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_PASS,URIBL_BLOCKED,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 6563AC67863 for ; Wed, 24 Oct 2018 10:41:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3245620832 for ; Wed, 24 Oct 2018 10:41:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3245620832 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 S1727361AbeJXTJI (ORCPT ); Wed, 24 Oct 2018 15:09:08 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:42584 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726913AbeJXTJI (ORCPT ); Wed, 24 Oct 2018 15:09:08 -0400 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w9OAZwuH068795 for ; Wed, 24 Oct 2018 06:41:32 -0400 Received: from e06smtp07.uk.ibm.com (e06smtp07.uk.ibm.com [195.75.94.103]) by mx0b-001b2d01.pphosted.com with ESMTP id 2naq4b88vb-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 24 Oct 2018 06:41:32 -0400 Received: from localhost by e06smtp07.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) Wed, 24 Oct 2018 11:41:27 +0100 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w9OAfQis7471604 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 24 Oct 2018 10:41:26 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B9B674C04E; Wed, 24 Oct 2018 10:41:26 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C99ED4C040; Wed, 24 Oct 2018 10:41:24 +0000 (GMT) Received: from linux.vnet.ibm.com (unknown [9.126.150.29]) by d06av22.portsmouth.uk.ibm.com (Postfix) with SMTP; Wed, 24 Oct 2018 10:41:24 +0000 (GMT) Date: Wed, 24 Oct 2018 16:11:24 +0530 From: Srikar Dronamraju To: Peter Zijlstra Cc: Mel Gorman , Ingo Molnar , LKML , Rik van Riel , Yi Wang , zhong.weidong@zte.com.cn, Yi Liu , Frederic Weisbecker , Thomas Gleixner Subject: Re: [PATCH v2] sched/core: Don't mix isolcpus and housekeeping CPUs Reply-To: Srikar Dronamraju References: <1540350169-18581-1-git-send-email-srikar@linux.vnet.ibm.com> <20181024085636.GB23537@techsingularity.net> <20181024094646.GA18466@linux.vnet.ibm.com> <20181024101508.GP3109@worktop.c.hoisthospitality.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20181024101508.GP3109@worktop.c.hoisthospitality.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-TM-AS-GCONF: 00 x-cbid: 18102410-0028-0000-0000-0000030C683A X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18102410-0029-0000-0000-000023C87557 Message-Id: <20181024104124.GC18466@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-10-24_04:,, 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=8.0.1-1807170000 definitions=main-1810240095 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Peter Zijlstra [2018-10-24 12:15:08]: > On Wed, Oct 24, 2018 at 03:16:46PM +0530, Srikar Dronamraju wrote: > > * Mel Gorman [2018-10-24 09:56:36]: > > > > > On Wed, Oct 24, 2018 at 08:32:49AM +0530, Srikar Dronamraju wrote: > > > It would certainly be a bit odd because the > > > application is asking for some protection but no guarantees are given > > > and the application is not made aware via an error code that there is a > > > problem. Asking the application to parse dmesg hoping to find the right > > > error message is going to be fragile. > > > > Its a actually a good question. > > What should we be doing if a mix of isolcpus and housekeeping (aka > > non-isolcpus) is given in the mask. > > > > Right now as you pointed, there is no easy way for the application to know > > which are the non-isolcpus to set its affinity. cpusets effective_cpus and > > cpus_allowed both will contain isolcpus too. > > The easy option is to not use isolcpus :-) It is a horrifically bad > interface. Agree, but thats something thats been exposed long time back. Do we have an option to remove that? Hopefully nobody is using it. -- Thanks and Regards Srikar Dronamraju