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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 8575CC46CD2 for ; Wed, 24 Jan 2024 13:15:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=EOJO21mMWm9Ve37XvF5zAOvUvne3pqlm8zmlzW92C/4=; b=T6eMx7fZW8lRw/330GWuTILqKs 7crxmM2LLk2JfMlBM+OT0mrWVcqeGGT9sqNMmEPtxNDe3EHlTNrVW2SbO34IcHLK0ovbMzhOiDAvc dJLM6QvSgpKpEcUI7hxZSpx/PuuC3KBHAI9ItWRQenSCTTa2cCp+zoK1lTKWjK/opC0p0uBSUfa3L 5fgH/fuxjHVnVAAlHa0FmgDU/fkjWDxXk3iiwjNIFnQOLlKHAhXYs2EGxZqFiQjK3XlX+euK1XEz/ TvcFO1Qh/cSXNLwj4l+4ogNKJrJIHms7sDVKeckdNK42dCiTrR2/cUfHhZbdYXA+ivWG3aeOOKMc9 4OtGMIsg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1rSd6S-003Qu7-0N; Wed, 24 Jan 2024 13:15:40 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1rSbwc-0031eL-36 for linux-nvme@lists.infradead.org; Wed, 24 Jan 2024 12:01:28 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1706097684; 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; bh=EOJO21mMWm9Ve37XvF5zAOvUvne3pqlm8zmlzW92C/4=; b=AIRZ+6IqGSTpTHhEX7E10BzgetD84nbIdeaDeP3LcaTEb28an3QkqcKKdY2pn1EtQU5UkE j/gwWisx9prOBv+Zb+M7zfu5V1FLY6Nr2+3No6a9OLx3CroE4INXKtgqavXBLpJOiLQrul FsE8eGXD2wWKF/Yy4skkePUFkcHqE9Y= 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-34-hTHzp1ECNrKOB1WIMu4y9w-1; Wed, 24 Jan 2024 07:00:01 -0500 X-MC-Unique: hTHzp1ECNrKOB1WIMu4y9w-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (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 C43F73C0F1A9; Wed, 24 Jan 2024 12:00:00 +0000 (UTC) Received: from fedora (unknown [10.72.116.11]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4EA262166B32; Wed, 24 Jan 2024 11:59:57 +0000 (UTC) Date: Wed, 24 Jan 2024 19:59:54 +0800 From: Ming Lei To: linux-block@vger.kernel.org, virtualization@lists.linux.dev, linux-nvme@lists.infradead.org Cc: ming.lei@redhat.com Subject: [Report] requests are submitted to hardware in reverse order from nvme/virtio-blk queue_rqs() Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.6 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240124_040127_181880_040ED8AD X-CRM114-Status: UNSURE ( 5.63 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org Hello, Requests are added to plug list in reverse order, and both virtio-blk and nvme retrieves request from plug list in order, so finally requests are submitted to hardware in reverse order via nvme_queue_rqs() or virtio_queue_rqs, see: io_uring submit_bio vdb 6302096 4096 io_uring submit_bio vdb 12235072 4096 io_uring submit_bio vdb 7682280 4096 io_uring submit_bio vdb 11912464 4096 io_uring virtio_queue_rqs vdb 11912464 4096 io_uring virtio_queue_rqs vdb 7682280 4096 io_uring virtio_queue_rqs vdb 12235072 4096 io_uring virtio_queue_rqs vdb 6302096 4096 May this reorder be one problem for virtio-blk and nvme-pci? Thanks, Ming