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=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 09B20C31E5B for ; Wed, 19 Jun 2019 00:06:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D06D720B1F for ; Wed, 19 Jun 2019 00:06:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=permerror (0-bit key) header.d=prgmr.com header.i=@prgmr.com header.b="ZtVBNcPY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725988AbfFSAGV (ORCPT ); Tue, 18 Jun 2019 20:06:21 -0400 Received: from mail.prgmr.com ([71.19.149.6]:52534 "EHLO mail.prgmr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725913AbfFSAGV (ORCPT ); Tue, 18 Jun 2019 20:06:21 -0400 Received: from turtle.mx (96-92-68-116-static.hfc.comcastbusiness.net [96.92.68.116]) (Authenticated sender: adp) by mail.prgmr.com (Postfix) with ESMTPSA id 087F628C002 for ; Wed, 19 Jun 2019 01:03:38 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.prgmr.com 087F628C002 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=prgmr.com; s=default; t=1560920619; bh=Xjj9Zv4HD7Z7rMmQFxYm51gsQ2pNoJOwv55SviarFb0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZtVBNcPYYuzduIo0gbHv8N3qz2ALCVl4ASWGWULneygVZoSbnNOL5UfcDLlwz6z4O UwCY6RDpAkXGoYcf5zL6B7j1Iv27r8wtCd2d0uV9h1z2ovf9p7cEv7CMJy9zV48KIi 3Z4Am1Rwy+6EVIunZC1A39hsEz1i0z2LWSxTvlds= Received: (qmail 22267 invoked by uid 1353); 19 Jun 2019 00:07:46 -0000 Date: Tue, 18 Jun 2019 18:07:46 -0600 From: Alan Post To: Benjamin Coddington Cc: linux-nfs Subject: Re: User process NFS write hang in wait_on_commit with kworker Message-ID: <20190619000746.GT4158@turtle.email> References: <20190618000613.GR4158@turtle.email> <6DE07E49-D450-4BF7-BC61-0973A14CD81B@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6DE07E49-D450-4BF7-BC61-0973A14CD81B@redhat.com> Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Tue, Jun 18, 2019 at 11:29:16AM -0400, Benjamin Coddington wrote: > I think that your transport or NFS server is dropping the response to an > RPC. The NFS client will not retransmit on an established connection. > > What server are you using? Any middle boxes on the network that could be > transparently dropping transmissions (less likely, but I have seen them)? > I've found 8 separate NFS client hangs of the sort I reported here, and in all cases the same NFS server was involved: an Ubuntu Trusty system running 4.4.0. I've been upgrading all of these NFS servers, haven't done this one yet--the complicity of NFS hangs I've been seeing have slowed me down. Of the 8 NFS clients with a hang to this server, about half are in the same computer room where packets only transit rack switches, with the other half also going through a computer room router. I see positive dropped and overrun packet counts on the NFS server interface, along with a similar magnitude of pause counts on the switch port for the NFS server. Given the occurences of this issue only this rack switch and a redundant pair of top-of-rack switches in the rack with the NFS server are in-common between all 8 NFS clients with write hangs. -A -- Alan Post | Xen VPS hosting for the technically adept PO Box 61688 | Sunnyvale, CA 94088-1681 | https://prgmr.com/ email: adp@prgmr.com