int) (((unsigned long long) total1) * 1000) / iters)); 172 printf ("Total test time %d secs\n", ((int) ((now5 - now2) / 1000000))); 173 174 /* Speed test ran with no problem. */ 175 return 0; 176 } 177 178 /* The test run was too brief, or otherwise not useful. */ 179 return 1; 180 } 181