Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:42418 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753324AbeDQNmZ (ORCPT ); Tue, 17 Apr 2018 09:42:25 -0400 Date: Tue, 17 Apr 2018 09:42:24 -0400 From: "J. Bruce Fields" To: Christoph Hellwig Cc: Olga Kornievskaia , linux-nfs@vger.kernel.org Subject: Re: [PATCH v8 0/9] NFSD support for async COPY Message-ID: <20180417134224.GC10291@parsley.fieldses.org> References: <20180413170158.17589-1-kolga@netapp.com> <20180414072202.GA6514@infradead.org> <20180416214522.GC2634@parsley.fieldses.org> <20180417065203.GA15145@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20180417065203.GA15145@infradead.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Mon, Apr 16, 2018 at 11:52:03PM -0700, Christoph Hellwig wrote: > On Mon, Apr 16, 2018 at 05:45:22PM -0400, J. Bruce Fields wrote: > > On Sat, Apr 14, 2018 at 12:22:02AM -0700, Christoph Hellwig wrote: > > > What is the use case for adding all these crazy complications? > > > > Is there anything specific that you think is too complicated? > > It is a lot of complexity for little gain. > > > I know you don't think server-to-server copy offload is worth the > > trouble, but I haven't seen you actually explain why (beyond just that > > it's more complicated). > > I'd like to see numbers for actual, real use cases. Note that this > series doesn't seem to include inter-server support, so this is locally > only, and I'd like to see why we want to support this over the simpler > and better performing CLONE op. Note that we already support COPY (using a read-write loop if necessary). --b.