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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 38DD2C433FE for ; Thu, 7 Oct 2021 08:36:03 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 0318E610E6 for ; Thu, 7 Oct 2021 08:36:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 0318E610E6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:53548 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mYOsk-0008B1-81 for qemu-devel@archiver.kernel.org; Thu, 07 Oct 2021 04:36:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51706) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mYOpS-0002pP-Gw for qemu-devel@nongnu.org; Thu, 07 Oct 2021 04:32:39 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:37046) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mYOpO-00056T-E7 for qemu-devel@nongnu.org; Thu, 07 Oct 2021 04:32:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1633595553; 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=G5GTR2dM1AkAO+O8oDPs1d5Me5yvxratZjJs0B4zTQ8=; b=NtI27dMyHH3GYoa0LEOK00eP9EQVh10tOfTawPm/9L4jn8IRzjlqYCBmTkeg9lBmd1G8eT RAB3RGOEcIDK1lhVSMWXV7+/5c78XcUF/yv1cddaWaBEdNffCt/uAN9J2uXunGwKCn4Kuh iDDmpfZZNaMpJv3H852EuBlKAOTTJ20= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-586-rx79p6b_PTiCoy0l-U9HcA-1; Thu, 07 Oct 2021 04:32:28 -0400 X-MC-Unique: rx79p6b_PTiCoy0l-U9HcA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4EBDC101796F; Thu, 7 Oct 2021 08:32:27 +0000 (UTC) Received: from localhost (unknown [10.39.194.238]) by smtp.corp.redhat.com (Postfix) with ESMTP id DB11160583; Thu, 7 Oct 2021 08:32:26 +0000 (UTC) Date: Thu, 7 Oct 2021 06:23:59 +0100 From: Stefan Hajnoczi To: Christian Schoenebeck Subject: Re: [PATCH v2 0/3] virtio: increase VIRTQUEUE_MAX_SIZE to 32k Message-ID: References: MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="LLz5XnO6Go+Dl95d" Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -12 X-Spam_score: -1.3 X-Spam_bar: - X-Spam_report: (-1.3 / 5.0 requ) BAYES_00=-1.9, DATE_IN_PAST_03_06=1.592, DKIMWL_WL_HIGH=-0.05, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Laurent Vivier , qemu-block@nongnu.org, "Michael S. Tsirkin" , qemu-devel@nongnu.org, Jason Wang , Amit Shah , David Hildenbrand , Greg Kurz , Raphael Norwitz , virtio-fs@redhat.com, Eric Auger , Hanna Reitz , "Gonglei \(Arei\)" , Gerd Hoffmann , Paolo Bonzini , =?iso-8859-1?Q?Marc-Andr=E9?= Lureau , Fam Zheng , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --LLz5XnO6Go+Dl95d Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Oct 04, 2021 at 09:38:00PM +0200, Christian Schoenebeck wrote: > At the moment the maximum transfer size with virtio is limited to 4M > (1024 * PAGE_SIZE). This series raises this limit to its maximum > theoretical possible transfer size of 128M (32k pages) according to the > virtio specs: >=20 > https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/virtio-v1.1-cs01.html= #x1-240006 Hi Christian, I took a quick look at the code: - The Linux 9p driver restricts descriptor chains to 128 elements (net/9p/trans_virtio.c:VIRTQUEUE_NUM) - The QEMU 9pfs code passes iovecs directly to preadv(2) and will fail with EINVAL when called with more than IOV_MAX iovecs (hw/9pfs/9p.c:v9fs_read()) Unless I misunderstood the code, neither side can take advantage of the new 32k descriptor chain limit? Thanks, Stefan --LLz5XnO6Go+Dl95d Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmFehGkACgkQnKSrs4Gr c8jj7gf9EP8iLDkVsPB3DsimosA2K+3PrRXVRZWUEysCY3blc2e8dVorH4rww8C/ vwch1sIXYASWLhrVEWFpMhKFQZCsh29C+t0q2frOrpnsjejrCJHlf+FLStR+FOiD Db/ayZJHInR7nb6slwIB9gGPPNILC1xFQ/8WbLB6WjHIsG73Ur8vLK4+UT7/ch09 Ujos43uYCTYGpETa896a9cVxqAyo7BLzXng3uunl52Npwr77VQEvqzAoHAKGgZ1f ByC8/QpNHVbyb/r5U85NOHBsmz7/a4xpAKY3Yhl/UO0fXeAeJ90ulxyLVVXxeeBn f9aWXdSM66XYPVv3cMKPfTDpxys6Ag== =RoOJ -----END PGP SIGNATURE----- --LLz5XnO6Go+Dl95d-- From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 7 Oct 2021 06:23:59 +0100 From: Stefan Hajnoczi Message-ID: References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="LLz5XnO6Go+Dl95d" Content-Disposition: inline In-Reply-To: Subject: Re: [Virtio-fs] [PATCH v2 0/3] virtio: increase VIRTQUEUE_MAX_SIZE to 32k List-Id: Development discussions about virtio-fs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Christian Schoenebeck Cc: Kevin Wolf , Laurent Vivier , qemu-block@nongnu.org, "Michael S. Tsirkin" , qemu-devel@nongnu.org, Jason Wang , Amit Shah , David Hildenbrand , Raphael Norwitz , virtio-fs@redhat.com, Eric Auger , Hanna Reitz , "Gonglei (Arei)" , Gerd Hoffmann , Paolo Bonzini , =?iso-8859-1?Q?Marc-Andr=E9?= Lureau , Fam Zheng --LLz5XnO6Go+Dl95d Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Oct 04, 2021 at 09:38:00PM +0200, Christian Schoenebeck wrote: > At the moment the maximum transfer size with virtio is limited to 4M > (1024 * PAGE_SIZE). This series raises this limit to its maximum > theoretical possible transfer size of 128M (32k pages) according to the > virtio specs: >=20 > https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/virtio-v1.1-cs01.html= #x1-240006 Hi Christian, I took a quick look at the code: - The Linux 9p driver restricts descriptor chains to 128 elements (net/9p/trans_virtio.c:VIRTQUEUE_NUM) - The QEMU 9pfs code passes iovecs directly to preadv(2) and will fail with EINVAL when called with more than IOV_MAX iovecs (hw/9pfs/9p.c:v9fs_read()) Unless I misunderstood the code, neither side can take advantage of the new 32k descriptor chain limit? Thanks, Stefan --LLz5XnO6Go+Dl95d Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmFehGkACgkQnKSrs4Gr c8jj7gf9EP8iLDkVsPB3DsimosA2K+3PrRXVRZWUEysCY3blc2e8dVorH4rww8C/ vwch1sIXYASWLhrVEWFpMhKFQZCsh29C+t0q2frOrpnsjejrCJHlf+FLStR+FOiD Db/ayZJHInR7nb6slwIB9gGPPNILC1xFQ/8WbLB6WjHIsG73Ur8vLK4+UT7/ch09 Ujos43uYCTYGpETa896a9cVxqAyo7BLzXng3uunl52Npwr77VQEvqzAoHAKGgZ1f ByC8/QpNHVbyb/r5U85NOHBsmz7/a4xpAKY3Yhl/UO0fXeAeJ90ulxyLVVXxeeBn f9aWXdSM66XYPVv3cMKPfTDpxys6Ag== =RoOJ -----END PGP SIGNATURE----- --LLz5XnO6Go+Dl95d--