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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C25FC4332F for ; Wed, 2 Nov 2022 19:15:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230409AbiKBTPY (ORCPT ); Wed, 2 Nov 2022 15:15:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42064 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230224AbiKBTOq (ORCPT ); Wed, 2 Nov 2022 15:14:46 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1905A10B43 for ; Wed, 2 Nov 2022 12:13:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1667416434; 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=sfmdRZi2oRqTqcnLT5pjPUSkV22lKIz3gi/HpKleL5o=; b=hI4YxzkIqTCkajFp2yWwdZdG7DiEKlhkv65dzGULf0YtvvTgr2BFgRJIDemDJj8fVt3FzF ktCJ98QXsYlnGbgAdsdX6tpufBWL74cNj+mRGQsA0ujl1GhTpJ7nvw+qfgZzgrYfUBm+Gu qecSTF7G9wmW/bR4c5ff5KfHRsnFrjg= 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-262-PxzAMl8kMMG9hH5Z1BqGww-1; Wed, 02 Nov 2022 15:13:51 -0400 X-MC-Unique: PxzAMl8kMMG9hH5Z1BqGww-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 ABA5E87B2A1; Wed, 2 Nov 2022 19:13:50 +0000 (UTC) Received: from localhost (unknown [10.39.192.88]) by smtp.corp.redhat.com (Postfix) with ESMTP id DC2C21121320; Wed, 2 Nov 2022 19:13:49 +0000 (UTC) Date: Wed, 2 Nov 2022 15:13:47 -0400 From: Stefan Hajnoczi To: Jason Wang Cc: Stefan Hajnoczi , Yongji Xie , "Michael S. Tsirkin" , Ming Lei , Ziyang Zhang , io-uring@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel , "Denis V. Lunev" , Xiaoguang Wang Subject: Re: ublk-qcow2: ublk-qcow2 is available Message-ID: References: <1d051d63-ce34-1bb3-2256-4ced4be6d690@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="jPo3x6rSJt98BRBl" Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org --jPo3x6rSJt98BRBl Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Nov 01, 2022 at 10:36:29AM +0800, Jason Wang wrote: > On Tue, Oct 25, 2022 at 8:02 PM Stefan Hajnoczi wrot= e: > > > > On Tue, 25 Oct 2022 at 04:17, Yongji Xie wrot= e: > > > > > > On Fri, Oct 21, 2022 at 2:30 PM Jason Wang wrot= e: > > > > > > > > > > > > =E5=9C=A8 2022/10/21 13:33, Yongji Xie =E5=86=99=E9=81=93: > > > > > On Tue, Oct 18, 2022 at 10:54 PM Stefan Hajnoczi wrote: > > > > >> On Tue, 18 Oct 2022 at 09:17, Yongji Xie wrote: > > > > >>> On Tue, Oct 18, 2022 at 2:59 PM Ming Lei wrote: > > > > >>>> On Mon, Oct 17, 2022 at 07:11:59PM +0800, Yongji Xie wrote: > > > > >>>>> On Fri, Oct 14, 2022 at 8:57 PM Ming Lei wrote: > > > > >>>>>> On Thu, Oct 13, 2022 at 02:48:04PM +0800, Yongji Xie wrote: > > > > >>>>>>> On Wed, Oct 12, 2022 at 10:22 PM Stefan Hajnoczi wrote: > > > > >>>>>>>> On Sat, 8 Oct 2022 at 04:43, Ziyang Zhang wrote: > > > > >>>>>>>>> On 2022/10/5 12:18, Ming Lei wrote: > > > > >>>>>>>>>> On Tue, Oct 04, 2022 at 09:53:32AM -0400, Stefan Hajnocz= i wrote: > > > > >>>>>>>>>>> On Tue, 4 Oct 2022 at 05:44, Ming Lei wrote: > > > > >>>>>>>>>>>> On Mon, Oct 03, 2022 at 03:53:41PM -0400, Stefan Hajno= czi wrote: > > > > >>>>>>>>>>>>> On Fri, Sep 30, 2022 at 05:24:11PM +0800, Ming Lei wr= ote: > > There are ways to minimize that cost: > > 1. The driver only needs to fetch the device's sq index when it has > > run out of sq ring space. > > 2. The device can include sq index updates with completions. This is > > what NVMe does with the CQE SQ Head Pointer field, but the > > disadvantage is that the driver has no way of determining the sq index > > until a completion occurs. >=20 > Probably, but as replied in another thread, based on the numbers > measured from the networking test, I think the current virtio layout > should be sufficient for block I/O but might not fit for cases like > NFV. I remember that the Linux virtio_net driver doesn't rely on vq spinlocks because CPU affinity and the NAPI architecture ensure that everything is CPU-local. There is no need to protect the freelist explicitly because the functions cannot race. Maybe virtio_blk can learn from virtio_net... 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