Re: changing timeslice in linux

From: Xin Tong
Date: Mon Aug 20 2012 - 10:51:48 EST


On Sun, Aug 19, 2012 at 10:54 PM, Mike Galbraith <efault@xxxxxx> wrote:
> On Sun, 2012-08-19 at 11:58 -0700, Xin Tong wrote:
>> I have 2 questions about linux 2.6 x86_64 scheduler.
>>
>> 1. is the default scheduling algorithm SCHED_NORMAL in linux ?
>
> Yes.
Is there any document describing what the sched_normal is ? it is more
difficult than SCHED_RR to infer its meaning just based on its name ?
>
>> 2. how do i change the time slice in linux source code ?
>
> You shouldn't need to. You can tune "slice" by adjusting
> sched_latency_ns and sched_min_granularity_ns, but note that "slice" is
> not a fixed quantum. Also note that CFS preemption decisions are based
> upon instantaneous state. A task may have received a full (variable)
> "slice" of CPU time, but preemption will be triggered only if a more
> deserving task is available, so a "slice" is not the "max uninterrupted
> CPU time" that you may expect it to be.. but it is somewhat similar.
>
> -Mike
>
This can be done without recompiling and reinstalling the kernel ?
maybe one simply needs to write to a device file under /dev ?

Xin
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