我在我的 Mac 上用 C 来做基准测试。此处的代码可以编译并运行，但输出中会出现大约 1Hz 的故障。该程序“应该”每 2 毫秒中断一次，并报告上次中断时间的数据。默认设置是打印以下内容到终端
eventCounter \t elapsedTime \t jitter \t sumJitter
eventCounter 很明显，每次中断发生它就计数
elapsedTime 以美国为单位
抖动是elapsedTime减去2000(2mS)
sumJitter是抖动+抖动
几乎每秒一次，elapsedTime 的结果崩溃到大约 -1,000,000，这太疯狂了，因为这意味着我制造了一台时间机器......现在我已经过去了......大约 16 分钟... 我觉得没什么不同。
这是代码
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <signal.h>
#include <unistd.h>
#include <time.h>
#define OPT_R_MIN 0
#define OPT_R_MAX 5000
#define OPT_R_DEF 100
#define OPT_U_MIN 100
#define OPT_U_MAX 2000000000 // 2K seconds
#define OPT_U_DEF 2000
#define OPT_O_ELAPSED 0
#define OPT_O_JITTER 1
#define OPT_O_SUMJITTER 2
#define OPT_O_DEVIATION 3
#define OPT_O_DEVIATION_MAX 256
#define OPT_C_MIN 100
#define OPT_C_MAX 2000000000
#define OPT_C_DEF 1000
#define TIME_OUT_PERIOD 5000000
#define MILLION 1000000
#define BILLION 1000000000
int opt_o_min = OPT_O_ELAPSED;
int opt_o_max = OPT_O_SUMJITTER;
int opt_r = OPT_R_DEF;
unsigned int opt_u = OPT_U_DEF;
int opt_o = OPT_O_JITTER;
int opt_c = OPT_C_DEF;
int editOutput = 0;
volatile unsigned int elapsedTime, jitter;
struct timespec thisTime, lastTime, timeOutStart, timeOutTest;
volatile unsigned int sampleFlag = 0;
volatile int eventCounter, sumJitter, firstTime, secondTime;
void alarmWakeup(int sig_num);
void startTimer(int r, unsigned int u);
void handler(int sig_num);
char filename [100];
struct tm *timenow;
void usage()
{
fprintf
(stderr,
"\n" \
"Usage: sudo ./timerTest ... [OPTION] ...\n" \
" -r value, sets the allowed lag between alarm and callback default: %d\n"
" -u value, sets microsecond alarm setting default: %d\n" \
" %d < VALID < %d ONLY (under test)\n"\
" -o value, sets the output type default: %d\n"\
" %d elapsed time in microseconds\n"\
" %d jitter (elapsed time / -u value)\n"\
" %d cumulative jitter (jitter + jitter)\n"\
" -t value, sets duration of test cycles in event counter default: %d\n"\
" %d < VALID < %d ONLY (under test)\n"\
"\n",
OPT_R_DEF,OPT_U_DEF, OPT_U_MIN, OPT_U_MAX, OPT_O_JITTER,
OPT_O_ELAPSED, OPT_O_JITTER, OPT_O_SUMJITTER, OPT_O_DEVIATION,
OPT_O_DEVIATION_MAX, OPT_C_DEF, OPT_C_MIN, OPT_C_MAX
);
}
void fatal(int show_usage, char *fmt, ...)
{
char buf[128];
va_list ap;
va_start(ap, fmt);
vsnprintf(buf, sizeof(buf), fmt, ap);
va_end(ap);
fprintf(stderr, "%s\n", buf);
if (show_usage) usage();
fflush(stderr);
exit(EXIT_FAILURE);
}
static int initOpts(int argc, char *argv[])
{
int i, opt;
unsigned int u;
while ((opt = getopt(argc, argv, "r:u:o:t:")) != -1)
{
i = -1;
switch (opt)
{
case 'r':
i = atoi(optarg);
if ((i >= OPT_R_MIN) && (i <= OPT_R_MAX))
opt_r = i;
else fatal(1, "invalid -r option (%d)", i);
break;
case 'u':
u = atol(optarg);
if ((u >= OPT_U_MIN) && (u <= OPT_U_MAX))
opt_u = u;
else fatal(1, "invalid -u option (%d)", u);
break;
case 'o':
i = atoi(optarg);
opt_o = i; // probably fatal
break;
case 't':
i = atoi(optarg);
opt_c = i; // probably fatal
break;
default: /* '?' */
usage();
}
}
return optind;
}
int main(int argc, char *argv[])
{
int settings = 0;
// command line settings
settings = initOpts(argc, argv);
time_t now = time(NULL);
timenow = gmtime(&now);
// FILE *data;
// strftime(filename, sizeof(filename),
// "/home/pi/Documents/_C_/WiringPiAlarm/protoPulse_%Y-%m-%d_%H:%M:%S.dat", timenow);
// data = fopen(filename, "w+");
// fprintf(data,"# Sample count: %d option(s)\n", opt_c);
// fprintf(data,"# Running with %d latency at %duS sample rate\n",opt_r,opt_u);
// fprintf(data,"# Output Type is %d\n\n" , opt_o);
printf("User selects %d option(s)\n", settings-1);
printf("Running with %d latency at %duS sample rate\n",opt_r,opt_u);
printf("Output Type is %d\n" , opt_o);
printf(" Use -o value to select output type\n");
printf(" 0: elapsed time between interrutps\n");
printf(" 1: jitter (elapsed time / -u)\n");
printf(" 2: cumulative jitter (jitter + jitter)\n");
printf("Sample count: %d\n", opt_c);
