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=-5.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 9ACD6C433DF for ; Mon, 17 Aug 2020 12:03:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 73E8C2067C for ; Mon, 17 Aug 2020 12:03:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726971AbgHQMD3 (ORCPT ); Mon, 17 Aug 2020 08:03:29 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:3064 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726135AbgHQMDZ (ORCPT ); Mon, 17 Aug 2020 08:03:25 -0400 Received: from dggeme755-chm.china.huawei.com (unknown [172.30.72.55]) by Forcepoint Email with ESMTP id ADE95C4E4428103920DA; Mon, 17 Aug 2020 20:03:21 +0800 (CST) Received: from [10.174.186.8] (10.174.186.8) by dggeme755-chm.china.huawei.com (10.3.19.101) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1913.5; Mon, 17 Aug 2020 20:03:21 +0800 Subject: Re: [RFC][PATCH 0/4] arm64:kvm: teach guest sched that VCPUs can be preempted To: Sergey Senozhatsky , "will@kernel.org" , "maz@kernel.org" References: <20200721041742.197354-1-sergey.senozhatsky@gmail.com> <20200817020310.GA1210848@jagdpanzerIV.localdomain> CC: , "linux-kernel@vger.kernel.org" , , "kvmarm@lists.cs.columbia.edu" , "linux-arm-kernel@lists.infradead.org" , "Wanghaibin (D)" , From: yezengruan Message-ID: Date: Mon, 17 Aug 2020 20:03:09 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <20200817020310.GA1210848@jagdpanzerIV.localdomain> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.174.186.8] X-ClientProxiedBy: dggeme707-chm.china.huawei.com (10.1.199.103) To dggeme755-chm.china.huawei.com (10.3.19.101) X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/8/17 10:03, Sergey Senozhatsky wrote: > On (20/07/21 13:17), Sergey Senozhatsky wrote: >> Hello, >> >> RFC >> >> We noticed that in a number of cases when we wake_up_process() >> on arm64 guest we end up enqueuing that task on a preempted VCPU. The culprit >> appears to be the fact that arm64 guests are not aware of VCPU preemption >> as such, so when sched picks up an idle VCPU it always assumes that VCPU >> is available: >> >> wake_up_process() >> try_to_wake_up() >> select_task_rq_fair() >> available_idle_cpu() >> vcpu_is_preempted() // return false; >> >> Which is, obviously, not the case. >> >> This RFC patch set adds a simple vcpu_is_preempted() implementation so >> that scheduler can make better decisions when it search for the idle >> (v)CPU. > Hi, > > A gentle ping. > > -ss > _______________________________________________ > kvmarm mailing list > kvmarm@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/kvmarm > . Hi Sergey, I have a set of patches similar to yours. https://lore.kernel.org/lkml/20191226135833.1052-1-yezengruan@huawei.com/