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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 19DB2C3279B for ; Wed, 4 Jul 2018 08:31:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D02F02086A for ; Wed, 4 Jul 2018 08:31:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D02F02086A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.vnet.ibm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933936AbeGDIbf (ORCPT ); Wed, 4 Jul 2018 04:31:35 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:56612 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932363AbeGDIbd (ORCPT ); Wed, 4 Jul 2018 04:31:33 -0400 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w648UAbj115062 for ; Wed, 4 Jul 2018 04:31:32 -0400 Received: from e35.co.us.ibm.com (e35.co.us.ibm.com [32.97.110.153]) by mx0a-001b2d01.pphosted.com with ESMTP id 2k0spjtt40-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 04 Jul 2018 04:31:32 -0400 Received: from localhost by e35.co.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) Wed, 4 Jul 2018 02:31:29 -0600 Received: from b03ledav006.gho.boulder.ibm.com (b03ledav006.gho.boulder.ibm.com [9.17.130.237]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w648VSUk11141546 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 4 Jul 2018 01:31:28 -0700 Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 36B96C605B; Wed, 4 Jul 2018 02:31:28 -0600 (MDT) Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E2AAEC6057; Wed, 4 Jul 2018 02:31:27 -0600 (MDT) Received: from sofia.ibm.com (unknown [9.124.35.39]) by b03ledav006.gho.boulder.ibm.com (Postfix) with ESMTP; Wed, 4 Jul 2018 02:31:27 -0600 (MDT) Received: by sofia.ibm.com (Postfix, from userid 1000) id 9DD9B2E2F43; Wed, 4 Jul 2018 13:45:05 +0530 (IST) Date: Wed, 4 Jul 2018 13:45:05 +0530 From: Gautham R Shenoy To: Murilo Opsfelder Araujo Cc: "Gautham R. Shenoy" , Michael Ellerman , Benjamin Herrenschmidt , Michael Neuling , Vaidyanathan Srinivasan , Akshay Adiga , Shilpasri G Bhat , "Oliver O'Halloran" , Nicholas Piggin , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [v2 PATCH 2/2] powerpc: Enable CPU_FTR_ASYM_SMT for interleaved big-cores Reply-To: ego@linux.vnet.ibm.com References: <573a559dff87da1d68a55bf6ada97b7697102909.1530609795.git.ego@linux.vnet.ibm.com> <20180703175346.GB6474@kermit-br-ibm-com.br.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180703175346.GB6474@kermit-br-ibm-com.br.ibm.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-TM-AS-GCONF: 00 x-cbid: 18070408-0012-0000-0000-00001686CD89 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009306; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000266; SDB=6.01056336; UDB=6.00541869; IPR=6.00834258; MB=3.00021987; MTD=3.00000008; XFM=3.00000015; UTC=2018-07-04 08:31:31 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18070408-0013-0000-0000-0000538CF115 Message-Id: <20180704081505.GB1007@in.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-07-04_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=940 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1806210000 definitions=main-1807040101 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Murilo, Thanks for the review. On Tue, Jul 03, 2018 at 02:53:46PM -0300, Murilo Opsfelder Araujo wrote: [..snip..] > > - /* Initialize CPU <=> thread mapping/ > > + if (has_interleaved_big_core) { > > + int key = __builtin_ctzl(CPU_FTR_ASYM_SMT); > > + > > + cur_cpu_spec->cpu_features |= CPU_FTR_ASYM_SMT; > > + static_branch_enable(&cpu_feature_keys[key]); > > + pr_info("Detected interleaved big-cores\n"); > > + } > > Shouldn't we use cpu_has_feature(CPU_FTR_ASYM_SMT) before setting > > it? Are you suggesting that we do the following? if (has_interleaved_big_core && !cpu_has_feature(CPU_FTR_ASYM_SMT)) { ... } Currently CPU_FTR_ASYM_SMT is set at compile time for only POWER7 where running the tasks on lower numbered threads give us the benefit of SMT thread folding. Interleaved big core is a feature introduced only on POWER9. Thus, we know that CPU_FTR_ASYM_SMT is not set in cpu_features at this point. > > > + > > + /* Initialize CPU <=> thread mapping/ > > * > > * WARNING: We assume that the number of threads is the same for > > * every CPU in the system. If that is not the case, then some code > > -- > > 1.9.4 > > > > -- > Murilo -- Thanks and Regards gautham.