Return-Path: Received: from mexforward.lss.emc.com ([128.222.32.20]:29712 "EHLO mexforward.lss.emc.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750854Ab1FJFg5 convert rfc822-to-8bit (ORCPT ); Fri, 10 Jun 2011 01:36:57 -0400 From: To: , CC: , , Date: Fri, 10 Jun 2011 01:36:05 -0400 Subject: RE: [PATCH 87/88] Add configurable prefetch size for layoutget Message-ID: References: <09142112ff0115f7f22124a69ead7b9bb5e0958f.1307464382.git.rees@umich.edu> <4DEED80A.4000102@panasas.com> <20110608021852.GA20998@merit.edu> <4DF062D6.7010304@panasas.com> <20110609114929.GA28157@merit.edu> <4DF0CB5D.60000@panasas.com> <20110609135846.GA32565@merit.edu> <4DF139D0.1080200@tonian.com> In-Reply-To: <4DF139D0.1080200@tonian.com> Content-Type: text/plain; charset="us-ascii" Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 Hi, Benny, -----Original Message----- From: linux-nfs-owner@vger.kernel.org [mailto:linux-nfs-owner@vger.kernel.org] On Behalf Of Benny Halevy Sent: Friday, June 10, 2011 5:23 AM To: Jim Rees Cc: Peng Tao; linux-nfs@vger.kernel.org; peter honeyman Subject: Re: [PATCH 87/88] Add configurable prefetch size for layoutget On 2011-06-09 06:58, Jim Rees wrote: > Benny Halevy wrote: > > > My understanding is that layoutget specifies a min and max, and the server > > There's a min. What do you consider the max? > Whatever gets into csa_fore_chan_attrs.ca_maxresponsesize? > > The spec doesn't say max, it says "desired." I guess I assumed the server > wouldn't normally return more than desired. No, the server may freely upgrade the returned layout segment by returning a layout for a larger byte range or even returning a RW layout where a READ layout was asked for. [PT] It is true that server can upgrade the layout segment freely. But there is always a price to pay. Server has to be dealing with all kind of clients. If server returns more than being asked for, it may hurt other clients.