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=-3.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 46FF2C433DB for ; Tue, 2 Mar 2021 10:29:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EEC956146D for ; Tue, 2 Mar 2021 10:29:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1380076AbhCBK0u (ORCPT ); Tue, 2 Mar 2021 05:26:50 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:34648 "EHLO mx0b-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1382726AbhCBKGe (ORCPT ); Tue, 2 Mar 2021 05:06:34 -0500 Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 122A4xke114843; Tue, 2 Mar 2021 05:05:35 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=date : from : to : cc : subject : message-id : reply-to : references : mime-version : content-type : in-reply-to; s=pp1; bh=HqLHTHXwW8rBcNfn1K9a51+eOv+SrdOqAPiRIkPTBQY=; b=j8JUTUVK4LdRyQfGsY9FJkXZvZAG+eKDxN66ANGCdZbJxVlCaSdf5yUWwmM0FjhpHl9l +vk7uzYzq/X10rRCZ+mgyusjgpDUXU/QqNmimxx+iEpNC6NEPvbcME6S+3AaAgvMDfXR SIiEWyrLcN07H01asZMitAWad/rafqZusF95WZolCTqP6vyPNpGZNJafI6TuZHc2nAoY Dx8eWB66mOYSPQHlOqX4Q2sB/iLGRAjCfwW8BHgiAdQCXrvND0XGBPCAMq1XlofvXyAI 4E4hJpfKE/psjoXD7OM5SXr7VFWL6EjjxGxHmlPQW89exFtD4z+/8x+Gnsiu5xlW34gr kg== Received: from ppma06ams.nl.ibm.com (66.31.33a9.ip4.static.sl-reverse.com [169.51.49.102]) by mx0a-001b2d01.pphosted.com with ESMTP id 371gvtnb68-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 02 Mar 2021 05:05:34 -0500 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 122A3I6E025678; Tue, 2 Mar 2021 10:05:32 GMT Received: from b06cxnps4075.portsmouth.uk.ibm.com (d06relay12.portsmouth.uk.ibm.com [9.149.109.197]) by ppma06ams.nl.ibm.com with ESMTP id 370c59srpe-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 02 Mar 2021 10:05:32 +0000 Received: from d06av24.portsmouth.uk.ibm.com (mk.ibm.com [9.149.105.60]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 122A5UWH3015320 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 2 Mar 2021 10:05:30 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8239642047; Tue, 2 Mar 2021 10:05:30 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 14BBA42049; Tue, 2 Mar 2021 10:05:28 +0000 (GMT) Received: from linux.vnet.ibm.com (unknown [9.126.150.29]) by d06av24.portsmouth.uk.ibm.com (Postfix) with SMTP; Tue, 2 Mar 2021 10:05:27 +0000 (GMT) Date: Tue, 2 Mar 2021 15:35:27 +0530 From: Srikar Dronamraju To: Peter Zijlstra Cc: Rik van Riel , Ingo Molnar , LKML , Mel Gorman , Thomas Gleixner , Valentin Schneider , Vincent Guittot , Dietmar Eggemann , Michael Ellerman , Michael Neuling , Gautham R Shenoy , Parth Shah Subject: Re: [PATCH] sched/fair: Prefer idle CPU to cache affinity Message-ID: <20210302100527.GN2028034@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <20210226164029.122432-1-srikar@linux.vnet.ibm.com> <20210301170601.GJ2028034@linux.vnet.ibm.com> <20210302073946.GL2028034@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-03-02_03:2021-03-01,2021-03-02 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 priorityscore=1501 clxscore=1015 lowpriorityscore=0 impostorscore=0 bulkscore=0 mlxscore=0 suspectscore=0 mlxlogscore=894 spamscore=0 phishscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2103020082 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Peter Zijlstra [2021-03-02 10:10:32]: > On Tue, Mar 02, 2021 at 01:09:46PM +0530, Srikar Dronamraju wrote: > > > Oh, could be, I didn't grep :/ We could have core code keep track of the > > > smt count I suppose. > > > > Could we use cpumask_weight(cpu_smt_mask(this_cpu)) instead? > > cpumask_weight() is potentially super expensive. With CPUMASK_OFFSTACK > you get at least one more cache miss and then the bitmap might be really > long. > > Best to compute the results once and use it later. Oh okay .. Noted. -- Thanks and Regards Srikar Dronamraju