linux-kernel - Re: Question with maxcpus= parameter.

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Message-ID: <563C46A0.3040608@oracle.com>
Date:	Fri, 6 Nov 2015 14:20:16 +0800
From:	Zhenzhong Duan <zhenzhong.duan@...cle.com>
To:	"Raj, Ashok" <ashok.raj@...el.com>
Cc:	rusty@...tcorp.com.au, LKML <linux-kernel@...r.kernel.org>,
	Feng Jin <joe.jin@...cle.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: Re: Question with maxcpus= parameter.

Thanks for your quick response, Raj.

It's OL6 compatible with rhel6.

zduan
在 2015/11/6 14:57, Raj, Ashok 写道:
> Hi Zduan
>
> do you know which distribution it is? This isn't a kernel bug.
>
> if you look at dmesg you should see how many CPUs were booted. But the sysfs
> files are created and the usermode script is bringing every cpu online.
>
> Tony mentioned this to me couple weeks ago when i was fixing another bug
> in maxcpus. I think you can safely remove the script and it should be fine.
>
> Cheers,
> Ashok
>
>
> On Fri, Nov 06, 2015 at 01:24:16PM +0800, Zhenzhong Duan wrote:
>> Hi Maintainers,
>>
>> Recently we faced an cpu online issue with maxcpus= parameter.
>>
>> We want to have 4 cpus onlined at bootup, test 3.8.13-stable on an 72 cpus
>> env with maxcpus=4, I found more cpus than 4 are onlined.
>> It's the udev scripts make them onlined. But below script exist for a long
>> time.
>> ACTION=="add", KERNEL=="cpu[0-9]*", RUN+="/bin/bash -c 'echo 1 >
>> /sys/devices/system/cpu/%k/online'"
>>
>> maxcpu= parameter didn't take effect, so is this a kernel bug? Or that
>> script should be removed?
>>
>> Btw: 2.6.39 works fine, I checked udev log, seems CPU ADD event is only sent
>> for 4cpus.
>> Why the difference between 2.6.39 and 3.8.13?
>>
>> thanks
>> zduan

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