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=-11.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 1D64CC433E2 for ; Wed, 2 Sep 2020 12:26:33 +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 C708320829 for ; Wed, 2 Sep 2020 12:26:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="dem60d81" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C708320829 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]:44424 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kDRqR-0007jz-V6 for qemu-devel@archiver.kernel.org; Wed, 02 Sep 2020 08:26:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56430) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kDRpu-0007H5-DJ for qemu-devel@nongnu.org; Wed, 02 Sep 2020 08:25:58 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:21320 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kDRps-00033r-Hp for qemu-devel@nongnu.org; Wed, 02 Sep 2020 08:25:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1599049555; h=from:from:reply-to: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=cZ56duPwHcmKh/FS4V4XfTijjn9YZgh6c+U+7cpk1r4=; b=dem60d81RXXM4RfywwFj70swEICG6+rw979WN8nhdcMdbtsbVnQHflL1KzkpbPI17A9KJg m8x2dw1NFBXpsgSHvo94Z578K4aMrDOGtnXLIC3svUJbhzwQMzbfY5F2JsOZ+nijmdCDRt yiUhvOJf2ncE2Nakjdfctmv9DeYC0RE= 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-96-fgcl3rJjPjCohBfDA4riOQ-1; Wed, 02 Sep 2020 08:25:52 -0400 X-MC-Unique: fgcl3rJjPjCohBfDA4riOQ-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 CABF310ABDB7; Wed, 2 Sep 2020 12:25:50 +0000 (UTC) Received: from redhat.com (ovpn-114-158.ams2.redhat.com [10.36.114.158]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EB8D37C5BA; Wed, 2 Sep 2020 12:25:49 +0000 (UTC) Date: Wed, 2 Sep 2020 13:25:47 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Christian Schoenebeck Subject: Re: [PATCH] 9pfs: log warning if msize <= 8192 Message-ID: <20200902122547.GH403297@redhat.com> References: MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.120; envelope-from=berrange@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/02 02:26:30 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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_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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: qemu-devel@nongnu.org, Greg Kurz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Sep 02, 2020 at 01:22:49PM +0200, Christian Schoenebeck wrote: > It is essential to choose a reasonable high value for 'msize' to avoid > severe degraded file I/O performance. This parameter has to be chosen > on client/guest side, and a Linux client defaults to an 'msize' of only > 8192 if the user did not explicitly specify a value for 'msize'. > > Unfortunately many users are not aware that they should specify an > appropriate value for 'msize' to avoid severe performance issues, so > log a performance warning on host side in that case to make it more > clear. What is a more reasonable "msize" value to pick instead of 8k ? ie at what msize is I/O not several degraded ? If there a reason that Linux can't pick a better default ? > > Signed-off-by: Christian Schoenebeck > --- > hw/9pfs/9p.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > index 7bb994bbf2..33e948d636 100644 > --- a/hw/9pfs/9p.c > +++ b/hw/9pfs/9p.c > @@ -1353,6 +1353,14 @@ static void coroutine_fn v9fs_version(void *opaque) > goto out; > } > > + /* 8192 is the default msize of Linux clients */ > + if (s->msize <= 8192) { > + warn_report_once( > + "9p: degraded performance: a reasonable high msize should be " > + "chosen on client/guest side (chosen msize is <= 8192)." > + ); > + } > + > marshal: > err = pdu_marshal(pdu, offset, "ds", s->msize, &version); > if (err < 0) { > -- > 2.20.1 > > Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|