linux-kernel - Re: [PATCH] Extend mwait idle to optimize away CAL and RES interrupts to an idle CPU -v1

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Date:	Fri, 24 Feb 2012 13:41:50 +0800
From:	Yong Zhang <yong.zhang0@...il.com>
To:	Venki Pallipadi <venki@...gle.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Aaron Durbin <adurbin@...gle.com>,
	Paul Turner <pjt@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Extend mwait idle to optimize away CAL and RES
 interrupts to an idle CPU -v1

On Thu, Feb 23, 2012 at 11:34:11AM -0800, Venki Pallipadi wrote:
> On Thu, Feb 23, 2012 at 1:30 AM, Peter Zijlstra <peterz@...radead.org> wrote:
> > Why not scheduler_ipi()?
> 
> Was trying to avoid irq_enter/exit. As the work here is done in idle
> thread context, I though we could avoid enter/exit. 

It seems we could not.
At least RCU need it, see commit c5d753a55, otherwise we will get
warning like 'RCU used illegally from extended quiescent state!'

Thanks,
Yong
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