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=-12.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 0594AC433DB for ; Tue, 2 Feb 2021 07:59:43 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 878E864EE9 for ; Tue, 2 Feb 2021 07:59:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 878E864EE9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.80388.147056 (Exim 4.92) (envelope-from ) id 1l6qat-000556-6W; Tue, 02 Feb 2021 07:59:27 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 80388.147056; Tue, 02 Feb 2021 07:59:27 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l6qat-00054z-38; Tue, 02 Feb 2021 07:59:27 +0000 Received: by outflank-mailman (input) for mailman id 80388; Tue, 02 Feb 2021 07:59:25 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l6qar-00054u-QJ for xen-devel@lists.xenproject.org; Tue, 02 Feb 2021 07:59:25 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l6qaq-0008Bt-Ug; Tue, 02 Feb 2021 07:59:24 +0000 Received: from 54-240-197-239.amazon.com ([54.240.197.239] helo=a483e7b01a66.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1l6qaq-0005Vl-P8; Tue, 02 Feb 2021 07:59:24 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: MIME-Version:Date:Message-ID:From:References:To:Subject; bh=PMmzMAArqVH1l6YZzvwo1qCQH2Z4azKlIqLB2VxigfA=; b=peXsMGrjbb0hYJLmsGEVnUoqoS vh8onzuImGs9EcpLqmHPitSZYO0f2ZNsKDaO2efvwlbiUajLMGGiolWG7DCgI+sy0vc47RNP+uSlM 5Ir2G4SPu2LCVuE9hhFhsvZPdROcbyJh4Y6Vq3/ED3jhPFL82JGN13+VWdt3+hxvM9YY=; Subject: Re: Null scheduler and vwfi native problem To: Dario Faggioli , =?UTF-8?Q?Anders_T=c3=b6rnqvist?= , xen-devel@lists.xenproject.org, Stefano Stabellini References: <207305e4e2998614767fdcc5ad83ced6de982820.camel@suse.com> <744ddde6-a228-82fc-76b9-401926d7963b@xen.org> <18ef4619-19ae-90d2-459c-9b5282b49176@codiax.se> From: Julien Grall Message-ID: <4760cbac-b006-78bc-b064-3265384f6707@xen.org> Date: Tue, 2 Feb 2021 07:59:23 +0000 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 8bit Hi Dario, On 30/01/2021 17:59, Dario Faggioli wrote: > On Fri, 2021-01-29 at 09:08 +0100, Anders Törnqvist wrote: >> On 1/26/21 11:31 PM, Dario Faggioli wrote: >>> Thanks again for letting us see these logs. >> >> Thanks for the attention to this :-) >> >> Any ideas for how to solve it? >> > So, you're up for testing patches, right? > > How about applying these two, and letting me know what happens? :-D > > They are on top of current staging. I can try to rebase on something > else, if it's easier for you to test. > > Besides being attached, they're also available here: > > https://gitlab.com/xen-project/people/dfaggioli/xen/-/tree/rcu-quiet-fix > > I could not test them properly on ARM, as I don't have an ARM system > handy, so everything is possible really... just let me know. > > It should at least build fine, AFAICT from here: > > https://gitlab.com/xen-project/people/dfaggioli/xen/-/pipelines/249101213 > > Julien, back in: > > https://lore.kernel.org/xen-devel/315740e1-3591-0e11-923a-718e06c36445@arm.com/ > > > you said I should hook in enter_hypervisor_head(), > leave_hypervisor_tail(). Those functions are gone now and looking at > how the code changed, this is where I figured I should put the calls > (see the second patch). But feel free to educate me otherwise. enter_hypervisor_from_guest() and leave_hypervisor_to_guest() are the new functions. I have had a quick look at your place. The RCU call in leave_hypervisor_to_guest() needs to be placed just after the last call to check_for_pcpu_work(). Otherwise, you may be preempted and keep the RCU quiet. The placement in enter_hypervisor_from_guest() doesn't matter too much, although I would consider to call it as a late as possible. Cheers, -- Julien Grall