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Date: Tue, 25 Aug 2015 17:13:42 -0400
From: Tejun Heo <tj@kernel.org>
To: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Turner <pjt@google.com>, Austin S Hemmelgarn <ahferroin7@gmail.com>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
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        kernel-team <kernel-team@fb.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 3/3] sched: Implement interface for cgroup unified
 hierarchy
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Hello, Kame.

On Tue, Aug 25, 2015 at 11:36:25AM +0900, Kamezawa Hiroyuki wrote:
> I think I should explain my customer's use case of qemu + cpuset/cpu (via libvirt)
> 
> (1) Isolating hypervisor thread.
>    As already discussed, hypervisor threads are isolated by cpuset. But their purpose
>    is to avoid _latency_ spike caused by hypervisor behavior. So, "nice" cannot be solution
>    as already discussed.
> 
> (2) Fixed rate vcpu service.
>    With using cpu controller's quota/period feature, my customer creates  vcpu models like
>    Low(1GHz), Mid(2GHz), High(3GHz) for IaaS system.
> 
>    To do this, each vcpus should be quota-limited independently, with per-thread cpu control.
> 
> Especially, the method (1) is used in several enterprise customers for stabilizing their system.
> 
> Sub-process control should be provided by some way.

Can you please take a look at the proposal on my reply to Paul's
email?  AFAICS, both of above cases should be fine with that.

Thanks.

-- 
tejun