printf("Starting alarm timer for %dmS...\n", opt_u);
eventCounter = 0;
firstTime = secondTime = 1;
clock_gettime(CLOCK_MONOTONIC, &lastTime);
// lastTime = micros();
timeOutStart = lastTime;
startTimer(opt_r, opt_u);
while(1)
{
if(sampleFlag){
sampleFlag = 0;
timeOutStart = lastTime;
int metaDataOutput;
switch(opt_o){ // ALL OUTPUTS DISCARD THE FIRST CALLBACK
case OPT_O_JITTER:
metaDataOutput = jitter;
break;
case OPT_O_SUMJITTER:
metaDataOutput = sumJitter;
break;
default:
metaDataOutput = elapsedTime;
break;
}
printf("%d\t%d\t%d\t%d\n",eventCounter,elapsedTime,jitter, sumJitter);
// fprintf(data,"%d\t%d\n",eventCounter,metaDataOutput);
}
clock_gettime(CLOCK_MONOTONIC, &timeOutTest);
if((MILLION * (timeOutTest.tv_sec - timeOutStart.tv_sec) + timeOutTest.tv_nsec - timeOutStart.tv_nsec)/1000>TIME_OUT_PERIOD){
fatal(0,"program timed out",0);
}
if(eventCounter >= opt_c){
fatal(0,"counted %d events", eventCounter, 0);
}
}
return 0;
}//int main(int argc, char *argv[])
void startTimer(int r, unsigned int u){
int latency = r;
unsigned int micros = u;
signal(SIGALRM, alarmWakeup);
ualarm(latency, micros);
}
void alarmWakeup(int sig_num)
{
if(sig_num == SIGALRM)
{
clock_gettime(CLOCK_MONOTONIC, &thisTime);
// thisTime = micros();
elapsedTime = (MILLION * (thisTime.tv_sec - lastTime.tv_sec) + thisTime.tv_nsec - lastTime.tv_nsec)/1000;
lastTime = thisTime;
if(firstTime){
firstTime = 0;
return;
}
if(secondTime){
secondTime = 0;
return;
}
jitter = elapsedTime - opt_u;
sumJitter += jitter;
eventCounter++;
sampleFlag = 1;
}
}
这是我得到的数据样本
User selects 0 option(s)
Running with 100 latency at 2000uS sample rate
Output Type is 1
Use -o value to select output type
0: elapsed time between interrutps
1: jitter (elapsed time / -u)
2: cumulative jitter (jitter + jitter)
Sample count: 1000
Starting alarm timer for 2000mS...
1 1928 -72 -72
2 2031 31 -41
3 1989 -11 -52
4 1975 -25 -77
5 2032 32 -45
6 1971 -29 -74
7 2027 27 -47
8 2012 12 -35
9 2051 51 16
10 1920 -80 -64
11 1998 -2 -66
12 1994 -6 -72
13 2027 27 -45
14 1998 -2 -47
15 2000 0 -47
16 1986 -14 -61
17 1906 -94 -155
18 2126 126 -29
19 1978 -22 -51
20 2047 47 -4
21 1924 -76 -80
22 2038 38 -42
23 1963 -37 -79
24 2045 45 -34
25 1863 -137 -171
26 2169 169 -2
27 1921 -79 -81
28 2040 40 -41
29 1997 -3 -44
30 2021 21 -23
31 1995 -5 -28
32 1984 -16 -44
33 1927 -73 -117
34 2059 59 -58
35 1990 -10 -68
36 1963 -37 -105
37 1836 -164 -269
38 2250 250 -19
39 1978 -22 -41
40 1962 -38 -79
41 1898 -102 -181
42 2124 124 -57
43 1997 -3 -60
44 2009 9 -51
45 2019 19 -32
46 1986 -14 -46
47 2006 6 -40
48 1999 -1 -41
49 1985 -15 -56
50 2013 13 -43
51 2001 1 -42
52 2000 0 -42
53 2169 169 127
54 1815 -185 -58
55 2007 7 -51
56 1990 -10 -61
57 1783 -217 -278
58 2269 269 -9
59 1964 -36 -45
60 2020 20 -25
61 2021 21 -4
62 1992 -8 -12
63 1996 -4 -16
64 1937 -63 -79
65 2009 9 -70
66 2061 61 -9
67 1731 -269 -278
68 2271 271 -7
69 1993 -7 -14
70 1958 -42 -56
71 1769 -231 -287
72 2303 303 16
73 1931 -69 -53
74 1810 -190 -243
75 1998 -2 -245
76 2221 221 -24
77 1998 -2 -26
78 1955 -45 -71
79 2150 150 79
80 1895 -105 -26
81 2013 13 -13
82 1852 -148 -161
83 2116 116 -45
84 1979 -21 -66
85 2004 4 -62
86 1902 -98 -160
87 1981 -19 -179
88 2203 203 24
89 1955 -45 -21
90 1970 -30 -51
91 1832 -168 -219
92 1939 -61 -280
93 2326 326 46
94 1940 -60 -14
95 2000 0 -14
96 1988 -12 -26
97 1979 -21 -47
98 2020 20 -27
99 1859 -141 -168
100 2113 113 -55
101 2028 28 -27
102 1958 -42 -69
103 1922 -78 -147
104 2134 134 -13
105 1969 -31 -44
106 2049 49 5
107 1846 -154 -149
108 2127 127 -22
109 2019 19 -3
110 1985 -15 -18
111 1994 -6 -24
112 2017 17 -7
113 1975 -25 -32
114 1957 -43 -75
115 2057 57 -18
116 1981 -19 -37
117 2011 11 -26
118 1760 -240 -266
119 2226 226 -40
120 1969 -31 -71
121 2011 11 -60
122 2293 293 233
123 1719 -281 -48
124 1980 -20 -68
125 2053 53 -15
126 1992 -8 -23
127 1955 -45 -68
128 2064 64 -4
129 1951 -49 -53
