Re: [RFC PATCH V3 0/3] PM/CPU: Parallel enalbing nonboot cpus with resume devices

[Lan Tianyu <tianyu.lan@intel.com>]

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?
-- 
Best regards
Tianyu Lan