Return-Path: Received: from bombadil.infradead.org ([198.137.202.9]:50210 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964825AbbCXRtX (ORCPT ); Tue, 24 Mar 2015 13:49:23 -0400 Date: Tue, 24 Mar 2015 10:49:16 -0700 From: Christoph Hellwig To: Anna Schumaker Cc: "J. Bruce Fields" , Christoph Hellwig , Marc Eshel , "linux-nfs@vger.kernel.org" , linux-nfs-owner@vger.kernel.org, xfs@oss.sgi.com Subject: Re: [PATCH v3 3/3] NFSD: Add support for encoding multiple segments Message-ID: <20150324174916.GA28906@infradead.org> References: <20150318205554.GA10716@fieldses.org> <5509E824.6070006@Netapp.com> <20150318211144.GB10716@fieldses.org> <20150319153627.GA20852@fieldses.org> <20150320151718.GD2036@fieldses.org> <20150320162303.GA18786@infradead.org> <20150320182621.GH2036@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-nfs-owner@vger.kernel.org List-ID: On Tue, Mar 24, 2015 at 08:43:31AM -0400, Anna Schumaker wrote: > > I don't know, and don't have profiles. I'll either try to reproduce or > > wait till Anna's back from vacation. > > I'm using whatever functions NFSD already uses for reading files, > which I expect go through the VFS. Is there a flag that controls > cache behavior? There's the O_DIRECT flag, but that's not what I mean. If you just wrote to it it's a cached read, if you did unmount the filesystem after writing, or did an echo to /proc/sys/vm/drop_caches you get uncached read behavior.