From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>,
cgroups@vger.kernel.org, containers@lists.linux-foundation.org
Subject: Re: [PATCH RFC 0/3] sched/fair: cpu time reserves for cgroups
Date: Mon, 16 May 2016 15:22:22 +0300 [thread overview]
Message-ID: <5739BB7E.8010902@yandex-team.ru> (raw)
In-Reply-To: <20160516111849.GN3193@twins.programming.kicks-ass.net>
On 16.05.2016 14:18, Peter Zijlstra wrote:
> 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.
As I told this works as low-limit or high-limit which allow to
control cpu time distribution without hard limits and throttling.
Present quota/hard limit has well known problems when it throttle task
inside kernel where it holds mutexes. Also it's too strict and doesn't
allow utilization of unused cpu time.
--
Konstantin
next prev parent reply other threads:[~2016-05-16 12:23 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-16 9:36 [PATCH RFC 0/3] sched/fair: cpu time reserves for cgroups Konstantin Khlebnikov
2016-05-16 9:36 ` [PATCH RFC 1/3] sched/fair: call __refill_cfs_bandwidth_runtime only for finite quota Konstantin Khlebnikov
2016-05-16 9:36 ` [PATCH RFC 2/3] sched/fair: copy taskgroup shares to each cfs_rq Konstantin Khlebnikov
2016-05-16 9:36 ` [PATCH RFC 3/3] sched/fair: pulse-weight modulation controller for cpu cgroup Konstantin Khlebnikov
2016-05-16 11:18 ` [PATCH RFC 0/3] sched/fair: cpu time reserves for cgroups Peter Zijlstra
2016-05-16 12:22 ` Konstantin Khlebnikov [this message]
2016-05-16 12:26 ` Peter Zijlstra
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