linux-kernel - [PATCH 0/3] cpuidle: updates related to tick_broadcast

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Message-ID: <8965830.CMQzZzsqm0@vostro.rjw.lan>
Date:	Sun, 10 May 2015 01:15:50 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>, peterz@...radead.org
Cc:	tglx@...utronix.de, rafael.j.wysocki@...el.com,
	daniel.lezcano@...aro.org, rlippert@...gle.com,
	linux-pm@...r.kernel.org, linus.walleij@...aro.org,
	linux-kernel@...r.kernel.org, mingo@...hat.com,
	sudeep.holla@....com, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH 0/3] cpuidle: updates related to tick_broadcast_enter() failures

On Saturday, May 09, 2015 10:33:05 PM Rafael J. Wysocki wrote:
> On Saturday, May 09, 2015 10:11:41 PM Rafael J. Wysocki wrote:
> > On Saturday, May 09, 2015 11:19:16 AM Preeti U Murthy wrote:
> > > Hi Rafael,
> > > 
> > > On 05/08/2015 07:48 PM, Rafael J. Wysocki wrote:
> > 
> > [cut]
> > 
> > > >>  
> > > >> +	/* Take note of the planned idle state. */
> > > >> +	idle_set_state(smp_processor_id(), target_state);
> > > > 
> > > > And I wouldn't do this either.
> > > > 
> > > > The behavior here is pretty much as though the driver demoted the state chosen
> > > > by the governor and we don't call idle_set_state() again in those cases.
> > > 
> > > Why is this wrong?
> > 
> > It is not "wrong", but incomplete, because demotions done by the cpuidle driver
> > should also be taken into account in the same way.
> > 
> > But I'm seeing that the recent patch of mine that made cpuidle_enter_state()
> > call default_idle_call() was a mistake, because it might confuse find_idlest_cpu()
> > significantly as to what state the CPU is in.  I'll drop that one for now.
> 
> OK, done.
> 
> So after I've dropped it I think we need to do three things:
> (1) Move the idle_set_state() calls to cpuidle_enter_state().
> (2) Make cpuidle_enter_state() call default_idle_call() again, but this time
>     do that *before* it has called idle_set_state() for target_state.
> (3) Introduce demotion as per my last patch.
> 
> Let me cut patches for that.

Done as per the above and the patches follow in replies to this messge.

All on top of the current linux-next branch of the linux-pm.git tree.


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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