130 2045 45 -8
131 1931 -69 -77
132 1861 -139 -216
133 2220 220 4
134 1980 -20 -16
135 1827 -173 -189
136 2138 138 -51
137 2010 10 -41
138 1994 -6 -47
139 2038 38 -9
140 1987 -13 -22
141 2061 61 39
142 1921 -79 -40
143 1799 -201 -241
144 2244 244 3
145 1971 -29 -26
146 1749 -251 -277
147 2239 239 -38
148 2017 17 -21
149 1994 -6 -27
150 1920 -80 -107
151 2077 77 -30
152 1944 -56 -86
153 2085 85 -1
154 1985 -15 -16
155 1981 -19 -35
156 1985 -15 -50
157 2059 59 9
158 1929 -71 -62
159 2005 5 -57
160 2035 35 -22
161 1986 -14 -36
162 1977 -23 -59
163 2000 0 -59
164 2036 36 -23
165 3912 1912 1889
166 42 -1958 -69
167 2072 72 3
168 1754 -246 -243
169 1957 -43 -286
170 2284 284 -2
171 1993 -7 -9
172 1958 -42 -51
173 2043 43 -8
174 1762 -238 -246
175 2235 235 -11
176 1965 -35 -46
177 2049 49 3
178 1992 -8 -5
179 1982 -18 -23
180 2006 6 -17
181 1968 -32 -49
182 1790 -210 -259
183 2019 19 -240
184 2194 194 -46
185 1916 -84 -130
186 2079 79 -51
187 1849 -151 -202
188 2213 213 11
189 1944 -56 -45
190 2022 22 -23
191 2001 1 -22
192 2000 0 -22
193 2003 3 -19
194 1930 -70 -89
195 2081 81 -8
196 1946 -54 -62
197 2058 58 -4
198 1997 -3 -7
199 1932 -68 -75
200 2068 68 -7
201 1929 -71 -78
202 2034 34 -44
203 2038 38 -6
204 1998 -2 -8
205 1950 -50 -58
206 1990 -10 -68
207 1880 -120 -188
208 2368 368 180
209 1825 -175 5
210 1709 -291 -286
211 2102 102 -184
212 2110 110 -74
213 2041 41 -33
214 2027 27 -6
215 1963 -37 -43
216 1841 -159 -202
217 2215 215 13
218 1800 -200 -187
219 2195 195 8
220 1984 -16 -8
221 1988 -12 -20
222 1966 -34 -54
223 2086 86 32
224 1858 -142 -110
225 2161 161 51
226 1806 -194 -143
227 2091 91 -52
228 1990 -10 -62
229 1995 -5 -67
230 1995 -5 -72
231 2039 39 -33
232 1996 -4 -37
233 2019 19 -18
234 1990 -10 -28
235 1777 -223 -251
236 2005 5 -246
237 2308 308 62
238 1903 -97 -35
239 1783 -217 -252
240 2064 64 -188
241 1943 -57 -245
242 1963 -37 -282
243 2216 216 -66
244 1889 -111 -177
245 2125 125 -52
246 1777 -223 -275
247 2306 306 31
248 1907 -93 -62
249 1991 -9 -71
250 2016 16 -55
251 1984 -16 -71
252 2002 2 -69
253 2029 29 -40
254 2027 27 -13
255 1993 -7 -20
256 2016 16 -4
257 1814 -186 -190
258 1953 -47 -237
259 2063 63 -174
260 2117 117 -57
261 1990 -10 -67
262 1863 -137 -204
263 2207 207 3
264 1987 -13 -10
265 1992 -8 -18
266 1970 -30 -48
267 2067 67 19
268 1976 -24 -5
269 1987 -13 -18
270 1963 -37 -55
271 1992 -8 -63
272 1996 -4 -67
273 2059 59 -8
274 1986 -14 -22
275 2011 11 -11
276 1956 -44 -55
277 1990 -10 -65
278 2002 2 -63
279 2051 51 -12
280 1989 -11 -23
281 1742 -258 -281
282 2297 297 16
283 1960 -40 -24
284 1902 -98 -122
285 2053 53 -69
286 1804 -196 -265
287 2025 25 -240
288 2201 201 -39
289 1992 -8 -47
290 1996 -4 -51
291 1981 -19 -70
292 1997 -3 -73
293 2005 5 -68
294 1876 -124 -192
295 2161 161 -31
296 1913 -87 -118
297 2052 52 -66
298 2027 27 -39
299 1899 -101 -140
300 2105 105 -35
301 1849 -151 -186
302 1996 -4 -190
303 2152 152 -38
304 1945 -55 -93
305 2087 87 -6
306 1979 -21 -27
307 1971 -29 -56
308 2050 50 -6
309 1988 -12 -18
310 1998 -2 -20
311 2068 68 48
312 1890 -110 -62
313 1998 -2 -64
314 1994 -6 -70
315 2000 0 -70
316 2023 23 -47
317 1987 -13 -60
318 2055 55 -5
319 1942 -58 -63
320 1901 -99 -162
321 2144 144 -18
322 2007 7 -11
323 2010 10 -1
324 1929 -71 -72
325 2063 63 -9
326 1956 -44 -53
327 1992 -8 -61
328 2028 28 -33
329 2026 26 -7
330 1976 -24 -31
331 2005 5 -26
332 1873 -127 -153
333 2126 126 -27
334 1955 -45 -72
335 2153 153 81
336 1854 -146 -65
337 1879 -121 -186
338 2140 140 -46
339 1898 -102 -148
340 2132 132 -16
341 1983 -17 -33
342 1998 -2 -35
343 2022 22 -13
344 1942 -58 -71
345 1893 -107 -178
346 2171 171 -7
347 2067 67 60
348 1905 -95 -35
349 1867 -133 -168
350 1941 -59 -227
351 2240 240 13
352 1972 -28 -15
353 1966 -34 -49
354 2044 44 -5
355 1958 -42 -47
356 1981 -19 -66
357 -997000 -999000 -999066
358 1997 -3 -999069
359 1999 -1 -999070
360 2011 11 -999059
361 2057 57 -999002
