[LITMUS^RT] System calls definition and task creation

[Björn Brandenburg]

On 05 Jun 2014, at 11:06, Chandrasekaran Sivakumar <chandru.a6 at gmail.com> wrote:

> Hi all, 
> In order to modify the task model in litmus-rt, I need to know where and how the tasks are being created. When I tried to back trace from rtspin.c, everything leads to syscall function called from liblitmus/src/syscalls.c Could anyone please tell me where is task creation done ? 
> 
> Thanks & Regards,
> chandru


Hi Chandru,

your tracing pointed out the right spot. Task "creation" is a kernel service, so it is invoked via system calls.

In LITMUS^RT, a task first sets its parameters with set_rt_task_param()

	userspace: https://github.com/LITMUS-RT/liblitmus/blob/master/src/syscalls.c#L20
	kernel: https://github.com/LITMUS-RT/litmus-rt/blob/master/litmus/litmus.c#L96

 and then transitions to real-time mode with task_mode(), which is a wrapper around sched_setscheduler():

	userspace: https://github.com/LITMUS-RT/liblitmus/blob/master/src/task.c#L71
	kernel: https://github.com/LITMUS-RT/litmus-rt/blob/master/kernel/sched/core.c#L3942

Regards,
Björn