linux-kernel - Re: [PATCH V4 7/9] cpuidle/powernv: Add "Fast-Sleep" CPU idle state

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Date:	Mon, 2 Dec 2013 19:00:20 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
cc:	fweisbec@...il.com, paul.gortmaker@...driver.com, paulus@...ba.org,
	shangw@...ux.vnet.ibm.com, rjw@...k.pl, paulmck@...ux.vnet.ibm.com,
	arnd@...db.de, linux-pm@...r.kernel.org, rostedt@...dmis.org,
	michael@...erman.id.au, john.stultz@...aro.org,
	chenhui.zhao@...escale.com, deepthi@...ux.vnet.ibm.com,
	r58472@...escale.com, geoff@...radead.org,
	linux-kernel@...r.kernel.org, srivatsa.bhat@...ux.vnet.ibm.com,
	schwidefsky@...ibm.com, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH V4 7/9] cpuidle/powernv: Add "Fast-Sleep" CPU idle
 state

On Mon, 2 Dec 2013, Preeti U Murthy wrote:
> On 11/29/2013 08:09 PM, Thomas Gleixner wrote:
> > This supports HIGHRES and NO_HZ if done right, without polling at
> > all. So you can even let the last CPU which handles the broadcast
> > hrtimer go for a long sleep, just not in the deepest idle state.
> 
> Thank you for the review. The above points are all valid. I will rework
> the design to:
> 
> 1. Eliminate the concept of a broadcast CPU and integrate its
> functionality in the timekeeping CPU.
> 
> 2. Avoid polling by using IPIs to communicate the next wakeup of the
> CPUs in deep idle state so as to reprogram the broadcast hrtimer.
> 
> 3. Make this feature generic and not arch-specific.

Great. If you need help with the generic bits, please let me know.

Thanks,

	tglx
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