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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 41C71C04AAC for ; Mon, 20 May 2019 15:03:42 +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 C3FD120863 for ; Mon, 20 May 2019 15:03:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C3FD120863 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4572GM4vvvzDqLL for ; Tue, 21 May 2019 01:03:39 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=linux.ibm.com (client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com; envelope-from=nathanl@linux.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.ibm.com Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4572DZ06PVzDqF6 for ; Tue, 21 May 2019 01:02:05 +1000 (AEST) Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x4KF0Y7h008041 for ; Mon, 20 May 2019 11:02:02 -0400 Received: from e16.ny.us.ibm.com (e16.ny.us.ibm.com [129.33.205.206]) by mx0a-001b2d01.pphosted.com with ESMTP id 2skvtp53yt-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 20 May 2019 11:02:02 -0400 Received: from localhost by e16.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 20 May 2019 16:01:59 +0100 Received: from b01ledav006.gho.pok.ibm.com (b01ledav006.gho.pok.ibm.com [9.57.199.111]) by b01cxnp23033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x4KF1wQi39387394 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 20 May 2019 15:01:58 GMT Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E5947AC05F; Mon, 20 May 2019 15:01:57 +0000 (GMT) Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C91D2AC059; Mon, 20 May 2019 15:01:57 +0000 (GMT) Received: from localhost (unknown [9.41.179.184]) by b01ledav006.gho.pok.ibm.com (Postfix) with ESMTP; Mon, 20 May 2019 15:01:57 +0000 (GMT) From: Nathan Lynch To: Tyrel Datwyler Subject: Re: [PATCH 1/3] powerpc/pseries: Simplify cpu readd to use drc_index In-Reply-To: <05a4295b-dea5-bea2-5fd3-c8fbee7bac48@linux.vnet.ibm.com> References: <20190516023706.50118-1-tyreld@linux.ibm.com> <8736leky3x.fsf@linux.ibm.com> <05a4295b-dea5-bea2-5fd3-c8fbee7bac48@linux.vnet.ibm.com> Date: Mon, 20 May 2019 10:01:57 -0500 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 x-cbid: 19052015-0072-0000-0000-000004307096 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00011131; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000286; SDB=6.01206074; UDB=6.00633284; IPR=6.00987033; MB=3.00026971; MTD=3.00000008; XFM=3.00000015; UTC=2019-05-20 15:02:00 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19052015-0073-0000-0000-00004C4B0D6B Message-Id: <87tvdpjhju.fsf@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-05-20_07:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905200098 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: , Cc: mingming.cao@ibm.com, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Tyrel Datwyler writes: > On 05/16/2019 12:17 PM, Nathan Lynch wrote: >> Tyrel Datwyler writes: >>> The current dlpar_cpu_readd() takes in a cpu_id and uses that to look up >>> the cpus device_node so that we can get at the ibm,my-drc-index >>> property. The only user of cpu readd is an OF notifier call back. This >>> call back already has a reference to the device_node and therefore can >>> retrieve the drc_index from the device_node. >> >> dlpar_cpu_readd is a hack to try to change the CPU-node relationship at >> runtime without destabilizing the system. It doesn't accomplish that and >> it should just be removed (and I'm working on that). >> > > I will politely disagree. We've done exactly this from userspace for > years. My experience still suggests that memory affinity is the > problem area, and that the work to push this all into the kernel > originally was poorly tested. Kernel implementation details aside, how do you change the cpu-node relationship at runtime without breaking NUMA-aware applications? Is this not a fundamental issue to address before adding code like this?