103 lines
2.5 KiB
C
103 lines
2.5 KiB
C
|
/*
|
||
|
|
* delayTest.c:
|
||
|
|
* Just a little test program I'm using to experiment with
|
||
|
|
* various timings and latency, etc.
|
||
|
|
*
|
||
|
|
* Copyright (c) 2012-2013 Gordon Henderson. <projects@drogon.net>
|
||
|
|
***********************************************************************
|
||
|
|
* This file is part of wiringPi:
|
||
|
|
* https://projects.drogon.net/raspberry-pi/wiringpi/
|
||
|
|
*
|
||
|
|
* wiringPi is free software: you can redistribute it and/or modify
|
||
|
|
* it under the terms of the GNU Lesser General Public License as published by
|
||
|
|
* the Free Software Foundation, either version 3 of the License, or
|
||
|
|
* (at your option) any later version.
|
||
|
|
*
|
||
|
|
* wiringPi is distributed in the hope that it will be useful,
|
||
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
|
|
* GNU Lesser General Public License for more details.
|
||
|
|
*
|
||
|
|
* You should have received a copy of the GNU Lesser General Public License
|
||
|
|
* along with wiringPi. If not, see <http://www.gnu.org/licenses/>.
|
||
|
|
***********************************************************************
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <stdio.h>
|
||
|
|
#include <unistd.h>
|
||
|
|
|
||
|
|
#include <sys/time.h>
|
||
|
|
|
||
|
|
#define CYCLES 1000
|
||
|
|
|
||
|
|
int main()
|
||
|
|
{
|
||
|
|
int x ;
|
||
|
|
struct timeval t1, t2, t3 ;
|
||
|
|
int t ;
|
||
|
|
int max, min ;
|
||
|
|
int del ;
|
||
|
|
int underRuns, overRuns, exactRuns, bogusRuns, total ;
|
||
|
|
int descheds ;
|
||
|
|
|
||
|
|
|
||
|
|
// Baseline test
|
||
|
|
|
||
|
|
gettimeofday (&t1, NULL) ;
|
||
|
|
gettimeofday (&t2, NULL) ;
|
||
|
|
|
||
|
|
t = t2.tv_usec - t1.tv_usec ;
|
||
|
|
printf ("Baseline test: %d\n", t);
|
||
|
|
|
||
|
|
for (del = 1 ; del < 200 ; ++del)
|
||
|
|
{
|
||
|
|
underRuns = overRuns = exactRuns = total = 0 ;
|
||
|
|
descheds = 0 ;
|
||
|
|
max = 0 ;
|
||
|
|
min = 999 ;
|
||
|
|
|
||
|
|
for (x = 0 ; x < CYCLES ; ++x)
|
||
|
|
{
|
||
|
|
for (;;) // Repeat this if we get a delay over 999uS
|
||
|
|
{ // -> High probability Linux has deschedulled us
|
||
|
|
gettimeofday (&t1, NULL) ;
|
||
|
|
usleep (del) ;
|
||
|
|
// delayMicroseconds (del) ;
|
||
|
|
gettimeofday (&t2, NULL) ;
|
||
|
|
|
||
|
|
timersub (&t2, &t1, &t3) ;
|
||
|
|
|
||
|
|
t = t3.tv_usec ;
|
||
|
|
|
||
|
|
if (t > 999)
|
||
|
|
{
|
||
|
|
++descheds ;
|
||
|
|
continue ;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
break ;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (t == del)
|
||
|
|
++exactRuns ;
|
||
|
|
else if (t < del)
|
||
|
|
++underRuns ;
|
||
|
|
else if (t > del)
|
||
|
|
++overRuns ;
|
||
|
|
|
||
|
|
if (t > max)
|
||
|
|
max = t ;
|
||
|
|
else if (t < min)
|
||
|
|
min = t ;
|
||
|
|
|
||
|
|
total += t ;
|
||
|
|
}
|
||
|
|
printf ("Delay: %3d. Min: %3d, Max: %3d, Unders: %3d, Overs: %3d, Exacts: %3d, Average: %3d, Descheds: %2d\n",
|
||
|
|
del, min, max, underRuns, overRuns, exactRuns, total / CYCLES, descheds) ;
|
||
|
|
fflush (stdout) ;
|
||
|
|
usleep (1000) ;
|
||
|
|
}
|
||
|
|
|
||
|
|
return 0 ;
|
||
|
|
}
|