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.gnu.org (lists.gnu.org [209.51.188.17]) (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 5CB46C7EE23 for ; Tue, 30 May 2023 16:25:09 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1q429M-0001wE-KG; Tue, 30 May 2023 12:24:44 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1q429G-0001rJ-JR for qemu-devel@nongnu.org; Tue, 30 May 2023 12:24:38 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1q429E-00069X-B9 for qemu-devel@nongnu.org; Tue, 30 May 2023 12:24:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1685463875; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=+PO7OF1UJIEyhl34/BsyVvrG83vEPKJb7h1Om/b9M+g=; b=TFYWPr1ShaeaFr3cSXk1OBlbi8QoodYj8eac86v8iRCAe5NxQ6OBHrwWF6iGc2KauDb//h t10qTB7HgEM6MsoXeA2DpV9MuLsAhs2yyce8ZYS3GZNl/FfxCSU9GFwCcuE1ccLmmiZZHr nyat6kOyIoN+5OU4i9pJoxrvsfXRByU= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-83-ahITsgYMPYCTa1zF2WpWBg-1; Tue, 30 May 2023 12:24:33 -0400 X-MC-Unique: ahITsgYMPYCTa1zF2WpWBg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 0662F87282F; Tue, 30 May 2023 16:24:19 +0000 (UTC) Received: from redhat.com (unknown [10.39.194.4]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E24581121330; Tue, 30 May 2023 16:24:14 +0000 (UTC) Date: Tue, 30 May 2023 18:24:13 +0200 From: Kevin Wolf To: Stefan Hajnoczi Cc: qemu-devel@nongnu.org, Coiby Xu , Marcel Apfelbaum , "Michael S. Tsirkin" , "Richard W.M. Jones" , Peter Xu , xen-devel@lists.xenproject.org, Ronnie Sahlberg , Stefano Stabellini , Richard Henderson , Julia Suvorova , Hanna Reitz , Leonardo Bras , eesposit@redhat.com, Fam Zheng , Aarushi Mehta , David Woodhouse , Xie Yongji , Stefano Garzarella , qemu-block@nongnu.org, Eduardo Habkost , Paul Durrant , Stefan Weil , Anthony Perard , Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , Peter Lieven , Paolo Bonzini , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= , Juan Quintela Subject: Re: [PATCH v6 00/20] block: remove aio_disable_external() API Message-ID: References: <20230516190238.8401-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230516190238.8401-1-stefanha@redhat.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.167, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Am 16.05.2023 um 21:02 hat Stefan Hajnoczi geschrieben: > The aio_disable_external() API temporarily suspends file descriptor monitoring > in the event loop. The block layer uses this to prevent new I/O requests being > submitted from the guest and elsewhere between bdrv_drained_begin() and > bdrv_drained_end(). > > While the block layer still needs to prevent new I/O requests in drained > sections, the aio_disable_external() API can be replaced with > .drained_begin/end/poll() callbacks that have been added to BdrvChildClass and > BlockDevOps. > > This newer .bdrained_begin/end/poll() approach is attractive because it works > without specifying a specific AioContext. The block layer is moving towards > multi-queue and that means multiple AioContexts may be processing I/O > simultaneously. > > The aio_disable_external() was always somewhat hacky. It suspends all file > descriptors that were registered with is_external=true, even if they have > nothing to do with the BlockDriverState graph nodes that are being drained. > It's better to solve a block layer problem in the block layer than to have an > odd event loop API solution. > > The approach in this patch series is to implement BlockDevOps > .drained_begin/end() callbacks that temporarily stop file descriptor handlers. > This ensures that new I/O requests are not submitted in drained sections. Thanks, applied to the block branch. Kevin