362 1987 -13 -999015
363 1971 -29 -999044
364 2037 37 -999007
365 1845 -155 -999162
366 2173 173 -998989
367 1986 -14 -999003
368 1974 -26 -999029
369 2016 16 -999013
370 1998 -2 -999015
371 2009 9 -999006
372 1822 -178 -999184
373 1939 -61 -999245
374 2206 206 -999039
375 1923 -77 -999116
376 1917 -83 -999199
377 2202 202 -998997
378 1929 -71 -999068
379 1882 -118 -999186
380 2191 191 -998995
381 1918 -82 -999077
382 2037 37 -999040
383 2025 25 -999015
384 1917 -83 -999098
385 2052 52 -999046
386 1799 -201 -999247
387 2202 202 -999045
388 2013 13 -999032
389 1964 -36 -999068
390 2023 23 -999045
391 2050 50 -998995
392 1924 -76 -999071
393 2043 43 -999028
394 2027 27 -999001
395 1986 -14 -999015
396 1983 -17 -999032
397 1855 -145 -999177
398 2133 133 -999044
399 1976 -24 -999068
400 1781 -219 -999287
401 2179 179 -999108
402 1966 -34 -999142
403 2086 86 -999056
404 2047 47 -999009
405 2002 2 -999007
406 1971 -29 -999036
407 1995 -5 -999041
408 2041 41 -999000
409 1989 -11 -999011
410 2011 11 -999000
411 1985 -15 -999015
412 1949 -51 -999066
413 2061 61 -999005
414 1982 -18 -999023
415 1997 -3 -999026
416 2012 12 -999014
417 1979 -21 -999035
418 2029 29 -999006
419 1978 -22 -999028
420 1978 -22 -999050
421 1993 -7 -999057
422 1834 -166 -999223
423 1970 -30 -999253
424 2146 146 -999107
425 2100 100 -999007
426 1962 -38 -999045
427 1908 -92 -999137
428 2155 155 -998982
429 1753 -247 -999229
430 2198 198 -999031
431 2025 25 -999006
432 1827 -173 -999179
433 2152 152 -999027
434 2033 33 -998994
435 1880 -120 -999114
436 1898 -102 -999216
437 2225 225 -998991
438 1985 -15 -999006
439 1870 -130 -999136
440 2101 101 -999035
441 1968 -32 -999067
442 2040 40 -999027
443 1956 -44 -999071
444 2008 8 -999063
445 2046 46 -999017
446 1946 -54 -999071
447 2029 29 -999042
448 2029 29 -999013
449 1996 -4 -999017
450 2002 2 -999015
451 1976 -24 -999039
452 1972 -28 -999067
453 2031 31 -999036
454 2009 9 -999027
455 2024 24 -999003
456 1987 -13 -999016
457 2000 0 -999016
458 1851 -149 -999165
459 2167 167 -998998
460 1933 -67 -999065
461 2029 29 -999036
462 1982 -18 -999054
463 1989 -11 -999065
464 2001 1 -999064
465 1994 -6 -999070
466 2058 58 -999012
467 1993 -7 -999019
468 1945 -55 -999074
469 2011 11 -999063
470 2020 20 -999043
471 2030 30 -999013
472 2002 2 -999011
473 1729 -271 -999282
474 2217 217 -999065
475 2015 15 -999050
476 2078 78 -998972
477 2003 3 -998969
478 1937 -63 -999032
479 1963 -37 -999069
480 2050 50 -999019
481 2030 30 -998989
482 1948 -52 -999041
483 1991 -9 -999050
484 2195 195 -998855
485 1790 -210 -999065
486 1993 -7 -999072
487 2005 5 -999067
488 2064 64 -999003
489 1970 -30 -999033
490 1921 -79 -999112
491 2100 100 -999012
492 1975 -25 -999037
493 2060 60 -998977
494 1790 -210 -999187
495 1985 -15 -999202
496 2217 217 -998985
497 1829 -171 -999156
498 2167 167 -998989
499 1823 -177 -999166
500 2151 151 -999015
501 2032 32 -998983
502 1991 -9 -998992
503 1984 -16 -999008
504 1817 -183 -999191
505 2156 156 -999035
506 1963 -37 -999072
507 2013 13 -999059
508 1835 -165 -999224
509 2230 230 -998994
510 1966 -34 -999028
511 1949 -51 -999079
512 2012 12 -999067
513 2064 64 -999003
514 1780 -220 -999223
515 2173 173 -999050
516 1972 -28 -999078
517 2048 48 -999030
518 1991 -9 -999039
519 2072 72 -998967
520 1931 -69 -999036
521 2031 31 -999005
522 1991 -9 -999014
523 2005 5 -999009
524 1995 -5 -999014
525 1994 -6 -999020
526 1957 -43 -999063
527 1833 -167 -999230
528 2186 186 -999044
529 1973 -27 -999071
530 2005 5 -999066
531 2053 53 -999013
532 1970 -30 -999043
533 1891 -109 -999152
534 2086 86 -999066
535 2005 5 -999061
536 2054 54 -999007
537 1872 -128 -999135
538 2141 141 -998994
539 1991 -9 -999003
540 1729 -271 -999274
541 2284 284 -998990
542 1984 -16 -999006
543 1932 -68 -999074
544 2060 60 -999014
545 1819 -181 -999195
546 2201 201 -998994
547 1927 -73 -999067
548 2034 34 -999033
549 1774 -226 -999259
