linux-kernel - RE: [PATCH 0/5] Enabling the asynchronous threads for other phases

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Message-ID: <27240C0AC20F114CBF8149A2696CBE4A01C2203F@SHSMSX101.ccr.corp.intel.com>
Date:	Mon, 17 Feb 2014 02:10:46 +0000
From:	"Liu, Chuansheng" <chuansheng.liu@...el.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
CC:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"pavel@....cz" <pavel@....cz>, "Brown, Len" <len.brown@...el.com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Li, Zhuangzhi" <zhuangzhi.li@...el.com>
Subject: RE: [PATCH 0/5] Enabling the asynchronous threads for other phases

Hello Rafael,

> -----Original Message-----
> From: Liu, Chuansheng
> Sent: Monday, February 17, 2014 9:44 AM
> To: 'Rafael J. Wysocki'
> Cc: gregkh@...uxfoundation.org; pavel@....cz; Brown, Len;
> linux-pm@...r.kernel.org; linux-kernel@...r.kernel.org; Li, Zhuangzhi
> Subject: RE: [PATCH 0/5] Enabling the asynchronous threads for other phases
> 
> Hello Rafael,
> 
> > -----Original Message-----
> > From: Rafael J. Wysocki [mailto:rjw@...ysocki.net]
> > Sent: Monday, February 17, 2014 7:41 AM
> > To: Liu, Chuansheng
> > Cc: gregkh@...uxfoundation.org; pavel@....cz; Brown, Len;
> > linux-pm@...r.kernel.org; linux-kernel@...r.kernel.org; Li, Zhuangzhi
> > Subject: Re: [PATCH 0/5] Enabling the asynchronous threads for other phases
> >
> > On Monday, February 10, 2014 08:36:57 AM Liu, Chuansheng wrote:
> > > Hello Rafael,
> > >
> > > > -----Original Message-----
> > > > From: Rafael J. Wysocki [mailto:rjw@...ysocki.net]
> > > > Sent: Thursday, February 06, 2014 5:53 AM
> > > > To: Liu, Chuansheng
> > > > Cc: gregkh@...uxfoundation.org; pavel@....cz; Brown, Len;
> > > > linux-pm@...r.kernel.org; linux-kernel@...r.kernel.org; Li, Zhuangzhi
> > > > Subject: Re: [PATCH 0/5] Enabling the asynchronous threads for other
> > phases
> > > >
> > > > On Monday, January 20, 2014 04:44:34 PM Liu, Chuansheng wrote:
> > > > > Hello,
> > > > >
> > > > > This patch series are for enabling the asynchronous threads for the
> > phases
> > > > > resume_noirq, resume_early, suspend_noirq and suspend_late.
> > > > >
> > > > > Just like commit 5af84b82701a and 97df8c12995, with async threads it
> > will
> > > > > reduce the system suspending and resuming time significantly.
> > > > >
> > > > > With these patches, in my test platform, it saved 80% time in
> > resume_noirq
> > > > > phase.
> > > > >
> > > > > Has done the suspend-resume stress test for a long time, please help to
> > > > > review.
> > > > >
> > > > > Best Regards,
> > > > >
> > > > > [PATCH 1/5] PM: Adding two flags for async suspend_noirq and
> > > > > [PATCH 2/5] PM: Enabling the asynchronous threads for resume_noirq
> > > > > [PATCH 3/5] PM: Enabling the asyncronous threads for resume_early
> > > > > [PATCH 4/5] PM: Enabling the asyncronous threads for suspend_noirq
> > > > > [PATCH 5/5] PM: Enabling the asyncronous threads for suspend_late
> > > >
> > > > I've applied this to the bleeding-edge branch of the linux-pm.git tree, with
> > > > minor changes related to coding style, white space etc.
> > > Thanks your help.
> >
> > Unfortunately, I've just realized that your patches don't add any mechanism
> > ensuring that parent devices' .suspend_noirq() will be called *after* the
> > .suspend_noirq() of all their children.  Of course, analogously for
> > .suspend_late() and for the resume part (where children have to wait for
> > their parents).
> >
> > In the original async suspend/resume code that is implemented using
> > power.completion and I suppose you can do the same thing here.
> 
> I think "parent devices suspend after their children" is not related directly
> with using async or not;
> In the original code, even without asyncing, the suspend/resume has the
> waiting
> action, but there no waiting action for suspend_noirq and other phases.
> 
Sorry, re-checked the code, the order in the list has made sure the sequence
of parent-then-children when without asyncing.
Thanks your pointing out, will re-cook this series patch.