linux-kernel - Re: Is there a way to offload everything from cpu0 to other cpus?

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Message-ID: <CAOtvUMdok1Hc63FbiPu-rm2EJxpDtLOf2ZWPhsqa=m0tr8TyVw@mail.gmail.com>
Date:	Mon, 15 Aug 2011 09:25:03 +0300
From:	Gilad Ben-Yossef <gilad@...yossef.com>
To:	Américo Wang <xiyou.wangcong@...il.com>
Cc:	Andy Lutomirski <luto@....edu>,
	"Yung, Winson W" <winson.w.yung@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Is there a way to offload everything from cpu0 to other cpus?

On Mon, Aug 8, 2011 at 12:41 PM, Américo Wang <xiyou.wangcong@...il.com> wrote:
> On Fri, Aug 5, 2011 at 8:48 PM, Andy Lutomirski <luto@....edu> wrote:
>> On 08/04/2011 10:53 PM, Yung, Winson W wrote:
>>>
>>> Hi, I would like to know whether it is possible to offload everything
>>> (kernel threads/user apps) to cpu1...x so that I can force cpu0 go into
>>> idle?

...
>>
>> You probably want the isolcpus boot option.
>
> I think Yung was looking for an interface to move tasks dynamically
> after the system is boot.
>
> Yung, why /sys/devices/system/cpu/cpuX/online doesn't work for you?

I believe setting up a cpuset for cpus 1 to x (call it the system set)
and a seperate cpuset for cpu 0 (call it the shielded set) and
re-assigning all non CPU bound kernel tasks from the root cpuset to
the system cpu set is a better option.

There's a guide on how to do that on the RT wiki:
https://rt.wiki.kernel.org/index.php/CPU_shielding_using_/proc_and_/dev/cpuset

Gilad


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