From nobody Sun Nov 16 05:54:20 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=crudebyte.com ARC-Seal: i=1; a=rsa-sha256; t=1599048700; cv=none; d=zohomail.com; s=zohoarc; b=Ko0VprPkMCcromYl2PCMr17oWz+HS5ooTL3kLR9IwzpJbS6Xs35iz8vvsAoxEKNGdZLfZs2Uu6E3k62IPlW8CUYYwVnbGnfZelQ+GYVqlP6ihEgwCk2OFoYVqkET2WNZunirDUFYC9mriRhxWDv/pDjo0PPoWurEQMAehVLFwjU= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1599048700; h=Cc:Date:From:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:Message-ID:Sender:Subject:To; bh=fSSwOLmtYTd5TDhGKDCGMV9HN1BEsGEhQ5bypOdALM0=; b=mdXErL1UhKxXVLMBSdYw3w/kPdyP9EKC0gSJEwy0EiVYURzd+Qky9X6P9mvAEdW/pSMzAjEQJpWH6zfA2dW3SpN+nsjmpp6eh28DvHxeSMkiTq7UxD2rwdmhPpmypuqg/NTG13pG+RyQ591kOIGJMkQKQiWkUWarRTEzbul48TU= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1599048700523423.12958582538477; Wed, 2 Sep 2020 05:11:40 -0700 (PDT) Received: from localhost ([::1]:59288 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kDRc2-0001GA-K6 for importer@patchew.org; Wed, 02 Sep 2020 08:11:38 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52388) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from <08de36b1ffff4a102834adedb15ff316d93418f2@lizzy.crudebyte.com>) id 1kDRbP-0000Yn-GL for qemu-devel@nongnu.org; Wed, 02 Sep 2020 08:10:59 -0400 Received: from lizzy.crudebyte.com ([91.194.90.13]:35703) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from <08de36b1ffff4a102834adedb15ff316d93418f2@lizzy.crudebyte.com>) id 1kDRbN-0000oM-Jo for qemu-devel@nongnu.org; Wed, 02 Sep 2020 08:10:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Message-Id:Cc:To:Subject:Date:From:Content-Type: Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Content-ID: Content-Description; bh=fSSwOLmtYTd5TDhGKDCGMV9HN1BEsGEhQ5bypOdALM0=; b=ZQfGF oSCdSubJjaYUEFoBtWM460geAMwLOpRb5n7d8ChX+Rd2enWMrzX9ltdMk8Qg2eqL9Dp7i+EimIjox yr8OOYCRWYzY77j+St35ZcoiqE5AFQgUnx1FEr2SyuIaeBdA83c9/BaysPVLl2H2JFJZ7HoiAYsha Ro/dbU3Ttc6hAA1X2k0jfhnKbGx2ORuHw0oT7sfs/4kXmRYRwLjnUFapcC3Evak8cHVPzDlu+AWfi MFMHgqFoyUDpWXGtdXyFbuBl7KOHQZB411R5IDpBIEfmkbXppUPy2XIJlD0XCYEiHob7bclizAqY9 NcmDN602aYTtMMGfCA2JXGrj9q1Tw==; From: Christian Schoenebeck Date: Wed, 2 Sep 2020 13:22:49 +0200 Subject: [PATCH] 9pfs: log warning if msize <= 8192 To: qemu-devel@nongnu.org Cc: Greg Kurz Message-Id: Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: none client-ip=91.194.90.13; envelope-from=08de36b1ffff4a102834adedb15ff316d93418f2@lizzy.crudebyte.com; helo=lizzy.crudebyte.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/02 07:41:09 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_NONE=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+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @crudebyte.com) Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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. 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; } =20 + /* 8192 is the default msize of Linux clients */ + if (s->msize <=3D 8192) { + warn_report_once( + "9p: degraded performance: a reasonable high msize should be " + "chosen on client/guest side (chosen msize is <=3D 8192)." + ); + } + marshal: err =3D pdu_marshal(pdu, offset, "ds", s->msize, &version); if (err < 0) { --=20 2.20.1