[Bug 2084] New: Incorrect clock() return value if USE_TICKS_FOR_STATISTICS=1

[bugzilla-daemon at rtems.org]

https://www.rtems.org/bugzilla/show_bug.cgi?id=2084

             Bug #: 2084
           Summary: Incorrect clock() return value if
                    USE_TICKS_FOR_STATISTICS=1
    Classification: Unclassified
           Product: RTEMS
           Version: HEAD
          Platform: All
        OS/Version: RTEMS
            Status: NEW
          Severity: normal
          Priority: P3
         Component: cpukit
        AssignedTo: joel.sherrill at oarcorp.com
        ReportedBy: pam at oktetlabs.ru


If RTEMS was configured with USE_TICKS_FOR_STATISTICS=1 then clock() function
return value is incorrect (it equals to correct value * 2 in case if single
thread application).
This happens because of incorrect _timeo() function behavior (file
cpukit/libcsupport/src/__times.c):
clock_t _times(
   struct tms  *ptms
)
{
.....
  ticks = rtems_clock_get_ticks_since_boot();
....
  #else
    ptms->tms_utime  = _Thread_Executing->cpu_time_used;
  #endif
  ptms->tms_stime  = ticks;
....
} 

clock() function returns the sum of ptms structure fields, so in case of single
thread application clock() returns (correct value) * 2.

Example code:
rtems_task Init(rtems_task_argument unused)
{
    time_t t, t0;
    clock_t c;
    rtems_time_of_day timeod;

    rtems_clock_set(&timeod);
    t0 = time(NULL);
    while(1)
    {
      t = time(NULL);
      c = clock();
      printf("t: %04i c: %04i [%i]\n", t - t0, c / CLOCKS_PER_SEC, c);
      while(c / CLOCKS_PER_SEC == clock() / CLOCKS_PER_SEC);
    }
    exit(0);
}

Example output:
t: 0000 c: 0000 [0]
t: 0000 c: 0001 [100]
t: 0001 c: 0002 [200]
t: 0001 c: 0003 [300]
t: 0002 c: 0004 [400]
t: 0002 c: 0005 [500]
t: 0003 c: 0006 [600]
.....

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