linux-kernel - Re: S3 resume regression [1cf4f629d9d2 ("cpu/hotplug: Move online calls to hotplugged cpu")]

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Date:   Wed, 9 Nov 2016 11:54:18 +0800
From:   Feng Tang <feng.tang@...el.com>
To:     Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Feng Tang <feng.79.tang@...il.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        Rik van Riel <riel@...hat.com>,
        "Srivatsa S. Bhat" <srivatsa@....edu>,
        Peter Zijlstra <peterz@...radead.org>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Rusty Russell <rusty@...tcorp.com.au>,
        Oleg Nesterov <oleg@...hat.com>, Tejun Heo <tj@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Paul McKenney <paulmck@...ux.vnet.ibm.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Paul Turner <pjt@...gle.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Zhang, Rui" <rui.zhang@...el.com>,
        "Brown, Len" <len.brown@...el.com>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux ACPI <linux-acpi@...r.kernel.org>
Subject: Re: S3 resume regression [1cf4f629d9d2 ("cpu/hotplug: Move online
 calls to hotplugged cpu")]

On Wed, Nov 02, 2016 at 04:47:37AM +0800, Ville Syrjälä wrote:
> On Fri, Oct 28, 2016 at 08:58:41PM +0200, Thomas Gleixner wrote:
> > On Fri, 28 Oct 2016, Ville Syrjälä wrote:
> > > On Thu, Oct 27, 2016 at 10:41:18PM +0200, Thomas Gleixner wrote:
> > > > On Thu, 27 Oct 2016, Ville Syrjälä wrote:
> > > > > On Thu, Oct 27, 2016 at 09:25:05PM +0200, Thomas Gleixner wrote:
> > > > > > So it would be interesting whether that hunk in resume_broadcast() is
> > > > > > sufficient.
> > > > > 
> > > > > So far it looks like the answer is yes.
> > > > > 
> > > > > Looks to be about 5 seconds slower than acpi-idle in resuming, but
> > > > > I suppose that's not all that surprising ;)
> > > > 
> > > > Well, set it to 1msec then. If that works reliably then we really can do
> > > > that unconditionally. There is no harm in firing a useless timer during
> > > > resume once.
> > > 
> > > I narrowed down the required timeout, and looks like 25ms is the
> > > minimum that works. With 24ms I already started to have failures. So
> > > maybe just bump it up by an order of magnitude to 250ms for some
> > > safety margin?
> 
> I left the thing running for the weekend and it failed 26 out of 16057
> times with the 25ms timeout. Looks like it takes ~5 minutes to resume
> when it fails, but eventually it does come back.
> 

Just came back from a travel. Yes, the 5 minutes delay may be due to the
expiration of the HPET timer, counting from 0 to 0xffffffff for a 13M
frequencey HPET takes about 300 seconds. After resume, it seems nobody
arms it so my old patch forces to arm one event. 

Thanks,
Feng