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

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Message-ID: <20161028155603.GI4617@intel.com>
Date:   Fri, 28 Oct 2016 18:56:03 +0300
From:   Ville Syrjälä <ville.syrjala@...ux.intel.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Feng Tang <feng.79.tang@...il.com>, feng.tang@...el.com,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        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>,
        Len Brown <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 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?

In any case I think I'll leave the machine running S3 cycles over the
weekend with the 25ms timeout just to see if it will eventually fail.

-- 
Ville Syrjälä
Intel OTC