From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <559E65FB.8080904@sigmatek.at>
Date: Thu, 09 Jul 2015 14:15:55 +0200
From: Johann Obermayr <johann.obermayr@sigmatek.at>
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Subject: [Xenomai] usage of rtdm_task_sleep_abs
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To: Xenomai@xenomai.org

Hello,

we have follow situation

u64 lrtdrv_time_of_irq_ns ;
void worker_task()
{
while(1)
     {
     rtdm_task_sleep_abs(lrtdrv_time_of_irq_ns + 950000ull, 
RTDM_TIMERMODE_ABSOLUTE);
     do_something();
     }
}

_kernel_rtdm_irq_handler()
{
     lrtdrv_time_of_irq_ns = rtdm_clock_read_monotonic();
}

the  _kernel_irq_callback() is called every 1ms.
we will , that the worker_task begin 50us before next irq

But sometime, the worker task start ~50us after irq. Why ?

Sometime we call xntbase_adjust_time to sync external RTC with internal 
clocks.
can this be a problem ?

Hardware & Software
X86 SMP Dual celeron
Linux Kernel 3.10.0
Xenomai 2.6.3

Regards
   Johann