linux-kernel - RE: [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait or nmi

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Date:	Wed, 06 Jun 2012 10:23:40 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	"Luck, Tony" <tony.luck@...el.com>,
	"Yu, Fenghua" <fenghua.yu@...el.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Ingo Molnar <mingo@...e.hu>, H Peter Anvin <hpa@...or.com>,
	"Siddha, Suresh B" <suresh.b.siddha@...el.com>,
	"Mallick, Asit K" <asit.k.mallick@...el.com>,
	Arjan Dan De Ven <arjan@...ux.intel.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	x86 <x86@...nel.org>, linux-pm <linux-pm@...r.kernel.org>,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Subject: RE: [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait or
 nmi

On Wed, 2012-06-06 at 00:09 +0200, Thomas Gleixner wrote:
> > Well, no not like that, but I think we could do with some coupling
> > there. Like steer active interrupts away when they keep hitting idle
> > state.
> 
> That's possible, but that wants a well coordinated mechanism which
> takes the user space steering into account.

Sure, if the provided interrupt affinity mask doesn't allow this, we
loose. But typically those are all bits set.

> I'm not saying it's impossible, I'm just trying to imagine the extra
> user space interfaces needed for that. 

None, preferably.
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