src/backend/utils/misc/pg_rusage.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * pg_rusage.c
   4  *        Resource usage measurement support routines.
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  *
  11  * IDENTIFICATION
  12  *        $PostgreSQL$
  13  *
  14  *-------------------------------------------------------------------------
  15  */
  16 #include "postgres.h"
  17
  18 #include <unistd.h>
  19
  20 #include "utils/pg_rusage.h"
  21
  22
  23 /*
  24  * Initialize usage snapshot.
  25  */
  26 void
  27 pg_rusage_init(PGRUsage *ru0)
  28 {
  29         getrusage(RUSAGE_SELF, &ru0->ru);
  30         gettimeofday(&ru0->tv, NULL);
  31 }
  32
  33 /*
  34  * Compute elapsed time since ru0 usage snapshot, and format into
  35  * a displayable string.  Result is in a static string, which is
  36  * tacky, but no one ever claimed that the Postgres backend is
  37  * threadable...
  38  */
  39 const char *
  40 pg_rusage_show(const PGRUsage *ru0)
  41 {
  42         static char result[100];
  43         PGRUsage        ru1;
  44
  45         pg_rusage_init(&ru1);
  46
  47         if (ru1.tv.tv_usec < ru0->tv.tv_usec)
  48         {
  49                 ru1.tv.tv_sec--;
  50                 ru1.tv.tv_usec += 1000000;
  51         }
  52         if (ru1.ru.ru_stime.tv_usec < ru0->ru.ru_stime.tv_usec)
  53         {
  54                 ru1.ru.ru_stime.tv_sec--;
  55                 ru1.ru.ru_stime.tv_usec += 1000000;
  56         }
  57         if (ru1.ru.ru_utime.tv_usec < ru0->ru.ru_utime.tv_usec)
  58         {
  59                 ru1.ru.ru_utime.tv_sec--;
  60                 ru1.ru.ru_utime.tv_usec += 1000000;
  61         }
  62
  63         snprintf(result, sizeof(result),
  64                          "CPU %d.%02ds/%d.%02du sec elapsed %d.%02d sec",
  65                          (int) (ru1.ru.ru_stime.tv_sec - ru0->ru.ru_stime.tv_sec),
  66                   (int) (ru1.ru.ru_stime.tv_usec - ru0->ru.ru_stime.tv_usec) / 10000,
  67                          (int) (ru1.ru.ru_utime.tv_sec - ru0->ru.ru_utime.tv_sec),
  68                   (int) (ru1.ru.ru_utime.tv_usec - ru0->ru.ru_utime.tv_usec) / 10000,
  69                          (int) (ru1.tv.tv_sec - ru0->tv.tv_sec),
  70                          (int) (ru1.tv.tv_usec - ru0->tv.tv_usec) / 10000);
  71
  72         return result;
  73 }