550 2219 219 -999040
551 1973 -27 -999067
552 1997 -3 -999070
553 1875 -125 -999195
554 2167 167 -999028
555 2013 13 -999015
556 1997 -3 -999018
557 1860 -140 -999158
558 2162 162 -998996
559 1792 -208 -999204
560 2004 4 -999200
561 2015 15 -999185
562 2194 194 -998991
563 1971 -29 -999020
564 1987 -13 -999033
565 1997 -3 -999036
566 1998 -2 -999038
567 2030 30 -999008
568 1769 -231 -999239
569 2259 259 -998980
570 1767 -233 -999213
571 2000 0 -999213
572 2168 168 -999045
573 1978 -22 -999067
574 1810 -190 -999257
575 2218 218 -999039
576 2039 39 -999000
577 1933 -67 -999067
578 2027 27 -999040
579 2022 22 -999018
580 2011 11 -999007
581 1997 -3 -999010
582 1845 -155 -999165
583 2152 152 -999013
584 2020 20 -998993
585 1818 -182 -999175
586 1980 -20 -999195
587 2084 84 -999111
588 1920 -80 -999191
589 2178 178 -999013
590 1998 -2 -999015
591 1930 -70 -999085
592 2038 38 -999047
593 1909 -91 -999138
594 2079 79 -999059
595 1992 -8 -999067
596 2006 6 -999061
597 1996 -4 -999065
598 2046 46 -999019
599 2011 11 -999008
600 1999 -1 -999009
601 2000 0 -999009
602 1907 -93 -999102
603 2103 103 -998999
604 1984 -16 -999015
605 1988 -12 -999027
606 2019 19 -999008
607 1985 -15 -999023
608 1952 -48 -999071
609 2045 45 -999026
610 1992 -8 -999034
611 2014 14 -999020
612 2014 14 -999006
613 1750 -250 -999256
614 2271 271 -998985
615 1959 -41 -999026
616 1958 -42 -999068
617 1997 -3 -999071
618 2011 11 -999060
619 1974 -26 -999086
620 2058 58 -999028
621 1965 -35 -999063
622 2105 105 -998958
623 1889 -111 -999069
624 2071 71 -998998
625 1989 -11 -999009
626 1734 -266 -999275
627 2307 307 -998968
628 1943 -57 -999025
629 2156 156 -998869
630 1872 -128 -998997
631 1985 -15 -999012
632 1848 -152 -999164
633 2167 167 -998997
634 1960 -40 -999037
635 2012 12 -999025
636 1737 -263 -999288
637 2256 256 -999032
638 1968 -32 -999064
639 2047 47 -999017
640 1983 -17 -999034
641 1791 -209 -999243
642 2251 251 -998992
643 1973 -27 -999019
644 1954 -46 -999065
645 1864 -136 -999201
646 2169 169 -999032
647 1969 -31 -999063
648 2023 23 -999040
649 2031 31 -999009
650 1988 -12 -999021
651 2027 27 -998994
652 1998 -2 -998996
653 1988 -12 -999008
654 1954 -46 -999054
655 2046 46 -999008
656 1997 -3 -999011
657 1955 -45 -999056
658 1880 -120 -999176
659 2153 153 -999023
660 2463 463 -998560
661 1500 -500 -999060
662 2067 67 -998993
663 2010 10 -998983
664 1940 -60 -999043
665 1778 -222 -999265
666 2220 220 -999045
667 1789 -211 -999256
668 2233 233 -999023
669 1964 -36 -999059
670 1899 -101 -999160
671 2175 175 -998985
672 1962 -38 -999023
673 2016 16 -999007
674 1894 -106 -999113
675 2118 118 -998995
676 1984 -16 -999011
677 2008 8 -999003
678 1972 -28 -999031
679 1963 -37 -999068
680 2001 1 -999067
681 1869 -131 -999198
682 2090 90 -999108
683 2072 72 -999036
684 1782 -218 -999254
685 2276 276 -998978
686 1702 -298 -999276
687 2302 302 -998974
688 1936 -64 -999038
689 2034 34 -999004
690 1988 -12 -999016
691 1963 -37 -999053
692 2048 48 -999005
693 1973 -27 -999032
694 2022 22 -999010
695 1984 -16 -999026
696 2022 22 -999004
697 1989 -11 -999015
698 2134 134 -998881
699 1820 -180 -999061
700 1996 -4 -999065
701 2002 2 -999063
702 1999 -1 -999064
703 1830 -170 -999234
704 2061 61 -999173
705 2158 158 -999015
706 1997 -3 -999018
707 1827 -173 -999191
708 1938 -62 -999253
709 2277 277 -998976
710 1990 -10 -998986
711 1720 -280 -999266
712 2293 293 -998973
713 1960 -40 -999013
714 2002 2 -999011
715 1886 -114 -999125
716 2154 154 -998971
717 1956 -44 -999015
718 2010 10 -999005
719 1841 -159 -999164
720 2175 175 -998989
721 1728 -272 -999261
722 2218 218 -999043
723 1985 -15 -999058
724 1867 -133 -999191
725 1948 -52 -999243
726 2257 257 -998986
727 1865 -135 -999121
728 2065 65 -999056
729 2049 49 -999007
730 1955 -45 -999052
731 2046 46 -999006
732 2003 3 -999003
733 1744 -256 -999259
734 2281 281 -998978
735 1992 -8 -998986
