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.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Gautham R Shenoy <ego@in.ibm.com>,
Joel Schopp <jschopp@austin.ibm.com>,
Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
Dipankar Sarma <dipankar@in.ibm.com>,
Balbir Singh <balbir@in.ibm.com>,
Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.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: 26+ 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 ` Gautham R Shenoy
2009-08-28 10:00 ` [PATCH v2 1/2] cpu: Offline state Framework Gautham R Shenoy
2009-08-28 10:00 ` Gautham R Shenoy
2009-09-02 4:49 ` Andrew Morton
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
2009-08-28 10:00 ` Gautham R Shenoy
2009-09-02 5:33 ` [PATCH v2 0/2] cpu: pseries: Offline state framework Peter Zijlstra
2009-09-02 5:33 ` Peter Zijlstra
2009-09-02 20:02 ` Pavel Machek
2009-09-02 20:02 ` Pavel Machek
2009-09-24 0:48 ` Benjamin Herrenschmidt
2009-09-24 0:48 ` Benjamin Herrenschmidt
2009-09-24 7:51 ` Peter Zijlstra [this message]
2009-09-24 7:51 ` Peter Zijlstra
2009-09-24 8:38 ` Benjamin Herrenschmidt
2009-09-24 8:38 ` Benjamin Herrenschmidt
2009-09-24 11:33 ` Peter Zijlstra
2009-09-24 11:33 ` Peter Zijlstra
2009-09-24 11:41 ` Arjan van de Ven
2009-09-24 11:41 ` Arjan van de Ven
2009-09-25 7:25 ` Vaidyanathan Srinivasan
2009-09-25 7:25 ` Vaidyanathan Srinivasan
2009-09-25 7:42 ` Arjan van de Ven
2009-09-25 7:42 ` Arjan van de Ven
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1253778667.7695.130.camel@twins \
--to=a.p.zijlstra@chello.nl \
--cc=benh@kernel.crashing.org \
--cc=djwong@us.ibm.com \
--cc=ego@in.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=venkatesh.pallipadi@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.