Re: [REPORT] cfs-v4 vs sd-0.44

[Jan Engelhardt <jengelh@linux01.gwdg.de>]

On Apr 21 2007 18:00, Ingo Molnar wrote:
>* Con Kolivas <kernel@kolivas.org> wrote:
>
>> >   Feels even better, mouse movements are very smooth even under high 
>> >   load. I noticed that X gets reniced to -19 with this scheduler. 
>> >   I've not looked at the code yet but this looked suspicious to me. 
>> >   I've reniced it to 0 and it did not change any behaviour. Still 
>> >   very good.
>> 
>> Looks like this code does it:
>> 
>> +int sysctl_sched_privileged_nice_level __read_mostly = -19;
>
>correct. Note that Willy reniced X back to 0 so it had no relevance on 
>his test. Also note that i pointed this change out in the -v4 CFS 
>announcement:
>
>|| Changes since -v3:
>||
>||  - usability fix: automatic renicing of kernel threads such as 
>||    keventd, OOM tasks and tasks doing privileged hardware access
>||    (such as Xorg).
>
>i've attached it below in a standalone form, feel free to put it into 
>SD! :)

Assume X went crazy (lacking any statistics, I make the unproven
statement that this happens more often than kthreads going berserk),
then having it niced with minus something is not too nice.



Jan
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