736 1922 -78 -999064
737 2055 55 -999009
738 1999 -1 -999010
739 1807 -193 -999203
740 2158 158 -999045
741 1901 -99 -999144
742 1971 -29 -999173
743 2128 128 -999045
744 1975 -25 -999070
745 2015 15 -999055
746 2041 41 -999014
747 1986 -14 -999028
748 1959 -41 -999069
749 2073 73 -998996
750 1941 -59 -999055
751 2080 80 -998975
752 1907 -93 -999068
753 2045 45 -999023
754 1851 -149 -999172
755 2200 200 -998972
756 1953 -47 -999019
757 1840 -160 -999179
758 2190 190 -998989
759 1732 -268 -999257
760 2295 295 -998962
761 1952 -48 -999010
762 1998 -2 -999012
763 1966 -34 -999046
764 1993 -7 -999053
765 1992 -8 -999061
766 1994 -6 -999067
767 1892 -108 -999175
768 2180 180 -998995
769 1718 -282 -999277
770 2262 262 -999015
771 2023 23 -998992
772 1981 -19 -999011
773 1894 -106 -999117
774 2122 122 -998995
775 1965 -35 -999030
776 2033 33 -998997
777 1936 -64 -999061
778 2056 56 -999005
779 1750 -250 -999255
780 2274 274 -998981
781 1959 -41 -999022
782 2015 15 -999007
783 1997 -3 -999010
784 1993 -7 -999017
785 1810 -190 -999207
786 2042 42 -999165
787 1912 -88 -999253
788 2214 214 -999039
789 1827 -173 -999212
790 2096 96 -999116
791 2127 127 -998989
792 1919 -81 -999070
793 2056 56 -999014
794 1953 -47 -999061
795 2052 52 -999009
796 1980 -20 -999029
797 2026 26 -999003
798 2003 3 -999000
799 1725 -275 -999275
800 2277 277 -998998
801 1952 -48 -999046
802 1906 -94 -999140
803 2141 141 -998999
804 1984 -16 -999015
805 2009 9 -999006
806 2007 7 -998999
807 1945 -55 -999054
808 1992 -8 -999062
809 1997 -3 -999065
810 1998 -2 -999067
811 2012 12 -999055
812 2038 38 -999017
813 1947 -53 -999070
814 2060 60 -999010
815 1999 -1 -999011
816 1990 -10 -999021
817 1999 -1 -999022
818 2035 35 -998987
819 1951 -49 -999036
820 1978 -22 -999058
821 2018 18 -999040
822 2014 14 -999026
823 2019 19 -999007
824 1982 -18 -999025
825 2017 17 -999008
826 2029 29 -998979
827 1980 -20 -998999
828 1941 -59 -999058
829 2017 17 -999041
830 1979 -21 -999062
831 1894 -106 -999168
832 1914 -86 -999254
833 2239 239 -999015
834 2003 3 -999012
835 1897 -103 -999115
836 1935 -65 -999180
837 2193 193 -998987
838 1982 -18 -999005
839 1987 -13 -999018
840 1946 -54 -999072
841 2070 70 -999002
842 1893 -107 -999109
843 1946 -54 -999163
844 2176 176 -998987
845 1973 -27 -999014
846 2002 2 -999012
847 1990 -10 -999022
848 2015 15 -999007
849 2003 3 -999004
850 1742 -258 -999262
851 2412 412 -998850
852 1782 -218 -999068
853 2034 34 -999034
854 1970 -30 -999064
855 2033 33 -999031
856 1996 -4 -999035
857 -996970 -998970 -1998005
858 1957 -43 -1998048
859 1871 -129 -1998177
860 2142 142 -1998035
861 1796 -204 -1998239
862 2287 287 -1997952
863 1924 -76 -1998028
864 2019 19 -1998009
865 2063 63 -1997946
866 1935 -65 -1998011
867 1999 -1 -1998012
868 2007 7 -1998005
869 1996 -4 -1998009
870 1984 -16 -1998025
871 1957 -43 -1998068
872 2037 37 -1998031
873 1763 -237 -1998268
874 2242 242 -1998026
875 1961 -39 -1998065
876 2020 20 -1998045
877 1984 -16 -1998061
878 2062 62 -1997999
879 1980 -20 -1998019
880 1754 -246 -1998265
881 2284 284 -1997981
882 1836 -164 -1998145
883 2221 221 -1997924
884 1936 -64 -1997988
885 1978 -22 -1998010
886 1853 -147 -1998157
887 2146 146 -1998011
888 2005 5 -1998006
889 1993 -7 -1998013
890 1866 -134 -1998147
891 2164 164 -1997983
892 1742 -258 -1998241
893 2147 147 -1998094
894 2081 81 -1998013
895 1955 -45 -1998058
896 1997 -3 -1998061
897 2054 54 -1998007
898 1964 -36 -1998043
899 2032 32 -1998011
900 1999 -1 -1998012
901 1996 -4 -1998016
902 1988 -12 -1998028
903 1836 -164 -1998192
904 2212 212 -1997980
905 2033 33 -1997947
906 1825 -175 -1998122
907 2142 142 -1997980
908 1983 -17 -1997997
909 1925 -75 -1998072
910 2075 75 -1997997
911 1995 -5 -1998002
912 1759 -241 -1998243
913 2268 268 -1997975
914 1828 -172 -1998147
915 2101 101 -1998046
916 1894 -106 -1998152
917 2115 115 -1998037
918 1993 -7 -1998044
919 1934 -66 -1998110
