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Thu, 6 Aug 2020 14:09:56 +0000 (GMT) Received: from linux.vnet.ibm.com (unknown [9.126.150.29]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with SMTP; Thu, 6 Aug 2020 14:09:56 +0000 (GMT) Date: Thu, 6 Aug 2020 19:39:55 +0530 From: Srikar Dronamraju To: peterz@infradead.org Cc: Michael Ellerman , Ingo Molnar , LKML , Mel Gorman , Rik van Riel , Thomas Gleixner , Valentin Schneider , Vincent Guittot , Dietmar Eggemann , linuxppc-dev , Michael Neuling , Gautham R Shenoy , Vaidyanathan Srinivasan Subject: Re: [PATCH 1/2] sched/topology: Allow archs to override cpu_smt_mask Message-ID: <20200806140955.GC31068@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <20200804033307.76111-1-srikar@linux.vnet.ibm.com> <20200804104520.GB2657@hirez.programming.kicks-ass.net> <20200804121007.GJ24375@linux.vnet.ibm.com> <20200804124755.GJ2674@hirez.programming.kicks-ass.net> <87ft90z6dy.fsf@mpe.ellerman.id.au> <20200806085429.GX2674@hirez.programming.kicks-ass.net> <87d044yn9z.fsf@mpe.ellerman.id.au> <20200806131547.GC2674@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20200806131547.GC2674@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-08-06_09:2020-08-06,2020-08-06 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 mlxlogscore=999 lowpriorityscore=0 spamscore=0 impostorscore=0 mlxscore=0 phishscore=0 clxscore=1015 malwarescore=0 suspectscore=1 bulkscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008060096 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * peterz@infradead.org [2020-08-06 15:15:47]: > > But my understanding is most LPARs don't get migrated back and forth, > > they'll start life on a P8 and only get migrated to a P9 once when the > > customer gets a P9. They might then run for a long time (months to > > years) on the P9 in P8 compat mode, not because they ever want to > > migrate back to a real P8, but because the software in the LPAR is still > > expecting to be on a P8. > > > > I'm not a real expert on all the Enterprisey stuff though, so someone > > else might be able to give us a better picture. > > > > But the point of mentioning the migration stuff was mainly just to > > explain why we feel we need to present SMT8 to userspace even on P9. > > OK, fair enough. The patch wasn't particularly onerous, I was just > wondering why etc.. > > The case of starting on a P8 and being migrated to a P9 makes sense to > me; in that case you'd like to rebuild your sched domains, but can't go > about changing user visible topolofy information. > > I suppose: > > Acked-by; Peter Zijlstra (Intel) > > An updated Changelog that recaps some of this discussion might also be > nice. Okay, will surely do the needful. -- Thanks and Regards Srikar Dronamraju From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DC660C433DF for ; Thu, 6 Aug 2020 14:13:01 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 38C70204FD for ; Thu, 6 Aug 2020 14:13:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="biM7AnJd" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 38C70204FD Authentication-Results: mail.kernel.org; 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Thu, 06 Aug 2020 10:10:03 -0400 Received: from pps.filterd (ppma06ams.nl.ibm.com [127.0.0.1]) by ppma06ams.nl.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 076E772b025010; Thu, 6 Aug 2020 14:10:01 GMT Received: from b06avi18878370.portsmouth.uk.ibm.com (b06avi18878370.portsmouth.uk.ibm.com [9.149.26.194]) by ppma06ams.nl.ibm.com with ESMTP id 32mynh5hw5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 06 Aug 2020 14:10:01 +0000 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 076E9xKF65012028 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 6 Aug 2020 14:09:59 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 19B2AA405F; Thu, 6 Aug 2020 14:09:59 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8ED15A4060; Thu, 6 Aug 2020 14:09:56 +0000 (GMT) Received: from linux.vnet.ibm.com (unknown [9.126.150.29]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with SMTP; Thu, 6 Aug 2020 14:09:56 +0000 (GMT) Date: Thu, 6 Aug 2020 19:39:55 +0530 From: Srikar Dronamraju To: peterz@infradead.org Subject: Re: [PATCH 1/2] sched/topology: Allow archs to override cpu_smt_mask Message-ID: <20200806140955.GC31068@linux.vnet.ibm.com> References: <20200804033307.76111-1-srikar@linux.vnet.ibm.com> <20200804104520.GB2657@hirez.programming.kicks-ass.net> <20200804121007.GJ24375@linux.vnet.ibm.com> <20200804124755.GJ2674@hirez.programming.kicks-ass.net> <87ft90z6dy.fsf@mpe.ellerman.id.au> <20200806085429.GX2674@hirez.programming.kicks-ass.net> <87d044yn9z.fsf@mpe.ellerman.id.au> <20200806131547.GC2674@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20200806131547.GC2674@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-08-06_09:2020-08-06, 2020-08-06 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 mlxlogscore=999 lowpriorityscore=0 spamscore=0 impostorscore=0 mlxscore=0 phishscore=0 clxscore=1015 malwarescore=0 suspectscore=1 bulkscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008060096 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Srikar Dronamraju Cc: Gautham R Shenoy , Michael Neuling , Vincent Guittot , Rik van Riel , linuxppc-dev , LKML , Valentin Schneider , Thomas Gleixner , Mel Gorman , Ingo Molnar , Dietmar Eggemann Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" * peterz@infradead.org [2020-08-06 15:15:47]: > > But my understanding is most LPARs don't get migrated back and forth, > > they'll start life on a P8 and only get migrated to a P9 once when the > > customer gets a P9. They might then run for a long time (months to > > years) on the P9 in P8 compat mode, not because they ever want to > > migrate back to a real P8, but because the software in the LPAR is still > > expecting to be on a P8. > > > > I'm not a real expert on all the Enterprisey stuff though, so someone > > else might be able to give us a better picture. > > > > But the point of mentioning the migration stuff was mainly just to > > explain why we feel we need to present SMT8 to userspace even on P9. > > OK, fair enough. The patch wasn't particularly onerous, I was just > wondering why etc.. > > The case of starting on a P8 and being migrated to a P9 makes sense to > me; in that case you'd like to rebuild your sched domains, but can't go > about changing user visible topolofy information. > > I suppose: > > Acked-by; Peter Zijlstra (Intel) > > An updated Changelog that recaps some of this discussion might also be > nice. Okay, will surely do the needful. -- Thanks and Regards Srikar Dronamraju