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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 E1AD2C41604 for ; Tue, 6 Oct 2020 17:14:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B55BE206DD for ; Tue, 6 Oct 2020 17:14:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726100AbgJFROa (ORCPT ); Tue, 6 Oct 2020 13:14:30 -0400 Received: from p3plsmtpa09-06.prod.phx3.secureserver.net ([173.201.193.235]:53816 "EHLO p3plsmtpa09-06.prod.phx3.secureserver.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725769AbgJFRO3 (ORCPT ); Tue, 6 Oct 2020 13:14:29 -0400 X-Greylist: delayed 438 seconds by postgrey-1.27 at vger.kernel.org; Tue, 06 Oct 2020 13:14:29 EDT Received: from [192.168.0.117] ([71.184.94.153]) by :SMTPAUTH: with ESMTPSA id PqQgkZI9Iz5JkPqQgkhcef; Tue, 06 Oct 2020 10:07:11 -0700 X-CMAE-Analysis: v=2.3 cv=aPSOVo1m c=1 sm=1 tr=0 a=vbvdVb1zh1xTTaY8rfQfKQ==:117 a=vbvdVb1zh1xTTaY8rfQfKQ==:17 a=IkcTkHD0fZMA:10 a=mJjC6ScEAAAA:8 a=mRtmDtF74R81MPjdODkA:9 a=QEXdDO2ut3YA:10 a=ijnPKfduoCotzip5AuI1:22 X-SECURESERVER-ACCT: tom@talpey.com Subject: Re: unsharing tcp connections from different NFS mounts To: Bruce Fields , Chuck Lever Cc: Linux NFS Mailing List References: <20201006151335.GB28306@fieldses.org> <43CA4047-F058-4339-AD64-29453AE215D6@oracle.com> <20201006152223.GD28306@fieldses.org> From: Tom Talpey Message-ID: Date: Tue, 6 Oct 2020 13:07:11 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: <20201006152223.GD28306@fieldses.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-CMAE-Envelope: MS4wfPCEQ6bn2vaz27JHv+0OlRx36SR0tGTMknVNIpuVIOZB41UhOMYNFFjkcDl8QVoBWOQtOnoEtxVIIrStlEqX+INRbCV+eKRGKPWMw8FCCeIOMpXMiazE IxvNQkNUOseCw3RUlXSOuoGOhluDFDP9Sbx125zbxpCTthurZBISd54Td6SBIHoDq+xy9+BHEHKLo92tzVgWP4FKtd7zDqUOpD4mbCsalY7XFYNUzixZrUF4 BziFC47QoSYIBSO0l0Z0xQ== Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On 10/6/2020 11:22 AM, Bruce Fields wrote: > On Tue, Oct 06, 2020 at 11:20:41AM -0400, Chuck Lever wrote: >> >> >>> On Oct 6, 2020, at 11:13 AM, bfields@fieldses.org 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 thought this was what the nconnect mount option was for. > > I've suggested that. It doesn't isolate the two mounts from each other > in the same way, but I can imagine it might make it less likely that a > user on one mount will block a user on another? I don't know, it might > depend on the details of their workload and a certain amount of luck. Wouldn't it be better to fully understand the reason for the performance difference, before changing the mount API? If it's a guess, it'll come back to haunt the code for years. For example, maybe it's lock contention in the xprt transport code, or in the socket stack. Just askin'. Tom.