From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965188AbcFMLGZ (ORCPT ); Mon, 13 Jun 2016 07:06:25 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:56276 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964790AbcFMLGY (ORCPT ); Mon, 13 Jun 2016 07:06:24 -0400 Date: Mon, 13 Jun 2016 13:06:21 +0200 From: Peter Zijlstra To: Heiko Carstens Cc: Greg Kroah-Hartman , Martin Schwidefsky , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] s390/topology: add drawer scheduling domain level Message-ID: <20160613110621.GV30909@twins.programming.kicks-ass.net> References: <1465376956-100711-1-git-send-email-heiko.carstens@de.ibm.com> <1465376956-100711-3-git-send-email-heiko.carstens@de.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1465376956-100711-3-git-send-email-heiko.carstens@de.ibm.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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) 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. 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).