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From: Peter Zijlstra <peterz@infradead.org>
To: Martin Schwidefsky <schwidefsky@de.ibm.com>
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 15:53:02 +0200	[thread overview]
Message-ID: <20160613135302.GA30909@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160613151942.02028e15@mschwide>

On Mon, Jun 13, 2016 at 03:19:42PM +0200, Martin Schwidefsky wrote:
> 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.

Would not the admin _know_ this? It would be him activating partitions
after all, no?

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

Arguably, you only care about the single partition covering the entire
machine case, so I don't see that being a problem.

Again, admin _knows_ this.

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

That would be magic disturbance indeed, nothing much to do about that.

  reply	other threads:[~2016-06-13 13:53 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
2016-06-13 13:53           ` Peter Zijlstra [this message]
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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