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

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Message-ID: <alpine.DEB.2.20.1610272238390.4913@nanos>
Date:   Thu, 27 Oct 2016 22:41:18 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Ville Syrjälä <ville.syrjala@...ux.intel.com>
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, 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.

> > Does the machine work, when you limit intel idle to C3, which would then
> > match acpi idle ?
> 
> I'm pretty sure I had tested all of these, but I just double checked
> to make sure. There's no C3 with intel_idle so I limited to C2, but
> that did not help.
> 
> Isn't it possible that ACPI C3 is in fact C4? I thought ACPI C-states
> are always numbered non-sparsely, and in this case ACPI C3 could be
> anything from C3 to C11 (if the processor actually supported such
> states obviously). Actually now that I look at the descriptions for
> the states in sysfs, it says "MWAIT 0x30" for state3 on both drivers,
> which I presume means it's in fact C4 for both.

Indeed.

Thanks,

	tglx