linux-kernel - Re: [PATCH v10 2/9] cpuset: Add new v2 cpuset.sched.domain

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Date:   Thu, 21 Jun 2018 16:05:10 +0800
From:   Waiman Long <longman@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Tejun Heo <tj@...nel.org>, Li Zefan <lizefan@...wei.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Ingo Molnar <mingo@...hat.com>, cgroups@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        kernel-team@...com, pjt@...gle.com, luto@...capital.net,
        Mike Galbraith <efault@....de>, torvalds@...ux-foundation.org,
        Roman Gushchin <guro@...com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Patrick Bellasi <patrick.bellasi@....com>
Subject: Re: [PATCH v10 2/9] cpuset: Add new v2 cpuset.sched.domain_root flag

On 06/21/2018 03:58 PM, Waiman Long wrote:
> On 06/20/2018 10:27 PM, Peter Zijlstra wrote:
>> On Mon, Jun 18, 2018 at 12:14:01PM +0800, Waiman Long wrote:
>>> +  cpuset.sched.domain_root
>> Why are we calling this a domain_root and not a partition?
> A partition can consist of several cgroups in a tree structure. That
> flag should only be set at the root of a partition. I will change the
> name to partition_root if you think this name is acceptable.
>
>>> +	A read-write single value file which exists on non-root
>>> +	cpuset-enabled cgroups.  It is a binary value flag that accepts
>>> +	either "0" (off) or "1" (on).  This flag is set by the parent
>>> +	and is not delegatable.
>> You still haven't answered:
>> ,  
>>   https://lkml.kernel.org/r/20180531094943.GG12180@hirez.programming.kicks-ass.net
>>
>> the question stands.
> I am sorry to miss your question. Turning on domain_root will affects
> the cpu mapping in the parent. That is why it cannot be set by the child
> as a child is not supposed to be able to affect the parent.

After thinking a bit more about it, you are right that I should not use
the term "not delegatable" here. I will rephrase in the next version.

Cheers,
Longman