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 X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CFECAC433DB for ; Mon, 22 Feb 2021 17:13:33 +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 55A4164E21 for ; Mon, 22 Feb 2021 17:13:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 55A4164E21 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kaod.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:40654 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lEEm4-0000EU-B1 for qemu-devel@archiver.kernel.org; Mon, 22 Feb 2021 12:13:32 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:43150) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lEEkg-0006ul-Vg for qemu-devel@nongnu.org; Mon, 22 Feb 2021 12:12:06 -0500 Received: from 5.mo51.mail-out.ovh.net ([188.165.49.213]:56695) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lEEke-0003oJ-UN for qemu-devel@nongnu.org; Mon, 22 Feb 2021 12:12:06 -0500 Received: from mxplan5.mail.ovh.net (unknown [10.108.1.10]) by mo51.mail-out.ovh.net (Postfix) with ESMTPS id 7201B269130; Mon, 22 Feb 2021 18:12:01 +0100 (CET) Received: from kaod.org (37.59.142.95) by DAG8EX1.mxp5.local (172.16.2.71) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Mon, 22 Feb 2021 18:12:00 +0100 Authentication-Results: garm.ovh; auth=pass (GARM-95G001629b4686-cd84-43f6-baca-af62d71ac644, 7322555201F4CCBA135B576978D07BE5564972B5) smtp.auth=groug@kaod.org X-OVh-ClientIp: 78.197.208.248 Date: Mon, 22 Feb 2021 18:11:59 +0100 From: Greg Kurz To: Christian Schoenebeck Subject: Re: Can not set high msize with virtio-9p (Was: Re: virtiofs vs 9p performance) Message-ID: <20210222181159.6b274945@bahia.lan> In-Reply-To: <2848338.ij5OB8EVuP@silver> References: <20200918213436.GA3520@redhat.com> <2337260.PURPEL5hZR@silver> <20210222131814.28e06428@bahia.lan> <2848338.ij5OB8EVuP@silver> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [37.59.142.95] X-ClientProxiedBy: DAG7EX1.mxp5.local (172.16.2.61) To DAG8EX1.mxp5.local (172.16.2.71) X-Ovh-Tracer-GUID: ddeacccc-584c-4aec-b233-701cd0671c0a X-Ovh-Tracer-Id: 16564520904821938479 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgeduledrkeefgdeljecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfqggfjpdevjffgvefmvefgnecuuegrihhlohhuthemucehtddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpeffhffvuffkjghfofggtgfgihesthejredtredtvdenucfhrhhomhepifhrvghgucfmuhhriicuoehgrhhouhhgsehkrghougdrohhrgheqnecuggftrfgrthhtvghrnhepfedutdeijeejveehkeeileetgfelteekteehtedtieefffevhffflefftdefleejnecukfhppedtrddtrddtrddtpdefjedrheelrddugedvrdelheenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhhouggvpehsmhhtphdqohhuthdphhgvlhhopehmgihplhgrnhehrdhmrghilhdrohhvhhdrnhgvthdpihhnvghtpedtrddtrddtrddtpdhmrghilhhfrhhomhepghhrohhugheskhgrohgurdhorhhgpdhrtghpthhtohepvhhgohihrghlsehrvgguhhgrthdrtghomh Received-SPF: pass client-ip=188.165.49.213; envelope-from=groug@kaod.org; helo=5.mo51.mail-out.ovh.net X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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: "Shinde, Archana M" , "Venegas Munoz, Jose Carlos" , qemu-devel@nongnu.org, "Dr. David Alan Gilbert" , virtio-fs-list , Stefan Hajnoczi , "cdupontd@redhat.com" , Vivek Goyal Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, 22 Feb 2021 16:08:04 +0100 Christian Schoenebeck wrote: [...] > I did not ever have a kernel crash when I boot a Linux guest with a 9pfs root > fs and 100 MiB msize. Interesting. > Should we ask virtio or 9p Linux client maintainers if > they can add some info what this is about? > Probably worth to try that first, even if I'm not sure anyone has a answer for that since all the people who worked on virtio-9p at the time have somehow deserted the project. > > > As the kernel code sais trans_mod->maxsize, maybe its something in virtio > > > on qemu side that does an automatic step back for some reason. I don't > > > see something in the 9pfs virtio transport driver > > > (hw/9pfs/virtio-9p-device.c on QEMU side) that would do this, so I would > > > also need to dig deeper. > > > > > > Do you have some RAM limitation in your setup somewhere? > > > > > > For comparison, this is how I started the VM: > > > > > > ~/git/qemu/build/qemu-system-x86_64 \ > > > -machine pc,accel=kvm,usb=off,dump-guest-core=off -m 2048 \ > > > -smp 4,sockets=4,cores=1,threads=1 -rtc base=utc \ > > > -boot strict=on -kernel /home/bee/vm/stretch/boot/vmlinuz-4.9.0-13-amd64 \ > > > -initrd /home/bee/vm/stretch/boot/initrd.img-4.9.0-13-amd64 \ > > > -append 'root=svnRoot rw rootfstype=9p > > > rootflags=trans=virtio,version=9p2000.L,msize=104857600,cache=mmap > > > console=ttyS0' \ > > First obvious difference I see between your setup and mine is that > > you're mounting the 9pfs as root from the kernel command line. For > > some reason, maybe this has an impact on the check in p9_client_create() ? > > > > Can you reproduce with a scenario like Vivek's one ? > > Yep, confirmed. If I boot a guest from an image file first and then try to > manually mount a 9pfs share after guest booted, then I get indeed that msize > capping of just 512 kiB as well. That's far too small. :/ > Maybe worth digging : - why no capping happens in your scenario ? - is capping really needed ? Cheers, -- Greg > Best regards, > Christian Schoenebeck > >