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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 56CC0CFD379 for ; Tue, 25 Nov 2025 08:49:29 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4dFxFg46cSz2yvv; Tue, 25 Nov 2025 19:49:27 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=148.163.158.5 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1764060567; cv=none; b=ARVUcxn/HImPz2mM2VsnMP8AHP0v6SxCZfswm0V6I+Oc9pFwnkgVyeYdkeYeOFycxMkVxZmfLEgrywjftxEQIJ0VEwY1a4jkgrTQCpUD1MsOpGNiJxH+qV+Xj3sNTHnohFLGSN1H1iJOnv4T+VZGsoFJnwkHXjB1jxVGWRzV/mV2WumzP9zYObaor32dDWkyyyNsbwEz4ujolqyqYBs7R7s/KV4DA4ikwqI+FRvgUrv5gAgQrspG557IPDo2bo7r8YjvYr6SwWFOjkKRa4H2I/e071w0QSl+tMUrWqrRIAi8YH5aKXsbnRC4UQ3NJm1hezShMZHxH4p4pbnP9vtNeg== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1764060567; c=relaxed/relaxed; bh=xMZW4jYCPZBCYDa9tRwOq2YAcYPcswbaoSrXqxyb2qo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Pa9bKwH061LP/s6NdPqZYfLLNAEuKYjHJuJqOTLrjGqK7VK7YjKl8Un2Mh1lKptrrsnEqU6MjDCSowDEErTQ1z5O9bJo36YkXDeIpW/6zIkTTxop64OjF15GviskuYOfyUvqh5jGwYRsyQLas2/JUBx5VgvEMzVQHDlMc92QxeKML5/gsaXK6L96v7x1Sk0Cgf5Pcndr8eB6qc4hCIF5ql1iBajtfY+SJT7hsn/QJxU88q8vlpyN6HZ73EmwOIcBI+1LZrBQ6Z1PwXumRjTGz8aNfLafWVQGRbS8t+Bs06n5Dm7MdiXqcrCeVghLggr8gM7cKm1AQGAYXDnFfSwTHA== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=bvbtMbjr; dkim-atps=neutral; spf=pass (client-ip=148.163.158.5; helo=mx0b-001b2d01.pphosted.com; envelope-from=sshegde@linux.ibm.com; receiver=lists.ozlabs.org) smtp.mailfrom=linux.ibm.com Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=bvbtMbjr; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.ibm.com (client-ip=148.163.158.5; helo=mx0b-001b2d01.pphosted.com; envelope-from=sshegde@linux.ibm.com; receiver=lists.ozlabs.org) Received: from mx0b-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 4dFxFf2V3Cz2yFJ for ; Tue, 25 Nov 2025 19:49:25 +1100 (AEDT) Received: from pps.filterd (m0353725.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 5AP6s9uO022981; Tue, 25 Nov 2025 08:48:43 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=xMZW4j YCPZBCYDa9tRwOq2YAcYPcswbaoSrXqxyb2qo=; b=bvbtMbjrrgMIFVnYKw9Kra GBaTnCtY2ywhnfy6cQ2hakzGSkfQ9+JMrSIlPlfY2NVkFw3OP08NnaUgANcjhmHu pSqkPYbD7za1BzsvQKYH3PzphCg3JSfmj6Sy2MqEv7M24n7IoLvUI65a7wb5C3b+ ScywLM4TIh/ICQflFUZjq7JOZpwrqvZqi2z/mupbmmfGLqJt19WmKBpna1BKIzwf 977ynKEzYfXTqtVMwJivHcaI9aHLte3iBUZmmcfmtTwopA5xj8R5P/edtlUS/q7A KsWBXN1DeCwlO468xhh/vG+FwK8WTWeJh6q/OF2+cndBUmTz30IUBJA3lt8hujdg == Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4ak3kjuujf-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 25 Nov 2025 08:48:43 +0000 (GMT) Received: from m0353725.ppops.net (m0353725.ppops.net [127.0.0.1]) by pps.reinject (8.18.1.12/8.18.0.8) with ESMTP id 5AP8kK5D032128; Tue, 25 Nov 2025 08:48:42 GMT Received: from ppma23.wdc07v.mail.ibm.com (5d.69.3da9.ip4.static.sl-reverse.com [169.61.105.93]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4ak3kjuujb-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 25 Nov 2025 08:48:42 +0000 (GMT) Received: from pps.filterd (ppma23.wdc07v.mail.ibm.com [127.0.0.1]) by ppma23.wdc07v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id 5AP6W7jd016395; Tue, 25 Nov 2025 08:48:42 GMT Received: from smtprelay03.fra02v.mail.ibm.com ([9.218.2.224]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4aks0k2j88-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 25 Nov 2025 08:48:41 +0000 Received: from smtpav02.fra02v.mail.ibm.com (smtpav02.fra02v.mail.ibm.com [10.20.54.101]) by smtprelay03.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 5AP8mbnP52429202 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 25 Nov 2025 08:48:38 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9A29D20043; Tue, 25 Nov 2025 08:48:37 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 34FF220040; Tue, 25 Nov 2025 08:48:33 +0000 (GMT) Received: from [9.124.217.104] (unknown [9.124.217.104]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 25 Nov 2025 08:48:32 +0000 (GMT) Message-ID: <236f4925-dd3c-41ef-be04-47708c9ce129@linux.ibm.com> Date: Tue, 25 Nov 2025 14:18:32 +0530 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 00/17] Paravirt CPUs and push task for less vCPU preemption To: "Christophe Leroy (CS GROUP)" , Greg KH Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, tglx@linutronix.de, yury.norov@gmail.com, maddy@linux.ibm.com, srikar@linux.ibm.com, pbonzini@redhat.com, seanjc@google.com, kprateek.nayak@amd.com, vschneid@redhat.com, iii@linux.ibm.com, huschle@linux.ibm.com, rostedt@goodmis.org, dietmar.eggemann@arm.com References: <20251119124449.1149616-1-sshegde@linux.ibm.com> <2025112454-phonics-crept-5b98@gregkh> <4b83b443-baa8-4218-8412-ddfb0dda8ac3@linux.ibm.com> <0f53d5b8-dbb7-4265-940a-2f2be3d0154d@kernel.org> Content-Language: en-US From: Shrikanth Hegde In-Reply-To: <0f53d5b8-dbb7-4265-940a-2f2be3d0154d@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: OkAh_KmwgwVl3m2iOFqwMiQG81qqNXFl X-Authority-Analysis: v=2.4 cv=frbRpV4f c=1 sm=1 tr=0 ts=69256d6b cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=6UeiqGixMTsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=l-hnylNqxinosfSD0RAA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: -e_Hl98T10jwpy8ucKF2dydUVGGdS_b9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMTIyMDAwOCBTYWx0ZWRfX+8M1fqDeG9uj x4gjgwWTxv7E2avi0KwfruwAITXrdibcN4M02+Brl3pNdEaHxltEGHcJXhDW+qjovrTU/u3xGTi HRNjDJkq/p945LNP3V5SnWzmip9Rr40CiGG6Nwjxdlek2a+/mskqdYGbyGFuYea+Lz61vO3ZySr aMj8DZgO5lsam42E0Zl853a8X/Xh3H4c1i0x267+JANEffj5w5bp4ylpezEsLV7Micf9yVeCNeh rY6khhotfGIEp/IG0ukGv6Jdgxq9DoEUoYGH2TWt6ScnwtdVizJaASynpRN8XZIcKEJxhHeunxP sJcB1Fdt+p/ZZMeVleF+ikHXH9Ta6IFsp8smnnzKFpb83DLQmr+HZRtsJ5E5WD01TC3otmrjrz9 5gFRt7q7ag5fFZQ4Y4nQghAGVTCqIw== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-11-25_02,2025-11-24_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 suspectscore=0 clxscore=1011 spamscore=0 lowpriorityscore=0 impostorscore=0 bulkscore=0 adultscore=0 priorityscore=1501 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510240000 definitions=main-2511220008 Hi Christophe, Greg >>> >>> There is no "v" for this series :( >>> >> >> I thought about adding v1. >> >> I made it as PATCH from RFC PATCH since functionally it should >> be complete now with arch bits. Since it is v1, I remember usually >> people send out without adding v1. after v1 had tags such as v2. >> >> I will keep v2 for the next series. >> > > But you are listing changes compared to v3, how can it be a v1 ? > Shouldn't it be a v4 ? Or in reality a v5 as you already sent a v4 here > [1]. > > [1] https://lore.kernel.org/all/20251119062100.1112520-1- > sshegde@linux.ibm.com/ > > Christophe Sorry about the confusion in numbers. Hopefully below helps for reviewing. If there are no objections, I will keep next one as v2. Please let me know. Revision logs: ++++++++++++++++++++++++++++++++++++++ RFC PATCH v4 -> PATCH (This series) ++++++++++++++++++++++++++++++++++++++ - Last two patches were sent out separate instead of being with series. Sent it as part of series. - Use DEVICE_ATTR_RW instead (greg) - Made it as PATCH since arch specific handling completes the functionality. +++++++++++++++++++++++++++++++++ RFC PATCH v3 -> RFC PATCH v4 +++++++++++++++++++++++++++++++++ - Introduced computation of steal time in powerpc code. - Derive number of CPUs to use and mark the remaining as paravirt based on steal values. - Provide debugfs knobs to alter how steal time values being used. - Removed static key check for paravirt CPUs (Yury) - Removed preempt_disable/enable while calling stopper (Prateek) - Made select_idle_sibling and friends aware of paravirt CPUs. - Removed 3 unused schedstat fields and introduced 2 related to paravirt handling. - Handled nohz_full case by enabling tick on it when there is CFS/RT on it. - Updated debug patch to override arch behavior for easier debugging during development. - Kept the method to push only current task out instead of moving all task's on rq given the complexity of later. +++++++++++++++++++++++++++++++++ RFC v2 -> RFC PATCH v3 +++++++++++++++++++++++++++++++++ - Renamed to paravirt_cpus_mask - Folded the changes under CONFIG_PARAVIRT. - Fixed the crash due work_buf corruption while using stop_one_cpu_nowait. - Added sysfs documentation. - Copy most of __balance_push_cpu_stop to new one, this helps it move the code out of CONFIG_HOTPLUG_CPU. - Some of the code movement suggested. +++++++++++++++++++++++++++++++++ RFC PATCH -> RFC v2 +++++++++++++++++++++++++++++++++ - Renamed to cpu_avoid_mask in place of cpu_parked_mask. - Used a static key such that no impact to regular case. - add sysfs file to show avoid CPUs. - Make RT understand avoid CPUs. - Add documentation patch - Took care of reported compile error when NR_CPUS=1 PATCH : https://lore.kernel.org/all/20251119124449.1149616-1-sshegde@linux.ibm.com/ RFC PATCH v4 : https://lore.kernel.org/all/20251119062100.1112520-1-sshegde@linux.ibm.com/#r RFC PATCH v3 : https://lore.kernel.org/all/20250910174210.1969750-1-sshegde@linux.ibm.com/#r RFC v2 : https://lore.kernel.org/all/20250625191108.1646208-1-sshegde@linux.ibm.com/#r RFC PATCH : https://lore.kernel.org/all/20250523181448.3777233-1-sshegde@linux.ibm.com/