Re: [rt sched] SCHED_FIFO task of lower rt_priority blocks higher one

[Xianwei Zeng <linux.xianwei.zeng@gmail.com>]

Hi,

Thanks for your replies.

I made a mistake about the priority inside the kernel and
sched_setscheduler system call.
I thought both of them are the same: numerically lower priority value
is higher schedule priority.
But in fact, they are opposite:

  * Kernel: numerically lower value is high priority
  * sched_setscheduler() and related system calls:  numerically lower
value is lower priority

It is said in  "man sched_get_priority_max" output:

       Processes with numerically higher priority values  are
scheduled  before  processes
       with numerically lower priority values. Thus, the value
returned by sched_get_prior-
       ity_max() will be greater than the value returned by
sched_get_priority_min().

Thanks.

On Thu, Mar 4, 2010 at 12:52 PM, Karthik Singaram Lakshmanan
<karthiksingaram@gmail.com> wrote:
> Hi,
>     If I am not mistaken, higher value of sched_priority denotes higher
> priority.
>     Therefore, looking at
>         normal_prio = MAX_RT_PRIO - 1 - task->rt_priority;
>         you can see that a higher task->rt_priority will translate to a
> lower value of normal_prio, thereby occupying an earlier bit.


-- 
Best Regards,
Zeng Xianwei
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