From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Gautham R Shenoy <ego@in.ibm.com>,
linux-kernel@vger.kernel.org,
Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>,
Arun R Bharadwaj <arun@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org,
"Darrick J. Wong" <djwong@us.ibm.com>
Subject: Re: [PATCH v3 0/3] cpu: pseries: Cpu offline states framework
Date: Sat, 26 Sep 2009 07:12:48 +1000 [thread overview]
Message-ID: <1253913169.7103.529.camel@pasglop> (raw)
In-Reply-To: <1253890120.18939.189.camel@laptop>
On Fri, 2009-09-25 at 16:48 +0200, Peter Zijlstra wrote:
> On Thu, 2009-09-24 at 10:51 +1000, Benjamin Herrenschmidt wrote:
> > On Tue, 2009-09-15 at 14:11 +0200, Peter Zijlstra wrote:
> > > I still think its a layering violation... its the hypervisor manager
> > > that should be bothered in what state an off-lined cpu is in.
> > >
> > That's not how our hypervisor works.
>
> Then fix it?
Are you serious ? :-)
> CPU hotplug is terribly invasive and expensive to the kernel, doing
> hotplug on a minute basis is just plain crazy.
>
> If you want a CPU in a keep it near and don't hand it back to the HV
> state, why not use cpusets to isolate it and simply not run tasks on it?
>
> cpusets don't use stopmachine and are much nicer to the rest of the
> kernel over-all.
Gautham, what is the different in term of power saving between having
it idle for long periods of time (which could do H_CEDE and with NO_HZ,
probably wouln't need to wake up that often) and having it unplugged in
a H_CEDE loop ?
Ben.
next prev parent reply other threads:[~2009-09-25 21:15 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-15 12:06 [PATCH v3 0/3] cpu: pseries: Cpu offline states framework Gautham R Shenoy
2009-09-15 12:07 ` [PATCH v3 1/3] pSeries: cede latency specifier helper function Gautham R Shenoy
2009-09-15 14:45 ` Daniel Walker
2009-09-15 12:07 ` [PATCH v3 2/3] cpu: Offline state Framework Gautham R Shenoy
2009-09-30 17:31 ` Randy Dunlap
2009-09-15 12:07 ` [PATCH v3 3/3] cpu: Implement cpu-offline-state callbacks for pSeries Gautham R Shenoy
2009-09-15 12:11 ` [PATCH v3 0/3] cpu: pseries: Cpu offline states framework Peter Zijlstra
2009-09-15 13:21 ` Michael Ellerman
2009-09-15 14:58 ` Balbir Singh
2009-09-16 7:48 ` Heiko Carstens
2009-09-24 0:52 ` Benjamin Herrenschmidt
2009-09-16 15:28 ` Dipankar Sarma
2009-09-16 15:32 ` Peter Zijlstra
2009-09-16 16:24 ` Dipankar Sarma
2009-09-16 16:35 ` Peter Zijlstra
2009-09-16 17:03 ` Vaidyanathan Srinivasan
2009-09-16 17:22 ` Peter Zijlstra
2009-09-16 20:17 ` Dipankar Sarma
2009-09-24 0:55 ` Benjamin Herrenschmidt
2009-09-24 0:51 ` Benjamin Herrenschmidt
2009-09-25 14:48 ` Peter Zijlstra
2009-09-25 21:12 ` Benjamin Herrenschmidt [this message]
2009-09-28 13:53 ` Vaidyanathan Srinivasan
2009-09-28 13:51 ` Vaidyanathan Srinivasan
2009-09-26 9:55 ` Pavel Machek
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=1253913169.7103.529.camel@pasglop \
--to=benh@kernel.crashing.org \
--cc=a.p.zijlstra@chello.nl \
--cc=arun@linux.vnet.ibm.com \
--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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).