[Xenomai] rt_task_sleep_until() miss release point?

[ZIV-Alberto Ozalla Cantabrana <alberto.ozalla@cgglobal.com>]

Hi all,

enclosed you will find two examples:

  *   rt_task_sleep_until() missing release point, and
  *   rt_task_sleep_until() working fine.

In the first example:

Current time: t1=4205571 ms - Calculated next release point: t2= 4205572 ms
Real release: t3=4205574 ms

Many Thanks
Alberto Ozalla

Simplest example that shows the issue:
________________________________
static RT_TASK Test_Task_descriptor;

static void Test_Task(void *arg)
{
    RTIME t1, t2;
    rt_task_set_mode(0, 0, NULL);

    while(1) {

        t1 = rt_timer_tsc();
        t2 = t1 + 24000;        // 24000 tsc = 1 ms

        cu_log(CU_LOG_ERR, "t1(%lld)-t2(%lld)", rt_timer_tsc2ns(t1), rt_timer_tsc2ns(t2));
        rt_task_sleep_until(rt_timer_tsc2ns(t2));
        cu_log(CU_LOG_ERR, "t3(%lld)", rt_timer_tsc2ns(rt_timer_tsc()));
    }
}

void main(void)
{
    ...
    // Real-time function creation.
       if (int err = rt_task_create(&Test_Task_descriptor, "Test_Task", 0, 79, 0)) {
             cu_log(CU_LOG_ERR, "Error creating Test_Task (%d)", err);
         }

     // Real-time function started.
       if(rt_task_start(&Test_Task_descriptor, &Test_Task, NULL)) {
             cu_log(CU_LOG_ERR, "Error starting Test_Task");
       }
     ...
}

Log traces:

t1(4205571256580)-t2(4205572256580) ns
t3(4205574861288)
t1(4205575085163)-t2(4205576 085163)
t3(4205578686872)
t1(4205578899038)-t2(4205579 899038)
t3(4205582499538)
t1(4205582839455)-t2(4205583 839455)
t3(4205586444497)
t1(4205586669455)-t2(4205587 669455)
t3(4205590273872)
________________________________
Additional data:

Xenomai 2.6.4
Linux version 3.14.17 (gcc version 4.7.3 (GCC) )
#1 SMP 20<6>kernel: [    0.000000] CPU: ARMv7 Processor [413fc082] revision 2 (ARMv7), cr=10c5387d
2000/01/03,02:42:00  kern.info kernel: [    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
2000/01/03,02:42:00  kern.info kernel: [    0.000000] Machine model: TI AM335x BeagleBone
2000/01/03,02:42:00  kern.info kernel: [    0.000000] CPU: All CPU(s) started in SVC mode.
2000/01/03,02:42:00  kern.info kernel: [    0.000000] AM335X ES2.1 (sgx neon )
________________________________
In the other hand, this example works fine:

static void Test_Task(void *arg)
{
    rt_task_set_mode(0, 0, NULL);

    RTIME t1, t2;

    while(1) {
        t1 = rt_timer_read();
        t2 = t1 + 1000000;        //  1 ms

        cu_log(CU_LOG_ERR, "t1(%lld)-t2(%lld)", t1, t2);
        rt_task_sleep_until(t2);
        cu_log(CU_LOG_ERR, "t3(%lld)", rt_timer_read());
    }
}

t1(564272 373824)-t2(564273 373824)
t3(564273 387783)
________________________________
Many Thanks
Alberto Ozalla

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