From: Heiko Carstens <heiko.carstens@de.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] s390/topology: add drawer scheduling domain level
Date: Mon, 13 Jun 2016 13:22:30 +0200 [thread overview]
Message-ID: <20160613112230.GA3808@osiris> (raw)
In-Reply-To: <20160613110621.GV30909@twins.programming.kicks-ass.net>
On Mon, Jun 13, 2016 at 01:06:21PM +0200, Peter Zijlstra wrote:
> On Wed, Jun 08, 2016 at 11:09:16AM +0200, Heiko Carstens wrote:
> > The z13 machine added a fourth level to the cpu topology
> > information. The new top level is called drawer.
> >
> > A drawer contains two books, which used to be the top level.
> >
> > Adding this additional scheduling domain did show performance
> > improvements for some workloads of up to 8%, while there don't
> > seem to be any workloads impacted in a negative way.
>
> Right; so no objection.
>
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Thanks!
> You still don't want to make NUMA explicit on this thing? So while I
> suppose the SC 480M L4 cache does hide some of it, there can be up to 8
> nodes on this thing. Which seems to me there's win to be had by exposing
> it.
>
> Of course, the moment you go all virt/LPAR on it, that all gets really
> interesting, but for those cases where you run 1:1 it might make sense.
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.
> Also, are you sure you don't want some of the behaviour changed for the
> drawer domains? I could for example imagine you wouldn't want
> SD_WAKE_AFFINE set (we disable that for NUMA domains as well).
That's something we need to look into further as well. Thanks for pointing
this out!
next prev parent reply other threads:[~2016-06-13 12:23 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 [this message]
2016-06-13 13:06 ` Peter Zijlstra
2016-06-13 13:19 ` Martin Schwidefsky
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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