Re: [PATCH v4 2/2] cpusets,isolcpus: add file to show isolated cpus in cpuset

[Zefan Li]

On 2015/3/2 17:12, Peter Zijlstra wrote:
> On Mon, Mar 02, 2015 at 02:15:39PM +0800, Zefan Li wrote:
>> Hi Rik,
>>
>>> Subject: cpusets,isolcpus: add file to show isolated cpus in cpuset
>>>
>>> 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.
>>>
>>
>> One Question, why not add a /sys/devices/system/cpu/isolated instead?
> 
> It would leave userspace to calculate the result for any one cpuset
> itself.

It's trivial. Instead of reading cpuset.isolcpus, now we read cpuset.cpus
and /sys/.../isolated.

> Furthermore, is that /sys thing visible for all nested
> containers?
> .
> 

Never tried nested containers, but I think so.

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