hi:

2011/7/11 Mulyadi Santosa [off-list ref]:

Hi...

On Sun, Jul 10, 2011 at ?is 17:27, loody [off-list ref] wrote:

quoted

Dear all:
I have some questions about kthread:
1. can we change kthread priority through user mode program?

Theoritically you can, but only if the priority not fixed and/or you
have required capability to do so

quoted

2. I found some functions that may be helpful.
sched_getscheduler
sched_setscheduler

When I use them in user mode, the return value of sched_setscheduler ?is fail.

did you do that as root? anything blocking you doing that withing
SELinux or AppArmor policy?

I execute it as root.
what is "SELinux or AppArmor policy"?

quoted

there is a thread talking about this,
http://www.spinics.net/lists/linux-rt-users/msg06588.html
What makes me confuse is "these 2 functions is used in user mode or
kernel mode?"

AFAIK they are user mode libc functions...

I found there are the same export_symbols in kernel.
I use them to dynamically change the priority.
It works but I found something interesting:
1. if thread use schedule algorithm of SCHED_NORMAL, it cannot change
the priority.
2. can we set the priority  to any number less than (MAX_USER_RT_PRIO-1)?
( I tried to set the priority as 99, but it fail)
3. can we get the name of thread from task_struct or pid?
(I use "cat /proc/338/status", I can see the name of thread. But I
look around the task_struct, I cannot find any name information in
it.)

Thanks for your kind help,