linux-kernel - Re: [PATCH 3/4] cpusets,isolcpus: add file to show isolated cpus in cpuset

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Message-ID: <550A6C7C.1030204@huawei.com>
Date:	Thu, 19 Mar 2015 14:28:12 +0800
From:	Zefan Li <lizefan@...wei.com>
To:	Rik van Riel <riel@...hat.com>
CC:	Tejun Heo <tj@...nel.org>, <linux-kernel@...r.kernel.org>,
	<cgroups@...r.kernel.org>, Peter Zijlstra <peterz@...radead.org>,
	"Clark Williams" <williams@...hat.com>,
	Ingo Molnar <mingo@...hat.com>,
	"Luiz Capitulino" <lcapitulino@...hat.com>,
	David Rientjes <rientjes@...gle.com>,
	Mike Galbraith <umgwanakikbuti@...il.com>
Subject: Re: [PATCH 3/4] cpusets,isolcpus: add file to show isolated cpus
 in cpuset

On 2015/3/19 9:54, Rik van Riel wrote:
> On 03/18/2015 09:50 PM, Zefan Li wrote:
>> On 2015/3/19 7:40, Rik van Riel wrote:
>>> On 03/18/2015 12:47 PM, Tejun Heo wrote:
>>>> On Mon, Mar 09, 2015 at 12:12:09PM -0400, riel@...hat.com wrote:
>>>>> From: Rik van Riel <riel@...hat.com>
>>>>>
>>>>> The previous patch makes it so the code skips over isolcpus when
>>>>> building scheduler load balancing domains. This makes it hard to
>>>>> see for a user which of the CPUs in a cpuset are participating in
>>>>> load balancing, and which ones are isolated cpus.
>>>>>
>>>>> Add a cpuset.isolcpus file with info on which cpus in a cpuset are
>>>>> isolated CPUs.
>>>>>
>>>>> This file is read-only for now. In the future we could extend things
>>>>> so isolcpus can be changed at run time, for the root (system wide)
>>>>> cpuset only.
>>>>
>>>> Didn't Li say that this is trivially computable from userland?  I'm
>>>> not sure this knob actually belongs to cpuset.
>>>
>>> I don't know whether the information to compute this is
>>> always visible from userland.  I am happy to drop this
>>> patch if Li prefers things that way, though.
>>>
>>
>> What I proposed is adding /sys/devices/system/cpu/isolated. Sysfs is
>> visible in containers, unless specially configured not so.
> 
> OK, are you willing to take patches 1, 2, and the first hunk of patch
> 4 now? I can submit a patch to add /sys/devices/system/cpu/isolated
> on Friday, to the appropriate maintainer.
> 

Other patches look good to me.

> (taking tomorrow off to go hiking on the last full day of winter)
> 

Have a good day!

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