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

From: Andrew Morton
Date: Sun Jun 18 2006 - 05:49:55 EST


On Sun, 18 Jun 2006 18:26:38 +1000
Peter Williams <pwil3058@xxxxxxxxxxxxxx> 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.
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