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=-4.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 68CD7C4363C for ; Wed, 7 Oct 2020 11:27:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EDD3F2076C for ; Wed, 7 Oct 2020 11:27:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="FYSB/qVM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726219AbgJGL1d (ORCPT ); Wed, 7 Oct 2020 07:27:33 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:30224 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726129AbgJGL1d (ORCPT ); Wed, 7 Oct 2020 07:27:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602070052; 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=NDd15FcD4jbZJobjtZjKJ8aW+zrR3z7+6xOSXHLX3/o=; b=FYSB/qVMoyWzs6nVGU+Am+9nsa5ItCrfBD7GNeY6hNrhQJQRCxjfv6bdVnffEroyrX7lUn p2gBIEw9EZuHtPBJpuk5Bqro+VJIudX75S0f3NuQE7H62zSqobXdj2Dkk+wukUHyWaPpQT vQhdnXifhTHRuGNtSa5XBGjdnlFR2HM= 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-397-mpDc0DVdNHqEmB4oYwc3Fg-1; Wed, 07 Oct 2020 07:27:29 -0400 X-MC-Unique: mpDc0DVdNHqEmB4oYwc3Fg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 334DE87950B; Wed, 7 Oct 2020 11:27:28 +0000 (UTC) Received: from [172.16.176.1] (ovpn-64-66.rdu2.redhat.com [10.10.64.66]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B79881002382; Wed, 7 Oct 2020 11:27:27 +0000 (UTC) From: "Benjamin Coddington" To: "J. Bruce Fields" Cc: "Olga Kornievskaia" , linux-nfs Subject: Re: unsharing tcp connections from different NFS mounts Date: Wed, 07 Oct 2020 07:27:26 -0400 Message-ID: <57E3293C-5C49-4A80-957B-E490E6A9B32E@redhat.com> In-Reply-To: <20201007001814.GA5138@fieldses.org> References: <20201006151335.GB28306@fieldses.org> <95542179-0C20-4A1F-A835-77E73AD70DB8@redhat.com> <20201007001814.GA5138@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; format=flowed X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On 6 Oct 2020, at 20:18, J. Bruce Fields wrote: > On Tue, Oct 06, 2020 at 05:46:11PM -0400, Olga Kornievskaia wrote: >> On Tue, Oct 6, 2020 at 3:38 PM Benjamin Coddington >> wrote: >>> >>> On 6 Oct 2020, at 11:13, J. Bruce Fields wrote: >>> >>>> NFSv4.1+ differs from earlier versions in that it always performs >>>> trunking discovery that results in mounts to the same server >>>> sharing a >>>> TCP connection. >>>> >>>> It turns out this results in performance regressions for some >>>> users; >>>> apparently the workload on one mount interferes with performance of >>>> another mount, and they were previously able to work around the >>>> problem >>>> by using different server IP addresses for the different mounts. >>>> >>>> Am I overlooking some hack that would reenable the previous >>>> behavior? >>>> Or would people be averse to an "-o noshareconn" option? >>> >>> I suppose you could just toggle the nfs4_unique_id parameter. This >>> seems to >>> work: >>> >>> flock /sys/module/nfs/parameters/nfs4_unique_id bash -c >>> "OLD_ID=\$(cat >>> /sys/module/nfs/parameters/nfs4_unique_id); echo imalittleteapot > >>> /sys/module/nfs/parameters/nfs4_unique_id; mount -ov4,sec=sys >>> 10.0.1.200:/exports /mnt/fedora2; echo \$OLD_ID > >>> /sys/module/nfs/parameters/nfs4_unique_id" >>> >>> I'm trying to think of a reason why this is a bad idea, and not >>> coming >>> up >>> with any. Can we support users that have already found this >>> solution? >>> >> >> What about reboot recovery? How will each mount recover its own state >> (and present the same identifier it used before). Client only keeps >> track of one? > > Looks like nfs4_init_{non}uniform_client_string() stores it in > cl_owner_id, and I was thinking that meant cl_owner_id would be used > from then on.... > > But actually, I think it may run that again on recovery, yes, so I bet > changing the nfs4_unique_id parameter midway like this could cause > bugs > on recovery. Ah, that's what I thought as well. Thanks for looking closer Olga! I don't see why we couldn't store it for the duration of the mount, and doing so would fix reboot recovery when the uniquifier is changed after a mount. Ben