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From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] s390/topology: add drawer scheduling domain level
Date: Mon, 13 Jun 2016 15:19:42 +0200	[thread overview]
Message-ID: <20160613151942.02028e15@mschwide> (raw)
In-Reply-To: <20160613130647.GZ30909@twins.programming.kicks-ass.net>

On Mon, 13 Jun 2016 15:06:47 +0200
Peter Zijlstra <peterz@infradead.org> wrote:

> On Mon, Jun 13, 2016 at 01:22:30PM +0200, Heiko Carstens wrote:
> > Yes, and actually we are all virt/LPAR always, so this is unfortunately not
> > very easy to do. And yes, I do agree that for the 1:1 case it most likely
> > would make sense, however we don't have any run-time guarantee to stay 1:1.
> 
> One option would be to make it a boot option; such that the
> administrator has to set it. At that point, if the admin creates
> multiple LPARs its on him.

Unfortunately not good enough. The LPAR code tries to optimize the layout
at the time a partition is activated. The landscape of already running
partitions can change at this point.

To get around this you would have to activate *all* partitions first and
then start the operating systems in a second step.

And then there is concurrent repair which will move things around if a
piece of memory goes bad. This happens rarely though.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.

  reply	other threads:[~2016-06-13 13:20 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-08  9:09 [PATCH 0/2] s390: introduce drawer scheduling domain Heiko Carstens
2016-06-08  9:09 ` [PATCH 1/2] topology/sysfs: provide drawer id and siblings attributes Heiko Carstens
2016-06-08  9:09 ` [PATCH 2/2] s390/topology: add drawer scheduling domain level Heiko Carstens
2016-06-13 11:06   ` Peter Zijlstra
2016-06-13 11:22     ` Heiko Carstens
2016-06-13 13:06       ` Peter Zijlstra
2016-06-13 13:19         ` Martin Schwidefsky [this message]
2016-06-13 13:53           ` Peter Zijlstra
2016-06-13 14:37             ` Martin Schwidefsky
2016-06-13 11:25     ` Heiko Carstens
2016-06-13 11:33       ` Peter Zijlstra

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