From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Gautham R Shenoy <ego@in.ibm.com>,
Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
"Darrick J. Wong" <djwong@us.ibm.com>
Subject: Re: [PATCH v2 0/2] cpu: pseries: Offline state framework.
Date: Thu, 24 Sep 2009 09:51:07 +0200 [thread overview]
Message-ID: <1253778667.7695.130.camel@twins> (raw)
In-Reply-To: <1253753307.7103.356.camel@pasglop>
On Thu, 2009-09-24 at 10:48 +1000, Benjamin Herrenschmidt wrote:
> On Wed, 2009-09-02 at 07:33 +0200, Peter Zijlstra wrote:
> >
> > I'm still thinking this is a bad idea.
> >
> > The OS should only know about online/offline.
> >
> > Use the hypervisor interface to deal with the cpu once its offline.
> >
> > That is, I think this interface you propose is a layering violation.
> >
> I don't quite follow your logic here. This is useful for more than just
> hypervisors. For example, take the HV out of the picture for a moment
> and imagine that the HW has the ability to offline CPU in various power
> levels, with varying latencies to bring them back.
cpu-hotplug is an utter slow path, anybody saying latency and hotplug in
the same sentence doesn't seem to grasp either or both concepts.
next prev parent reply other threads:[~2009-09-24 7:55 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-28 10:00 [PATCH v2 0/2] cpu: pseries: Offline state framework Gautham R Shenoy
2009-08-28 10:00 ` [PATCH v2 1/2] cpu: Offline state Framework Gautham R Shenoy
2009-09-02 4:49 ` Andrew Morton
2009-08-28 10:00 ` [PATCH v2 2/2] cpu: Implement cpu-offline-state driver for pSeries Gautham R Shenoy
2009-09-02 5:33 ` [PATCH v2 0/2] cpu: pseries: Offline state framework Peter Zijlstra
2009-09-02 20:02 ` Pavel Machek
2009-09-24 0:48 ` Benjamin Herrenschmidt
2009-09-24 7:51 ` Peter Zijlstra [this message]
2009-09-24 8:38 ` Benjamin Herrenschmidt
2009-09-24 11:33 ` Peter Zijlstra
2009-09-24 11:41 ` Arjan van de Ven
2009-09-25 7:25 ` Vaidyanathan Srinivasan
2009-09-25 7:42 ` Arjan van de Ven
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