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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 B8B71C433E0 for ; Fri, 19 Feb 2021 19:02:32 +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 44D8464EB3 for ; Fri, 19 Feb 2021 19:02:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 44D8464EB3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:56722 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lDB2t-0006nh-8y for qemu-devel@archiver.kernel.org; Fri, 19 Feb 2021 14:02:31 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:38470) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lDB1s-0006J3-Dp for qemu-devel@nongnu.org; Fri, 19 Feb 2021 14:01:28 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:57668) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1lDB1p-0003Eh-HV for qemu-devel@nongnu.org; Fri, 19 Feb 2021 14:01:27 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1613761284; 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=vr08sIKaM5Dhn//7h90nko3kT6pBXSEUeZ9JzYbo8ZY=; b=d5q/gdhHjd6jhPctzXOWTjZckbivymRHHn+0w/1lod1zUgDKNDbcfLzLf4jEaUOGhXXtBB 4jXuZFFUizjzsUihA30QDrQIHJvaXXsre4SRwWB3jXLIakSkUlj2ZqoHm81sep7pSsyDjQ azsp+sRP6SAXU4i14VPN5PHLhRnl9q0= 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-350-v-FzocWLNkyU3boUJcz5sQ-1; Fri, 19 Feb 2021 14:01:20 -0500 X-MC-Unique: v-FzocWLNkyU3boUJcz5sQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B2D6D51D8; Fri, 19 Feb 2021 19:01:18 +0000 (UTC) Received: from horse.redhat.com (ovpn-115-220.rdu2.redhat.com [10.10.115.220]) by smtp.corp.redhat.com (Postfix) with ESMTP id B0D1D60C05; Fri, 19 Feb 2021 19:01:12 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id 2DA8822054F; Fri, 19 Feb 2021 14:01:12 -0500 (EST) Date: Fri, 19 Feb 2021 14:01:12 -0500 From: Vivek Goyal To: Christian Schoenebeck Subject: Re: Can not set high msize with virtio-9p (Was: Re: virtiofs vs 9p performance) Message-ID: <20210219190112.GC3270@redhat.com> References: <20200918213436.GA3520@redhat.com> <17216624.eqST2d0sUl@silver> <20210219160848.GB3270@redhat.com> <2709384.cAWMFGR5kF@silver> MIME-Version: 1.0 In-Reply-To: <2709384.cAWMFGR5kF@silver> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=vgoyal@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=63.128.21.124; envelope-from=vgoyal@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H4=0.001, RCVD_IN_MSPIKE_WL=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: "cdupontd@redhat.com" , "Venegas Munoz, Jose Carlos" , Greg Kurz , qemu-devel@nongnu.org, virtio-fs-list , Stefan Hajnoczi , "Shinde, Archana M" , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Feb 19, 2021 at 06:33:46PM +0100, Christian Schoenebeck wrote: > On Freitag, 19. Februar 2021 17:08:48 CET Vivek Goyal wrote: > > On Fri, Sep 25, 2020 at 10:06:41AM +0200, Christian Schoenebeck wrote: > > > On Freitag, 25. September 2020 00:10:23 CEST Vivek Goyal wrote: > > > > In my testing, with cache=none, virtiofs performed better than 9p in > > > > all the fio jobs I was running. For the case of cache=auto for virtiofs > > > > (with xattr enabled), 9p performed better in certain write workloads. I > > > > have identified root cause of that problem and working on > > > > HANDLE_KILLPRIV_V2 patches to improve WRITE performance of virtiofs > > > > with cache=auto and xattr enabled. > > > > > > Please note, when it comes to performance aspects, you should set a > > > reasonable high value for 'msize' on 9p client side: > > > https://wiki.qemu.org/Documentation/9psetup#msize > > > > Hi Christian, > > > > I am not able to set msize to a higher value. If I try to specify msize > > 16MB, and then read back msize from /proc/mounts, it sees to cap it > > at 512000. Is that intended? > > 9p server side in QEMU does not perform any msize capping. The code in this > case is very simple, it's just what you see in function v9fs_version(): > > https://github.com/qemu/qemu/blob/6de76c5f324904c93e69f9a1e8e4fd0bd6f6b57a/hw/9pfs/9p.c#L1332 > > > $ mount -t 9p -o trans=virtio,version=9p2000.L,cache=none,msize=16777216 > > hostShared /mnt/virtio-9p > > > > $ cat /proc/mounts | grep 9p > > hostShared /mnt/virtio-9p 9p > > rw,sync,dirsync,relatime,access=client,msize=512000,trans=virtio 0 0 > > > > I am using 5.11 kernel. > > Must be something on client (guest kernel) side. I don't see this here with > guest kernel 4.9.0 happening with my setup in a quick test: > > $ cat /etc/mtab | grep 9p > svnRoot / 9p rw,dirsync,relatime,trans=virtio,version=9p2000.L,msize=104857600,cache=mmap 0 0 > $ > > Looks like the root cause of your issue is this: > > struct p9_client *p9_client_create(const char *dev_name, char *options) > { > ... > if (clnt->msize > clnt->trans_mod->maxsize) > clnt->msize = clnt->trans_mod->maxsize; > > https://github.com/torvalds/linux/blob/f40ddce88593482919761f74910f42f4b84c004b/net/9p/client.c#L1045 That was introduced by a patch 2011. commit c9ffb05ca5b5098d6ea468c909dd384d90da7d54 Author: Venkateswararao Jujjuri (JV) Date: Wed Jun 29 18:06:33 2011 -0700 net/9p: Fix the msize calculation. msize represents the maximum PDU size that includes P9_IOHDRSZ. You kernel 4.9 is newer than this. So most likely you have this commit too. I will spend some time later trying to debug this. Vivek