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=-7.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 04205C433E2 for ; Thu, 3 Sep 2020 16:33:53 +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 BC3A020578 for ; Thu, 3 Sep 2020 16:33:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=crudebyte.com header.i=@crudebyte.com header.b="OZ+7VCXJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BC3A020578 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=crudebyte.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:60304 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kDsBL-0004U7-T1 for qemu-devel@archiver.kernel.org; Thu, 03 Sep 2020 12:33:51 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41476) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kDsAW-00037j-QJ for qemu-devel@nongnu.org; Thu, 03 Sep 2020 12:33:00 -0400 Received: from lizzy.crudebyte.com ([91.194.90.13]:44301) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kDsAU-000356-9z for qemu-devel@nongnu.org; Thu, 03 Sep 2020 12:33:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Content-Type:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Content-ID:Content-Description; bh=pILq5udIKjxltpvsYkqscsfykS6P7zuC40+ssEQ1sWY=; b=OZ+7VCXJqa7woaoMW5fY+H2e4u wa17w+EQrsKruOq+gXtDupwyj1iCUKpQvqc60DVCfJzH0U+GETI2BL9OTqoNKU5NpOodwifIAUqxx lNe6jzWrlQYXoLvRQoVBzKugbV6pCWu1Pi7JNi067sxD3dPIgtitslWM3UtJrAWdd/VGmV0SyoKxZ lhf/guC82QRbQzPv4tzEZy0tyC5UWQWz8Cl7PrRQm11s/oHaDYMv83Lc1C97ZbykbQYTAewbljdwC jcNHkQPDtykFhar3OiUvx0D/Pe0+smGPULXPJs/DRSdvsiCgYlvFlN9FcLLFyYNAZPMgXddU/7jvo BqHT+kzQ==; From: Christian Schoenebeck To: qemu-devel@nongnu.org Cc: Greg Kurz , berrange@redhat.com Subject: Re: [PATCH v2 1/1] 9pfs: log warning if msize <= 8192 Date: Thu, 03 Sep 2020 18:32:54 +0200 Message-ID: <2515823.gX3yQePTrF@silver> In-Reply-To: <20200903180248.6199bb7b@bahia.lan> References: <20200903180248.6199bb7b@bahia.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Received-SPF: pass client-ip=91.194.90.13; envelope-from=qemu_oss@crudebyte.com; helo=lizzy.crudebyte.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/03 10:59:11 X-ACL-Warn: Detected OS = Linux 3.11 and newer [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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Donnerstag, 3. September 2020 18:02:48 CEST Greg Kurz wrote: > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > > index 7bb994bbf2..99b6f24fd6 100644 > > --- a/hw/9pfs/9p.c > > +++ b/hw/9pfs/9p.c > > @@ -1353,6 +1353,15 @@ static void coroutine_fn v9fs_version(void *opaque) > > > > goto out; > > > > } > > > > + /* 8192 is the default msize of Linux clients */ > > + if (s->msize <= 8192) { > > I agree that an msize of 8192 suck from a performance standpoint but > I guess many users are msize agnostic, and they use the default value > without even knowing it. They might not even care for performance at > all, otherwise they'd likely ask google and they will eventually land > on: > > https://wiki.qemu.org/Documentation/9psetup#Performance_Considerations > > But with this patch, they will now get a warning each time they start > QEMU, maybe freak out and file reports in launchpad. So I suggest you > turn <= into < to avoid bothering these placid users with a warning. Mmm, that's actually precisely my intended target group: people who have never been aware about the existence of 'msize' before. I keep '<=' for now, I think the log message is already clear that you simply have to make it any 'msize' > 8192 and the warning is gone. > Anyway, it's your choice :) so if you manage to get the #msize anchor to > work as expected: Works now (using raw html anchor instead): https://wiki.qemu.org/Documentation/9psetup#msize > Reviewed-by: Greg Kurz Thanks Greg! > > + warn_report_once( > > + "9p: degraded performance: a reasonable high msize should be > > " > > + "chosen on client/guest side (chosen msize is <= 8192). See " > > + "https://wiki.qemu.org/Documentation/9psetup#msize for > > details." + ); > > + } > > + > > > > marshal: > > err = pdu_marshal(pdu, offset, "ds", s->msize, &version); > > if (err < 0) { Best regards, Christian Schoenebeck