scheduling_jitter.c
Go to the documentation of this file.
1 /*******************************************************************************
2  * Copyright (C) 2019 Moxa Inc. All rights reserved.
3  * SPDX-License-Identifier: Apache-2.0
4  *
5  * Scheduling Jitter Sample Application
6  *
7  * Date Author Comment
8  * 2019-04-25 Wanhan Hsieh Created it.
9  ******************************************************************************/
10 
44 #include <stdio.h>
45 #include <stdlib.h>
46 #include <unistd.h>
47 #include <signal.h>
48 #include <pthread.h>
49 #include <errno.h>
50 #include <sys/time.h>
51 #include <time.h>
52 #include <iothinx/iothinxio.h>
53 #include <sched.h>
54 
55 int set_process_priority(int pid, int priority_level)
56 {
57  int rc = 0;
58  int policy;
59  struct sched_param param = { 0 };
60 
61  switch (priority_level)
62  {
63  case 1: // medium
64  policy = SCHED_RR;
65  param.sched_priority = 1;
66  break;
67  case 2: // high
68  policy = SCHED_RR;
69  param.sched_priority = 49;
70  break;
71  case 3: // max
72  policy = SCHED_RR;
73  param.sched_priority = 99;
74  break;
75  case 0: // low
76  default:
77  policy = SCHED_OTHER;
78  param.sched_priority = 0;
79  break;
80  }
81  rc = sched_setscheduler(pid, policy, &param);
82  if (rc != 0)
83  {
84  perror("sched_setscheduler");
85  }
86  return rc;
87 }
88 
90 int main(int argc, char **const argv)
91 {
92  int32_t rc;
93  uint32_t do_slot = 2;
94  uint8_t do_channel = 0;
95  uint8_t do_mode = DO_MODE_DO;
96  uint32_t do_values = 0;
97  uint32_t test_cnt = 1000;
98  uint32_t cycle_time_us = 10000;
99  uint32_t i;
100  time_t start_time_us, end_time_us;
101  time_t last_start_time_us = 0;
102  int priority_level = 3;
103  int32_t diff_us;
104  int32_t sum_us = 0;
105  int32_t max_us = 0;
106  struct timespec ts;
107 
108  while (-1 != (rc = getopt(argc, argv, "c:hn:p:s:t:")))
109  {
110  switch (rc)
111  {
112  case 'c':
113  do_channel = atoi(optarg);
114  break;
115  case 'n':
116  test_cnt = atoi(optarg);
117  break;
118  case 'p':
119  priority_level = atoi(optarg);
120  break;
121  case 's':
122  do_slot = atoi(optarg);
123  break;
124  case 't':
125  cycle_time_us = atoi(optarg);
126  break;
127  case 'h':
128  default:
129  printf("Scheduling jitter sample program.\n\n");
130  printf("Usage: ./scheduling_jitter [OPTIONS]\n\n");
131  printf("Options: \n");
132  printf("\t %-8s Priority level[0-3]. Default level = %d\n", "-p", priority_level);
133  printf("\t %-8s Slot of DO module. Default slot = %d\n", "-s", do_slot);
134  printf("\t %-8s DO channel. Default channel = %d\n", "-c", do_channel);
135  printf("\t %-8s Testing loop count. Default count = %d\n", "-n", test_cnt);
136  printf("\t %-8s Testing loop cycle time (in us). Default time = %d us\n", "-t", cycle_time_us);
137  printf("\n");
138  return 0;
139  }
140  }
141 
142  printf("Priority level = %d\n", priority_level);
143  printf("DO slot = %lu\n", do_slot);
144  printf("DO channel = %u\n", do_channel);
145 
146  // initialize ioThinx I/O
147  rc = ioThinx_IO_Client_Init();
148  if (rc != IOTHINX_ERR_OK)
149  {
150  printf("ioThinx_IO_Client_Init() = %d\n", rc);
151  return -1;
152  }
153 
154  // temporarily set config
155  rc = ioThinx_DO_Config_SetModes(do_slot, do_channel, 1, &do_mode);
156  if (rc != IOTHINX_ERR_OK)
157  {
158  printf("ioThinx_DO_Config_SetModes() = %d\n", rc);
159  return -1;
160  }
161 
162  // reload config
164  if (rc != IOTHINX_ERR_OK)
165  {
166  printf("ioThinx_IO_Config_Reload() = %d\n", rc);
167  return -1;
168  }
169 
170  // set process priority
171  set_process_priority(0, priority_level);
172  if (rc != 0)
173  {
174  return -1;
175  }
176 
177  printf("Start testing ...\n");
178 
179  for (i = 0; i < test_cnt; i++)
180  {
181  // get start time
182  clock_gettime(CLOCK_MONOTONIC, &ts);
183  start_time_us = (ts.tv_sec * 1000000 + ts.tv_nsec / 1000);
184  diff_us = (last_start_time_us == 0) ? 0 : start_time_us - last_start_time_us - cycle_time_us;
185  sum_us += diff_us;
186  max_us = (diff_us > max_us) ? diff_us : max_us;
187  last_start_time_us = start_time_us;
188 
189  // do the stuff ...
190  // invert do value
191  if (do_values & (0x1 << do_channel))
192  {
193  do_values &= ~(0x1 << do_channel);
194  }
195  else
196  {
197  do_values |= 0x1 << do_channel;
198  }
199  rc = ioThinx_DO_SetValues(do_slot, do_values);
200  if (rc != IOTHINX_ERR_OK)
201  {
202  printf("ioThinx_DO_SetValues() = %d\n", rc);
203  break;
204  }
205 
206  // get end time
207  clock_gettime(CLOCK_MONOTONIC, &ts);
208  end_time_us = (ts.tv_sec * 1000000 + ts.tv_nsec / 1000);
209 
210  // calculate sleep time
211  diff_us = cycle_time_us - (end_time_us - start_time_us);
212  ts.tv_sec = 0;
213  ts.tv_nsec = diff_us * 1000;
214 
215  // sleep
216  clock_nanosleep(CLOCK_MONOTONIC, 0, &ts, NULL);
217  }
218 
219  printf("Done.\n");
220  printf("Scheduling jitter: Avg. = %.1f us, Max = %ld us\n",
221  (float)sum_us / (float)(test_cnt - 1), max_us);
222 
223  return 0;
224 }
#define DO_MODE_DO
Definition: iothinxio.h:291
IOTHINX_ERR ioThinx_DO_SetValues(uint32_t slot, uint32_t values)
#define IOTHINX_ERR_OK
Definition: iothinxio.h:35
IOTHINX_ERR ioThinx_DO_Config_SetModes(uint32_t slot, uint8_t start, uint8_t count, uint8_t buf[])
int main(int argc, char **const argv)
IOTHINX_ERR ioThinx_IO_Config_Reload(void)
int set_process_priority(int pid, int priority_level)
IOTHINX_ERR ioThinx_IO_Client_Init(void)