920 2100 100 -1998010
921 1995 -5 -1998015
922 1980 -20 -1998035
923 2110 110 -1997925
924 1945 -55 -1997980
925 1731 -269 -1998249
926 2305 305 -1997944
927 1870 -130 -1998074
928 1904 -96 -1998170
929 2179 179 -1997991
930 1894 -106 -1998097
931 2090 90 -1998007
932 2225 225 -1997782
933 1791 -209 -1997991
934 1954 -46 -1998037
935 2010 10 -1998027
936 1754 -246 -1998273
937 2245 245 -1998028
938 1962 -38 -1998066
939 2001 1 -1998065
940 2064 64 -1998001
941 1969 -31 -1998032
942 2060 60 -1997972
943 2042 42 -1997930
944 1669 -331 -1998261
945 2292 292 -1997969
946 1959 -41 -1998010
947 2012 12 -1997998
948 1931 -69 -1998067
949 2057 57 -1998010
950 2009 9 -1998001
951 1825 -175 -1998176
952 2203 203 -1997973
953 1964 -36 -1998009
954 2077 77 -1997932
955 1941 -59 -1997991
956 1988 -12 -1998003
957 1970 -30 -1998033
958 1980 -20 -1998053
959 1992 -8 -1998061
960 2001 1 -1998060
961 2221 221 -1997839
962 1834 -166 -1998005
963 1993 -7 -1998012
964 1987 -13 -1998025
965 2026 26 -1997999
966 1987 -13 -1998012
967 2001 1 -1998011
968 2004 4 -1998007
969 1944 -56 -1998063
970 1885 -115 -1998178
971 2203 203 -1997975
972 1965 -35 -1998010
973 2049 49 -1997961
974 1967 -33 -1997994
975 1784 -216 -1998210
976 2219 219 -1997991
977 1976 -24 -1998015
978 1973 -27 -1998042
979 2025 25 -1998017
980 1981 -19 -1998036
981 1981 -19 -1998055
982 2058 58 -1997997
983 1969 -31 -1998028
984 2023 23 -1998005
985 2006 6 -1997999
986 1810 -190 -1998189
987 2206 206 -1997983
988 1990 -10 -1997993
989 1952 -48 -1998041
990 1983 -17 -1998058
991 2033 33 -1998025
992 2000 0 -1998025
993 2011 11 -1998014
994 1864 -136 -1998150
995 1893 -107 -1998257
996 2287 287 -1997970
997 1957 -43 -1998013
998 2006 6 -1998007
999 1957 -43 -1998050
counted 1000 events
我是不是用错了 clock_gettime 函数？ 我应该使用不同的计时器吗？ 看起来像翻车。如果这被纳入定时器读取功能，有没有人知道如何解决它？
是的，我知道我正在使用 ualarm() 此代码的最终目标是树莓派。我只是在玩弄我制作的基准测试工具，并认为我可以在我的笔记本电脑上运行。我在 RPi 上没有遇到类似的问题……虽然我一次运行它的时间不超过 ~10 秒……
最佳答案
尽管这对生产代码来说是不好的做法，但我还是在信号处理程序中添加了一个 printf() 语句来记录输出:
/* SO 5538-7600 */
#include "time_math.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <signal.h>
#include <unistd.h>
#include <time.h>
#define OPT_R_MIN 0
#define OPT_R_MAX 5000
#define OPT_R_DEF 100
#define OPT_U_MIN 100
#define OPT_U_MAX 2000000000 // 2K seconds
#define OPT_U_DEF 2000
#define OPT_O_ELAPSED 0
#define OPT_O_JITTER 1
#define OPT_O_SUMJITTER 2
#define OPT_O_DEVIATION 3
#define OPT_O_DEVIATION_MAX 256
#define OPT_C_MIN 100
#define OPT_C_MAX 2000000000
#define OPT_C_DEF 1000
#define TIME_OUT_PERIOD 5000000
#define MILLION 1000000
#define BILLION 1000000000
int opt_o_min = OPT_O_ELAPSED;
int opt_o_max = OPT_O_SUMJITTER;
int opt_r = OPT_R_DEF;
unsigned int opt_u = OPT_U_DEF;
int opt_o = OPT_O_JITTER;
int opt_c = OPT_C_DEF;
int editOutput = 0;
volatile unsigned int elapsedTime, jitter;
struct timespec thisTime, lastTime, timeOutStart, timeOutTest;
volatile unsigned int sampleFlag = 0;
volatile int eventCounter, sumJitter, firstTime, secondTime;
void alarmWakeup(int sig_num);
void startTimer(int r, unsigned int u);
void handler(int sig_num);
char filename[100];
struct tm *timenow;
static void usage(void)
{
fprintf(stderr,
"Usage: sudo ./timerTest ... [OPTION] ...\n"
" -r value, sets the allowed lag between alarm and callback default: %d\n"
" -u value, sets microsecond alarm setting default: %d\n"
" %d < VALID < %d ONLY (under test)\n"
" -o value, sets the output type default: %d\n"
" %d elapsed time in microseconds\n"
" %d jitter (elapsed time / -u value)\n"
" %d cumulative jitter (jitter + jitter)\n"
" -t value, sets duration of test cycles in event counter default: %d\n"
" %d < VALID < %d ONLY (under test)\n"
"\n",
OPT_R_DEF, OPT_U_DEF, OPT_U_MIN, OPT_U_MAX, OPT_O_JITTER,
OPT_O_ELAPSED, OPT_O_JITTER, OPT_O_SUMJITTER, OPT_O_DEVIATION,
OPT_O_DEVIATION_MAX, OPT_C_DEF//, OPT_C_MIN, OPT_C_MAX
);
}
static void fatal(int show_usage, char *fmt, ...)
