From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754733AbcKNQ7z (ORCPT ); Mon, 14 Nov 2016 11:59:55 -0500 Received: from casper.infradead.org ([85.118.1.10]:57270 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932705AbcKNQ7y (ORCPT ); Mon, 14 Nov 2016 11:59:54 -0500 Date: Mon, 14 Nov 2016 16:59:48 +0000 (GMT) From: James Simmons To: Greg Kroah-Hartman cc: devel@driverdev.osuosl.org, Andreas Dilger , Oleg Drokin , Gregoire Pichon , Linux Kernel Mailing List , Lustre Development List Subject: Re: [PATCH v4] staging: lustre: mdc: manage number of modify RPCs in flight In-Reply-To: <20161114151737.GA18183@kroah.com> Message-ID: References: <1478793073-21814-1-git-send-email-jsimmons@infradead.org> <20161114151737.GA18183@kroah.com> User-Agent: Alpine 2.20 (LFD 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20161114_165948_183274_7C7ABE93 X-CRM114-Status: GOOD ( 17.38 ) X-Spam-Score: -1.9 (-) X-Spam-Report: SpamAssassin version 3.4.1 on casper.infradead.org summary: Content analysis details: (-1.9 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 NO_RELAYS Informational: message was not relayed via SMTP -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Thu, Nov 10, 2016 at 10:51:13AM -0500, James Simmons wrote: > > From: Gregoire Pichon > > > > This patch is the main client part of a new feature that supports > > multiple modify metadata RPCs in parallel. Its goal is to improve > > metadata operations performance of a single client, while maintening > > the consistency of MDT reply reconstruction and MDT recovery > > mechanisms. > > > > It allows to manage the number of modify RPCs in flight within > > the client obd structure and to assign a virtual index (the tag) to > > each modify RPC to help server side cleaning of reply data. > > > > The mdc component uses this feature to send multiple modify RPCs > > in parallel. > > Is this a new feature? Why should we take this now and not just wait > until the code is out of staging? Yes on the server side. So the problem on our meta data servers couldn't handle writing mulitiple bits of data to the back end disk at ths same time. One client side the issue was the metadata operations were being serialized by a mutex in the MDC layer. That is what this patch fixed. So for the client it would be a performance improvement patch.