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 7331EC35274 for ; Mon, 18 Dec 2023 10:29:32 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rFArg-0006CL-ON; Mon, 18 Dec 2023 05:28:48 -0500 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 1rFArd-0006BR-DA for qemu-devel@nongnu.org; Mon, 18 Dec 2023 05:28:45 -0500 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 1rFArb-0006n5-Hf for qemu-devel@nongnu.org; Mon, 18 Dec 2023 05:28:45 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1702895322; 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=PWwpokJxzh/zFMj7WtwruIa5/wWdWQYGt6c8h67H36Q=; b=BQwP1GMJosctPWu0Y7nHKEJH+kMoOSIqVOI/oGAhYOFLubxwKbhf5nD+rsYTX5YGGyEA41 PG4ME5RI4Ye08wgHF6Bj+IOU+fPx/xSatJd+UpObg+kuAjER1hDsKoFIBhJ9VKAHlUN8yY yEg/IRfYOE/lc6q5PTY4bYYkiEEG2LE= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-57-xCh-4qbUNFuCcp8pn7HJTA-1; Mon, 18 Dec 2023 05:28:38 -0500 X-MC-Unique: xCh-4qbUNFuCcp8pn7HJTA-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 375B1280C28A; Mon, 18 Dec 2023 10:28:38 +0000 (UTC) Received: from redhat.com (unknown [10.39.194.189]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 87598492BC6; Mon, 18 Dec 2023 10:28:36 +0000 (UTC) Date: Mon, 18 Dec 2023 11:28:35 +0100 From: Kevin Wolf To: Stefan Hajnoczi Cc: qemu-devel@nongnu.org, Peter Xu , "Michael S. Tsirkin" , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= , David Hildenbrand , Paolo Bonzini , Fam Zheng , qemu-block@nongnu.org Subject: Re: [PATCH v2 0/4] scsi: eliminate AioContext lock Message-ID: References: <20231204164259.1515217-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231204164259.1515217-1-stefanha@redhat.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 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: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.086, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable 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 [ Cc: qemu-block ] Am 04.12.2023 um 17:42 hat Stefan Hajnoczi geschrieben: > v2: > - Reschedule BH in new AioContext if change is detected [Kevin] > - Drop stray "remember" in Patch 2's commit description [Eric] > > The SCSI subsystem uses the AioContext lock to protect internal state. This is > necessary because the main loop and the IOThread can access SCSI state in > parallel. This inter-thread access happens during scsi_device_purge_requests() > and scsi_dma_restart_cb(). > > This patch series modifies the code so SCSI state is only accessed from the > IOThread that is executing requests. Once this has been achieved the AioContext > lock is no longer necessary. > > Note that a few aio_context_acquire()/aio_context_release() calls still remain > after this series. They surround API calls that invoke AIO_WAIT_WHILE() and > therefore still rely on the AioContext lock for now. > > Stefan Hajnoczi (4): > scsi: only access SCSIDevice->requests from one thread > virtio-scsi: don't lock AioContext around > virtio_queue_aio_attach_host_notifier() > scsi: don't lock AioContext in I/O code path > dma-helpers: don't lock AioContext in dma_blk_cb() Thanks, applied to the block branch. Kevin