Message-ID: <5447495A.1060102@intel.com>
Date: Wed, 22 Oct 2014 14:06:18 +0800
From: Lan Tianyu <tianyu.lan@intel.com>
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To: Peter Zijlstra <peterz@infradead.org>
CC: mingo@kernel.org, rafael.j.wysocki@intel.com, toshi.kani@hp.com,
        akpm@linux-foundation.org, ktkhai@parallels.com, fabf@skynet.be,
        laijs@cn.fujitsu.com, srivatsa.bhat@linux.vnet.ibm.com,
        ego@linux.vnet.ibm.com, srivatsa@mit.edu, viresh.kumar@linaro.org,
        todd.e.brandt@linux.intel.com, tipbot@zytor.com,
        wangyun@linux.vnet.ibm.com, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [RFC PATCH V3 0/3] PM/CPU: Parallel enalbing nonboot cpus with
 resume devices
References: <1411633925-9018-1-git-send-email-tianyu.lan@intel.com> <20141008205441.GJ4750@worktop.programming.kicks-ass.net> <5435E275.3030307@intel.com>
In-Reply-To: <5435E275.3030307@intel.com>
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Sender: linux-kernel-owner@vger.kernel.org

On 2014年10月09日 09:18, Lan Tianyu wrote:
> On 2014年10月09日 04:54, Peter Zijlstra wrote:
>> On Thu, Sep 25, 2014 at 04:32:02PM +0800, Lan Tianyu wrote:
>>> This patchset is to parallel enabling nonboot cpus with resuming devices
>>> during system resume in order to accelerate S2RAM. From test result on
>>> a 8 logical core Haswell machine, system resume time reduces from 347ms
>>> to 217ms with this patchset.
>>>
>>> In the current world, all nonboot cpus are enabled serially during system
>>> resume. System resume sequence is that boot cpu enables nonboot cpu one by
>>> one and then resume devices. Before resuming devices, there are few tasks
>>> assigned to nonboot cpus after they are brought up. This wastes cpu usage.
>>>
>>> This patchset is to allow boot cpu to go forward to resume devices after
>>> bringing up one nonboot cpu and starting a thread. The thread will be in
>>> charge of bringing up other frozen cpus. The thread will be scheduled to
>>> the first online cpu to run . This makes enabling cpu2~x parallel with
>>> resuming devices.
>>
>> So I feel we should really clean up hotplug before doing anything like
>> this. Its a trainwreck and just piling more and more hacks ontop isn't
>> going to help any.
>>
> 
> Hi Peter:
> 	Sorry, I don't know the gap of hotplug clearly. Could you elaborate it?
> 

Hi Peter:
	Could you elaborate the gap of hotplug? Thanks.

-- 
Best regards
Tianyu Lan
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