{
char buf[128];
va_list ap;
va_start(ap, fmt);
vsnprintf(buf, sizeof(buf), fmt, ap);
va_end(ap);
fprintf(stderr, "%s\n", buf);
if (show_usage)
usage();
fflush(stderr);
exit(EXIT_FAILURE);
}
static int initOpts(int argc, char *argv[])
{
int i, opt;
unsigned int u;
while ((opt = getopt(argc, argv, "r:u:o:t:")) != -1)
{
i = -1;
switch (opt)
{
case 'r':
i = atoi(optarg);
if ((i >= OPT_R_MIN) && (i <= OPT_R_MAX))
opt_r = i;
else
fatal(1, "invalid -r option (%d)", i);
break;
case 'u':
u = atol(optarg);
if ((u >= OPT_U_MIN) && (u <= OPT_U_MAX))
opt_u = u;
else
fatal(1, "invalid -u option (%d)", u);
break;
case 'o':
i = atoi(optarg);
opt_o = i; // probably fatal
break;
case 't':
i = atoi(optarg);
opt_c = i; // probably fatal
break;
default: /* '?' */
usage();
}
}
return optind;
}
int main(int argc, char *argv[])
{
int settings = 0;
// command line settings
settings = initOpts(argc, argv);
time_t now = time(NULL);
timenow = gmtime(&now);
// FILE *data;
// strftime(filename, sizeof(filename),
// "/home/pi/Documents/_C_/WiringPiAlarm/protoPulse_%Y-%m-%d_%H:%M:%S.dat", timenow);
// data = fopen(filename, "w+");
// fprintf(data,"# Sample count: %d option(s)\n", opt_c);
// fprintf(data,"# Running with %d latency at %duS sample rate\n",opt_r,opt_u);
// fprintf(data,"# Output Type is %d\n\n" , opt_o);
printf("User selects %d option(s)\n", settings - 1);
printf("Running with %d latency at %duS sample rate\n", opt_r, opt_u);
printf("Output Type is %d\n", opt_o);
printf(" Use -o value to select output type\n");
printf(" 0: elapsed time between interrutps\n");
printf(" 1: jitter (elapsed time / -u)\n");
printf(" 2: cumulative jitter (jitter + jitter)\n");
printf("Sample count: %d\n", opt_c);
printf("Starting alarm timer for %dmS...\n", opt_u);
eventCounter = 0;
firstTime = secondTime = 1;
clock_gettime(CLOCK_MONOTONIC, &lastTime);
// lastTime = micros();
timeOutStart = lastTime;
startTimer(opt_r, opt_u);
while (1)
{
if (sampleFlag)
{
sampleFlag = 0;
timeOutStart = lastTime;
// int metaDataOutput;
// switch(opt_o){ // ALL OUTPUTS DISCARD THE FIRST CALLBACK
// case OPT_O_JITTER:
// metaDataOutput = jitter;
// break;
// case OPT_O_SUMJITTER:
// metaDataOutput = sumJitter;
// break;
// default:
// metaDataOutput = elapsedTime;
// break;
// }
printf("%d\t%d\t%d\t%d\n", eventCounter, elapsedTime, jitter, sumJitter);
// fprintf(data,"%d\t%d\n",eventCounter,metaDataOutput);
}
clock_gettime(CLOCK_MONOTONIC, &timeOutTest);
if ((MILLION * (timeOutTest.tv_sec - timeOutStart.tv_sec) + timeOutTest.tv_nsec - timeOutStart.tv_nsec) / 1000 > TIME_OUT_PERIOD)
{
fatal(0, "program timed out", 0);
}
if (eventCounter >= opt_c)
{
fatal(0, "counted %d events", eventCounter, 0);
}
}
return 0;
}
void startTimer(int r, unsigned int u)
{
int latency = r;
unsigned int micros = u;
signal(SIGALRM, alarmWakeup);
ualarm(latency, micros);
}
void alarmWakeup(int sig_num)
{
if (sig_num == SIGALRM)
{
clock_gettime(CLOCK_MONOTONIC, &thisTime);
// thisTime = micros();
elapsedTime = (MILLION * (thisTime.tv_sec - lastTime.tv_sec) + thisTime.tv_nsec - lastTime.tv_nsec) / 1000;
struct timespec diff;
sub_timespec(lastTime, thisTime, &diff);
/* Not good practice! */
printf("%10u : %ld.%.9ld - %ld.%.9ld (%ld.%.9ld) - ",
elapsedTime,
thisTime.tv_sec, thisTime.tv_nsec,
lastTime.tv_sec, lastTime.tv_nsec,
diff.tv_sec, diff.tv_nsec);
lastTime = thisTime;
if (firstTime)
{
firstTime = 0;
return;
}
if (secondTime)
{
secondTime = 0;
return;
}
jitter = elapsedTime - opt_u;
sumJitter += jitter;
eventCounter++;
sampleFlag = 1;
}
}
time_math.h header 包含:
#include <time.h>
extern void sub_timespec(struct timespec t1, struct timespec t2, struct timespec *td);
而 sub_timespec() 代码是(如评论中所示):
enum { NS_PER_SECOND = 1000000000 };
void sub_timespec(struct timespec t1, struct timespec t2, struct timespec *td)
{
td->tv_nsec = t2.tv_nsec - t1.tv_nsec;
td->tv_sec = t2.tv_sec - t1.tv_sec;
if (td->tv_sec > 0 && td->tv_nsec < 0)
{
td->tv_nsec += NS_PER_SECOND;
td->tv_sec--;
}
else if (td->tv_sec < 0 && td->tv_nsec > 0)
{
td->tv_nsec -= NS_PER_SECOND;
td->tv_sec++;
}
}
在问题的尖端，输出是:
1896 : 169978.995568000 - 169978.993672000 (0.001896000) - 97 1896 -104 64
1978 : 169978.997546000 - 169978.995568000 (0.001978000) - 98 1978 -22 42
2136 : 169978.999682000 - 169978.997546000 (0.002136000) - 99 2136 136 178
4293970278 : 169979.001664000 - 169978.999682000 (0.001982000) - 100 -997018 -999018 -998840
2019 : 169979.003683000 - 169979.001664000 (0.002019000) - 101 2019 19 -998821
2041 : 169979.005724000 - 169979.003683000 (0.002041000) - 102 2041 41 -998780
如您所见，当 tv_nsec 值从 999418000 翻转到 001406000 时，数字完全失控。 (在 macOS 上，尽管 clock_gettime() 报告的是纳秒，但最后三位数字始终为零，因此它实际上报告的是微秒。)您可能还会看到，括号中的数字( 的输出sub_timespec()) 在那一点上不会失控。
关于clock_gettime 每秒都会出现故障，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/55387600/