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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 0E11AC43331 for ; Fri, 6 Sep 2019 03:43:23 +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 40172206BB for ; Fri, 6 Sep 2019 03:43:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 40172206BB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.vnet.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 46Pk133C2BzDr7m for ; Fri, 6 Sep 2019 13:43:19 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=linux.vnet.ibm.com (client-ip=148.163.158.5; helo=mx0a-001b2d01.pphosted.com; envelope-from=srikar@linux.vnet.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.vnet.ibm.com Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (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 46Pjyn4zzlzDr6q for ; Fri, 6 Sep 2019 13:41:20 +1000 (AEST) Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x863ajMV141132 for ; Thu, 5 Sep 2019 23:41:15 -0400 Received: from e06smtp03.uk.ibm.com (e06smtp03.uk.ibm.com [195.75.94.99]) by mx0b-001b2d01.pphosted.com with ESMTP id 2uuddkbt7b-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 05 Sep 2019 23:41:15 -0400 Received: from localhost by e06smtp03.uk.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) Fri, 6 Sep 2019 04:41:13 +0100 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x863fCse39125184 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 6 Sep 2019 03:41:12 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 067F34C052; Fri, 6 Sep 2019 03:41:12 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DBDEB4C058; Fri, 6 Sep 2019 03:41:10 +0000 (GMT) Received: from linux.vnet.ibm.com (unknown [9.126.150.29]) by d06av22.portsmouth.uk.ibm.com (Postfix) with SMTP; Fri, 6 Sep 2019 03:41:10 +0000 (GMT) Date: Fri, 6 Sep 2019 09:11:10 +0530 From: Srikar Dronamraju To: Nathan Lynch Subject: Re: [PATCH v2 3/4] powerpc/numa: Early request for home node associativity References: <20190829055023.6171-1-srikar@linux.vnet.ibm.com> <20190829055023.6171-4-srikar@linux.vnet.ibm.com> <87tv9qqzm7.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <87tv9qqzm7.fsf@linux.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-TM-AS-GCONF: 00 x-cbid: 19090603-0012-0000-0000-0000034750C1 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19090603-0013-0000-0000-00002181A92A Message-Id: <20190906034110.GA12412@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-09-06_02:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 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=8.0.1-1906280000 definitions=main-1909060039 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: Satheesh Rajendran , linuxppc-dev , Nicholas Piggin Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" > > > > While here, fix a problem where of_node_put could be called even when > > of_get_cpu_node was not successful. > > of_node_put() handles NULL arguments, so this should not be necessary. > Ok > > @@ -875,7 +908,7 @@ void __init mem_topology_setup(void) > > reset_numa_cpu_lookup_table(); > > > > for_each_present_cpu(cpu) > > - numa_setup_cpu(cpu); > > + numa_setup_cpu(cpu, false); > > } > > I'm open to other points of view here, but I would prefer two separate > functions, something like vphn_get_nid() for runtime and > vphn_get_nid_early() (which could be __init) for boot-time > initialization. Propagating a somewhat unexpressive boolean flag through > two levels of function calls in this code is unappealing... > Somehow not convinced that we need to duplicate function just to avoid passing a bool. If propagating a boolean flag in two levels of function calls is an issue, we could decipher the logic in numa_setup_cpu itself Something like this static int numa_setup_cpu(unsigned long lcpu, bool get_hwid) { .... if (firmware_has_feature(FW_FEATURE_VPHN)) { long hwid; if (get_hwid) hwid = get_hard_smp_processor_id(cpu); else hwid = cpu_to_phys_id[cpu]; nid = vphn_get_nid(lcpu, hwid); } .... Would this help? > Regardless, I have an annoying question :-) Isn't it possible that, > while Linux is calling vphn_get_nid() for each logical cpu in sequence, > the platform could change a virtual processor's node assignment, > potentially causing sibling threads to get different node assignments > and producing an incoherent topology (which then leads to sched domain > assertions etc)? > Right, its certainly possible for node assignment to change while we iterate through the siblings. Do you have an recommendations? > If so, I think more care is needed. The algorithm should make the vphn > call only once per cpu node, I think? I didn't get "once per cpu node", How do we know which all cpus are part of that cpu node? Or did you mean once per cpu core? -- Thanks and Regards Srikar Dronamraju