tools/testing/selftests/timers/nsleep-lat.c

   1 /* Measure nanosleep timer latency
   2  *              by: john stultz (john.stultz@linaro.org)
   3  *              (C) Copyright Linaro 2013
   4  *              Licensed under the GPLv2
   5  *
   6  *  To build:
   7  *      $ gcc nsleep-lat.c -o nsleep-lat -lrt
   8  *
   9  *   This program is free software: you can redistribute it and/or modify
  10  *   it under the terms of the GNU General Public License as published by
  11  *   the Free Software Foundation, either version 2 of the License, or
  12  *   (at your option) any later version.
  13  *
  14  *   This program is distributed in the hope that it will be useful,
  15  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  *   GNU General Public License for more details.
  18  */
  19
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <time.h>
  23 #include <sys/time.h>
  24 #include <sys/timex.h>
  25 #include <string.h>
  26 #include <signal.h>
  27 #ifdef KTEST
  28 #include "../kselftest.h"
  29 #else
  30 static inline int ksft_exit_pass(void)
  31 {
  32         exit(0);
  33 }
  34 static inline int ksft_exit_fail(void)
  35 {
  36         exit(1);
  37 }
  38 #endif
  39
  40 #define NSEC_PER_SEC 1000000000ULL
  41
  42 #define UNRESONABLE_LATENCY 40000000 /* 40ms in nanosecs */
  43
  44
  45 #define CLOCK_REALTIME                  0
  46 #define CLOCK_MONOTONIC                 1
  47 #define CLOCK_PROCESS_CPUTIME_ID        2
  48 #define CLOCK_THREAD_CPUTIME_ID         3
  49 #define CLOCK_MONOTONIC_RAW             4
  50 #define CLOCK_REALTIME_COARSE           5
  51 #define CLOCK_MONOTONIC_COARSE          6
  52 #define CLOCK_BOOTTIME                  7
  53 #define CLOCK_REALTIME_ALARM            8
  54 #define CLOCK_BOOTTIME_ALARM            9
  55 #define CLOCK_HWSPECIFIC                10
  56 #define CLOCK_TAI                       11
  57 #define NR_CLOCKIDS                     12
  58
  59 #define UNSUPPORTED 0xf00f
  60
  61 char *clockstring(int clockid)
  62 {
  63         switch (clockid) {
  64         case CLOCK_REALTIME:
  65                 return "CLOCK_REALTIME";
  66         case CLOCK_MONOTONIC:
  67                 return "CLOCK_MONOTONIC";
  68         case CLOCK_PROCESS_CPUTIME_ID:
  69                 return "CLOCK_PROCESS_CPUTIME_ID";
  70         case CLOCK_THREAD_CPUTIME_ID:
  71                 return "CLOCK_THREAD_CPUTIME_ID";
  72         case CLOCK_MONOTONIC_RAW:
  73                 return "CLOCK_MONOTONIC_RAW";
  74         case CLOCK_REALTIME_COARSE:
  75                 return "CLOCK_REALTIME_COARSE";
  76         case CLOCK_MONOTONIC_COARSE:
  77                 return "CLOCK_MONOTONIC_COARSE";
  78         case CLOCK_BOOTTIME:
  79                 return "CLOCK_BOOTTIME";
  80         case CLOCK_REALTIME_ALARM:
  81                 return "CLOCK_REALTIME_ALARM";
  82         case CLOCK_BOOTTIME_ALARM:
  83                 return "CLOCK_BOOTTIME_ALARM";
  84         case CLOCK_TAI:
  85                 return "CLOCK_TAI";
  86         };
  87         return "UNKNOWN_CLOCKID";
  88 }
  89
  90 struct timespec timespec_add(struct timespec ts, unsigned long long ns)
  91 {
  92         ts.tv_nsec += ns;
  93         while (ts.tv_nsec >= NSEC_PER_SEC) {
  94                 ts.tv_nsec -= NSEC_PER_SEC;
  95                 ts.tv_sec++;
  96         }
  97         return ts;
  98 }
  99
 100
 101 long long timespec_sub(struct timespec a, struct timespec b)
 102 {
 103         long long ret = NSEC_PER_SEC * b.tv_sec + b.tv_nsec;
 104
 105         ret -= NSEC_PER_SEC * a.tv_sec + a.tv_nsec;
 106         return ret;
 107 }
 108
 109 int nanosleep_lat_test(int clockid, long long ns)
 110 {
 111         struct timespec start, end, target;
 112         long long latency = 0;
 113         int i, count;
 114
 115         target.tv_sec = ns/NSEC_PER_SEC;
 116         target.tv_nsec = ns%NSEC_PER_SEC;
 117
 118         if (clock_gettime(clockid, &start))
 119                 return UNSUPPORTED;
 120         if (clock_nanosleep(clockid, 0, &target, NULL))
 121                 return UNSUPPORTED;
 122
 123         count = 10;
 124
 125         /* First check relative latency */
 126         clock_gettime(clockid, &start);
 127         for (i = 0; i < count; i++)
 128                 clock_nanosleep(clockid, 0, &target, NULL);
 129         clock_gettime(clockid, &end);
 130
 131         if (((timespec_sub(start, end)/count)-ns) > UNRESONABLE_LATENCY) {
 132                 printf("Large rel latency: %lld ns :", (timespec_sub(start, end)/count)-ns);
 133                 return -1;
 134         }
 135
 136         /* Next check absolute latency */
 137         for (i = 0; i < count; i++) {
 138                 clock_gettime(clockid, &start);
 139                 target = timespec_add(start, ns);
 140                 clock_nanosleep(clockid, TIMER_ABSTIME, &target, NULL);
 141                 clock_gettime(clockid, &end);
 142                 latency += timespec_sub(target, end);
 143         }
 144
 145         if (latency/count > UNRESONABLE_LATENCY) {
 146                 printf("Large abs latency: %lld ns :", latency/count);
 147                 return -1;
 148         }
 149
 150         return 0;
 151 }
 152
 153
 154
 155 int main(int argc, char **argv)
 156 {
 157         long long length;
 158         int clockid, ret;
 159
 160         for (clockid = CLOCK_REALTIME; clockid < NR_CLOCKIDS; clockid++) {
 161
 162                 /* Skip cputime clockids since nanosleep won't increment cputime */
 163                 if (clockid == CLOCK_PROCESS_CPUTIME_ID ||
 164                                 clockid == CLOCK_THREAD_CPUTIME_ID ||
 165                                 clockid == CLOCK_HWSPECIFIC)
 166                         continue;
 167
 168                 printf("nsleep latency %-26s ", clockstring(clockid));
 169
 170                 length = 10;
 171                 while (length <= (NSEC_PER_SEC * 10)) {
 172                         ret = nanosleep_lat_test(clockid, length);
 173                         if (ret)
 174                                 break;
 175                         length *= 100;
 176
 177                 }
 178
 179                 if (ret == UNSUPPORTED) {
 180                         printf("[UNSUPPORTED]\n");
 181                         continue;
 182                 }
 183                 if (ret < 0) {
 184                         printf("[FAILED]\n");
 185                         return ksft_exit_fail();
 186                 }
 187                 printf("[OK]\n");
 188         }
 189         return ksft_exit_pass();
 190 }