Return-Path: linux-nfs-owner@vger.kernel.org Received: from fieldses.org ([173.255.197.46]:37491 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753922AbbBEQse (ORCPT ); Thu, 5 Feb 2015 11:48:34 -0500 Date: Thu, 5 Feb 2015 11:48:32 -0500 From: "J. Bruce Fields" To: Anna Schumaker Cc: Christoph Hellwig , linux-nfs@vger.kernel.org Subject: Re: [PATCH v2 2/4] NFSD: Add READ_PLUS support for data segments Message-ID: <20150205164832.GB4289@fieldses.org> References: <1422477777-27933-1-git-send-email-Anna.Schumaker@Netapp.com> <1422477777-27933-3-git-send-email-Anna.Schumaker@Netapp.com> <20150205141325.GC4522@infradead.org> <54D394EC.9030902@Netapp.com> <20150205162326.GA18977@infradead.org> <54D39DC2.9060808@Netapp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <54D39DC2.9060808@Netapp.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Thu, Feb 05, 2015 at 11:43:46AM -0500, Anna Schumaker wrote: > On 02/05/2015 11:23 AM, Christoph Hellwig wrote: > > On Thu, Feb 05, 2015 at 11:06:04AM -0500, Anna Schumaker wrote: > >>> If the READ_PLUS implementation can't use the splice read path it's > >>> probably a loss for most workloads. > >>> > >> > >> I'll play around with the splice path, but I don't think it was designed for encoding multiple read segments. > > > > The problem is that the typical case of all data won't use splice > > every with your patches as the 4.2 client will always send a READ_PLUS. > > > > So we'll have to find a way to use it where it helps. While we might be > > able to add some hacks to only use splice for the first segment I guess > > we just need to make the splice support generic enough in the long run. > > > > I should be able to use splice if I detect that we're only returning a single DATA segment easily enough. Oh, good thought, yes maybe that would be enough. But I still wish he had more evidence here. --b.