linux-kernel - Re: [PATCH RFC 0/3] sched/fair: cpu time reserves for cgroups

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Message-ID: <20160516111849.GN3193@twins.programming.kicks-ass.net>
Date:	Mon, 16 May 2016 13:18:49 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc:	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
	Tejun Heo <tj@...nel.org>, cgroups@...r.kernel.org,
	containers@...ts.linux-foundation.org
Subject: Re: [PATCH RFC 0/3] sched/fair: cpu time reserves for cgroups

On Mon, May 16, 2016 at 12:36:19PM +0300, Konstantin Khlebnikov wrote:
> This feature allows to change cpu cgroup weight for a limited time.
> 
> Cgroup interface:
> cpu.cfs_reserve_us      - reserved time for each cpu.cfs_period_us
> cpu.cfs_reserve_shares  - group weight during reserved time
> 
> While cfs group consumes reserved cpu time it has different weight,
> thus it gets different vruntime penalty for that execution.
> 
>         ^ weight
>         |
>         |
> reserve |
> shares  -------*
>         |      |
>         |      |
>         |      |
> shares  -      *-----------------*
>         |                        |
>         |                        |
>         0------|-----------------|-----------> time
>                reserve           quota
> 
> Reserve can work as a "low limit": boost weight for "guaranteed" time,
> and as a "high limit": give normal weight for a limited time and allow
> utilize cpu when nobody else needs it.
> 

You forgot to explain why I should care about this.