Messages in this thread | | | Date | Tue, 7 Jun 2011 10:32:50 +0200 | From | Monica Puig-Pey <> | Subject | Re: Changing Kernel thread priorities |
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El 07/06/11 10:27, Johannes Bauer escribió: > Absolutly correct! > > However, if you are running the system on an embedded platform, where the _WHOLE_ system (including priorities) is preconfigured and never touched, starting a irq thread with the right prio from start is a more straightforward method than having to invoke a script that changes it using userspace chrt tool. > > Regards JB > ----- Ursprüngliche Nachricht ----- > Von: "Peter Zijlstra"<peterz@infradead.org> > Erhalten: 07.06.2011 00:36 > An: hannes_bauer@aon.at > > "Monica Puig-Pey" wrote: >> >> I need to change the priority from inside the driver, when creating the >> kernel thread. > > No you don't. How does you driver know about what priority is correct > wrt all the other running RT tasks on the system? > > Determining the right priority in a fixed priority scheduling system is > a system wide problem, nobody but the administrator can possibly even > begin to solve it. > > There's a reason all RT irq threads are started at 50, its plain > impossible to do better. >
That's it! If I work with embedded system where I know all my tasks running and there is not a user how could I do it?
What I tried is create the kernel thread in my init_module using:
#include <linux/kthread.h>
struct task_struct *kthread_create(int (*threadfn)(void *data), void *data, const char namefmt[], ...) and then running it with:
#include <linux/sched.h>
extern int wake_up_process(struct task_struct *tsk);
These functions stars a Kthread which has a NON RT priority. I can see this using the ps command from user space. Because it's not a real time thread is why I want, better need, to change its priority, to have only real time threads running in my driver. I want to use the Kthread as a bottom half for the interrupts.
How could I create real time kernel threads then? is kthread_create wrong for real time enviroment?
-- __________________________________________________________________________________
Mónica Puig-Pey González E-mail: puigpeym@unican.es
Grupo de Computadores y Tiempo Real, Departamento de Electrónica y Computadores. Facultad de Ciencias - Universidad de Cantabria Av. de los Castros s/n. 39005 - Santander, España __________________________________________________________________________________ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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