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

[Zefan Li <lizefan@huawei.com>]

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@redhat.com wrote:
>>> From: Rik van Riel <riel@redhat.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.