Re: Changing Kernel thread priorities

From: Mark Hounschell
Date: Mon Jun 06 2011 - 13:03:57 EST


On 06/06/2011 07:58 AM, Monica Puig-Pey wrote:
El 06/06/11 13:54, Rolando Martins escribió:
Hi,
I use the following:

PIDs=$(ps -eLo pid,cls,rtprio,pri,nice,cmd | grep -i "irq" | awk '{
print $1; }' | xargs echo)
for i in $PIDs
do
ret=$(chrt -f -p 99 $i)
done

This will change the kernel thread associated with an irq handler to
RT FIFO prio 99.
Just change the script to your specific interrupt.

Hope it helps,
Rolando

On Mon, Jun 6, 2011 at 12:47 PM, Monica Puig-Pey<puigpeym@xxxxxxxxx>
wrote:
I am writing a driver which has one kernel thread associated with it.
I want to change the priority of this thread, so that I can specify the
order in which it is scheduled following an interrupt.
I'm using:

sched_setscheduler(struct task_struct *, int, struct sched_param *);

but it doesn't work. I tried to change the priority from the
init_module,
and also from the Kernel Thread, but there is no way.

Kernel version is 2.6.31-11-rt

What do I call to change a kernel thread priority?

Thanks you very much

Mónica

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I need to change the priority from inside the driver, when creating the
kernel thread.
Your script is useful but it is done in user context,
Any other help please?

What I do is record the PID of the thread in the driver, then create an IOCTL for your driver that user land can call that either returns the PID so you can do it in user land, or cause the IOCTL code to do it in the driver.

The same can be done with the affinity of the IRQ if you record the IRQ number.

Mark
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