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Message-ID: <alpine.DEB.2.20.1610282049500.5053@nanos>
Date: Fri, 28 Oct 2016 20:58:41 +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 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?
Sure, but what puzzles me is that we need a timeout that big. What happens
between broadcast_resume() and broadcast_resume() + 25ms?
IOW, what is the event/resume function which we need to bridge. We should
really try to track than down.
You might try to enable function tracing and do a tracing_off() when that
25ms timeout fires.
Something like
stop_trace = true;
in broadcast_resume() and then in the broadcast timer function:
if (stop_trace) {
stop_trace = false;
tracing_off();
}
Then when the machine is up read the trace, compress and upload it
somewhere or send it in private mail if it's not that big.
Thanks,
tglx
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