Re: [PATCH 0/4] sched: Add CPU rate caps

[Andrew Morton <akpm@osdl.org>]

On Sun, 18 Jun 2006 18:26:38 +1000
Peter Williams <pwil3058@bigpond.net.au> wrote:

> These patches implement CPU usage rate limits for tasks.

Via /proc/pid/cpu_rate_cap.  Important detail, that.

People are going to want to extend this to capping a *group* of tasks, with
some yet-to-be-determined means of tying those tasks together.  How well
suited is this code to that extension?

If the task can exceed its cap without impacting any other tasks (ie: there
is spare idle capacity), what happens?  I trust that spare capacity gets
used?  (Is this termed "work conserving"?)

> 5. Code size measurements:
> 
> Vanilla kernel:
> 
>    text    data     bss     dec     hex filename
>   33800    4689     296   38785    9781 sched.o
>    2554      79       0    2633     a49 mutex.o
>   12076    2632       0   14708    3974 base.o
> 
> Patches applied:
> 
>    text    data     bss     dec     hex filename
>   36870    4721     296   41887    a39f sched.o
>    2630      79       0    2709     a95 mutex.o
>   13011    2920       0   15931    3e3b base.o
> 
> Indicating that the size cost of the patch proper is about
> 3 kilobytes and the procfs costs about another 1.2 kilobytes.
> 

hm.  That seems rather a lot.  I guess it's not a simple thing to do.